Technicaltraining. Productinformation. G12Chassisand

Technicaltraining.Productinformation.

BMWService

G12ChassisandSuspension

qxf0291

ST1501

Generalinformation

Symbolsused

Thefollowingsymbolisusedinthisdocumenttofacilitatebettercomprehensionortodrawattentiontoveryimportantinformation:

Containsimportantsafetyinformationandinformationthatneedstobeobservedstrictlyinordertoguaranteethesmoothoperationofthesystem.

Informationstatusandnational-marketversions

BMWGroupvehiclesmeettherequirementsofthehighestsafetyandqualitystandards.Changesinrequirementsforenvironmentalprotection,customerbenefitsanddesignrendernecessarycontinuousdevelopmentofsystemsandcomponents.Consequently,theremaybediscrepanciesbetweenthecontentsofthisdocumentandthevehiclesavailableinthetrainingcourse.

Thisdocumentbasicallyrelatestolefthanddrivevehicles.Furtherdifferencesmayariseastheresultoftheequipmentspecificationinspecificmarketsorcountries.

Additionalsourcesofinformation

Furtherinformationontheindividualtopicscanbefoundinthefollowing:

• Owner'sHandbook• IntegratedServiceTechnicalApplication.

Contact:[email protected]

©2015BMWAG,Munich

ReprintsofthispublicationoritspartsrequirethewrittenapprovalofBMWAG,Munich

TheinformationcontainedinthisdocumentformsanintegralpartofthetechnicaltrainingoftheBMWGroupandisintendedforthetrainerandparticipantsintheseminar.RefertothelatestrelevantinformationsystemsoftheBMWGroupforanychanges/additionstothetechnicaldata.

Contact:SebastianRiedelTel.:+49(0)8938265044E-mail:[email protected]

Informationstatus:June2015BV-72/TechnicalTraining

mailto:[email protected]

G12ChassisandSuspensionContents1. Introduction.............................................................................................................................................................................................................................................1

1.1. Developmentcode...............................................................................................................................................................................................11.2. Chassisandsuspensioncomparison....................................................................................................................................11.3. Overviewofchassisandsuspension.....................................................................................................................................2

1.3.1. Highlights..........................................................................................................................................................................................3

2. Axles.....................................................................................................................................................................................................................................................................52.1. Frontaxle............................................................................................................................................................................................................................5

2.1.1. Versionsofthefrontaxlesupport..............................................................................................................82.1.2. NotesforService..................................................................................................................................................................8

2.2. Rearaxle...........................................................................................................................................................................................................................112.2.1. NotesforService.............................................................................................................................................................12

3. AirSuspension.............................................................................................................................................................................................................................163.1. Airsupplysystem.............................................................................................................................................................................................19

3.1.1. Technicaldata........................................................................................................................................................................233.1.2. Solenoidvalveblock...................................................................................................................................................24

3.2. Airsuspensionstrut......................................................................................................................................................................................253.3. Rideheightsensor..........................................................................................................................................................................................273.4. Operatingstrategy...........................................................................................................................................................................................29

3.4.1. High level.......................................................................................................................................................................................333.4.2. Normal level..............................................................................................................................................................................343.4.3. Sport level....................................................................................................................................................................................35

3.5. NotesforService...............................................................................................................................................................................................363.5.1. Liftingthevehicle............................................................................................................................................................363.5.2. Transportmode...................................................................................................................................................................373.5.3. Bleedingtheairsuspension...........................................................................................................................373.5.4. Fillingtheairsuspension....................................................................................................................................37

3.6. Systemwiringdiagram.............................................................................................................................................................................38

4. Brakes............................................................................................................................................................................................................................................................404.1. Servicebrakes........................................................................................................................................................................................................42

4.1.1. Brakedesign............................................................................................................................................................................424.1.2. Pedalmechanismmounting...........................................................................................................................43

4.2. Parkingbrake............................................................................................................................................................................................................444.2.1. Functions.......................................................................................................................................................................................474.2.2. Braketeststand.................................................................................................................................................................48

4.3. Serviceinformation.........................................................................................................................................................................................494.3.1. Servicebrakes.......................................................................................................................................................................494.3.2. Parkingbrake..........................................................................................................................................................................50

G12ChassisandSuspensionContents5. Wheels/Tires.................................................................................................................................................................................................................................51

5.1. Puncturedetectionsystems............................................................................................................................................................525.2. TirePressureMonitorRDCi.............................................................................................................................................................52

5.2.1. Wheelelectronics............................................................................................................................................................54

6. DrivingStabilityControl.............................................................................................................................................................................................566.1. DynamicStabilityControl(DSC)...............................................................................................................................................59

6.1.1. Hydrauliccircuitdiagram.....................................................................................................................................616.1.2. Functions.......................................................................................................................................................................................626.1.3. Systemwiringdiagram............................................................................................................................................64

6.2. Steering.............................................................................................................................................................................................................................666.2.1. Steeringwheel.....................................................................................................................................................................676.2.2. Steeringcolumnadjustment.........................................................................................................................686.2.3. Versionoverview................................................................................................................................................................696.2.4. IntegralActiveSteering..........................................................................................................................................716.2.5. Serviceinformation.......................................................................................................................................................786.2.6. Systemwiringdiagram............................................................................................................................................80

6.3. ElectronicDamperControl(EDC)...........................................................................................................................................856.3.1. Shockabsorberdesign..........................................................................................................................................856.3.2. Systemoverview...............................................................................................................................................................876.3.3. Electricalshockabsorbercontrol...........................................................................................................89

6.4. Anti-rollbar..................................................................................................................................................................................................................926.5. Standardsuspension...................................................................................................................................................................................94

6.5.1. Chassisandsuspensionsetup..................................................................................................................946.6. ActiveComfortDrive....................................................................................................................................................................................95

6.6.1. Predictivecontrol.............................................................................................................................................................986.6.2. Electricactiverollstabilization(EARSV).................................................................................1026.6.3. Controlstrategy..............................................................................................................................................................1096.6.4. Systemwiringdiagramofelectricactiverollstabilization

EARSV...........................................................................................................................................................................................112

G12ChassisandSuspension1.Introduction

1

1.1.DevelopmentcodeThenewBMW7SeriesG12willbelaunchedonthemarketfromOctober2015.

Intermsofthechassisandsuspension,thenewBMW7Seriesoffersincreasedcomfortwithoutanycompromisesindrivingdynamics.

1.2.ChassisandsuspensioncomparisonComponent F01/F02 G12Frontaxle Double-wishbonefrontaxle Double-wishbonefrontaxleFrontsuspension Steelsprings AirsuspensionFrontdamping ElectronicDamperControl

(EDC)ElectronicDamperControl(EDC)

Anti-rollbar,front Conventionalorhydraulicactivestabilizer(ARS)

Conventionalorelectricalactivestabilizer(EARSV)

Rearaxle Five-linkrearsuspension Five-linkrearsuspensionRearsuspension Steelspringsorrearair

suspension(optionalequipmentintheF01)

Airsuspension2axle

Reardamping ElectronicDamperControl(EDC)

ElectronicDamperControl(EDC)

Rearanti-rollbar ConventionalorhydraulicactivestabilizerARS

ConventionalorelectricalactivestabilizerEARSV

Frontbrake Brakediscsuptodia.348mm Brakediscsuptodia.395mmRearbrakes Brakediscsuptodia.345mm Brakediscsuptodia.370mmParkingbrake Drumbrakeswith

electromechanicalparkingbrakeEMF

Discbrakeswithcombinedbrakecaliperfortheelectricparkingbrake

Wheels/tires Run-flattires(RSC) NormaltiresTirePressureMonitor(RDC) RDC RDCiSteering ElectronicPowerSteeringor

IntegralActiveSteeringElectronicPowerSteeringorIntegralActiveSteering


2

1.3.Overviewofchassisandsuspension

OverviewofchassisandsuspensionintheG12

Index Explanation1 Airsuspensionstrut,frontaxle2 12Vbattery(forEARSV)3 Brakeservo4 Steeringcolumnadjustment5 Steeringwheel6 Airsuspensionstrut,rearaxle7 Five-linkrearaxle(HA5)8 Rearaxleslipanglecontrol(HSR)(optionalequipment)9 ElectricactiverollstabilizationrearEARSV(optionalequipment)10 Pressureaccumulator2liters11 Airsupplysystemoftwo-axleridelevelcontrol12 Pressureaccumulator4liters13 Discbrakewithintegratedparkingbrakefortherearaxle


3

Index Explanation14 DynamicStabilityControl(DSC)15 Discbrakeforfrontaxle16 Double-wishbonefrontaxle17 ElectricactiverollstabilizationfrontEARSV(optionalequipment)18 ElectronicPowerSteering(electromechanicalpowersteering)(EPS)

ThefollowingtableshowsacomparisonofthechassisandsuspensionontheG12.

G12Rear-wheeldrive Four-wheeldrive

Wheelbase 3210mm 3210mm

Turningcircle* 12.8m 12,9m

Groundclearance 135mm 135mmMaximumvehicleheight 1505mm 1505mmMinimumvehicleheight 1475mm 1475mmVehicleheightatnormallevel 1485mm 1485mmVehicleheightathighlevel 1505mm 1505mmVehicleheightatsportlevel 1475mm 1475mm

*Theturningcirclevaluesrefertovehicleswithbasicsteering.

1.3.1.HighlightsThefollowingtableshowsthedifferentequipmentspecificationsintheareaofthechassisandsuspensionfortheG12.

Systems Basicchassisandsuspension

IntegralActiveSteering

ActiveComfortDrive

ElectronicPowerSteering(EPS) XEPSwithvariablerackgeometry XRearaxleslipanglecontrol(HSR) XTwo-axleridelevelcontrol XElectronicDamperControl(EDC) XFrontaxleanti-rollbar XRearaxleanti-rollbar XElectricactiverollstabilizationfront(EARSV)

X

Electricactiverollstabilizationrear(EARSV)

X


4

Systems Basicchassisandsuspension

IntegralActiveSteering

ActiveComfortDrive

Wheelaccelerationsensors

X

StereoKAFAScamera XAuxiliarybattery(12 V) X

Thefollowingoptionalequipmentisavailableinadditiontothebasicchassisandsuspension:

• IntegralActiveSteering• ActiveComfortDrive

Bothequipmentoptionscanbecombinedwitheachotherandareavailableforalldrivevariants(alsoxDrive).Itwaspossibletoreducethecarbondioxideemissionsandincreasethecontroldynamicsthroughcompleteelectrificationofthetwooptionalequipmentsystems.Inthecustomer'sperception,thisisexpressedinalowerfuelconsumptionwithincreasedcomfortaswellasasportierdrivingfeeling.

Thedrivercaninfluencethecontrolcharacteristicsofthedifferentsuspensioncontrolsystemsbymeansofthedrivingexperienceswitch.FurtherinformationonthisisprovidedintheTechnicalTrainingManual“G12DriverAssistanceSystems”.

G12ChassisandSuspension2.Axles

5

2.1.FrontaxleThedouble-wishbonefrontaxleoffersoptimumalignmentofthecamberofthefrontwheelsinrelationtotheroadwayineverydrivingsituation.Duringthecompressionandreboundmovements,awheelthereforealwayshasexactlythecambervaluethatguaranteesoptimumtransferofcorneringforcesinrelationtotheroadway.Thisensuresexcellenttirecontactwiththeroadandthetireisabletotransferhighlateralforces.Theattainablehighlateralaccelerationforcesarethuspossiblewithouttheotherwisenecessaryfirmchassisandsuspensionsetup.

Withthedouble-wishbonefrontaxle,theshockabsorberdoesnotperformanywheelcontroltasks.Thismeansthattheshockabsorberarepracticallyfreeoflateralforcesandcanreactsensitivelytoroadbumps.

Sincethedouble-wishbonefrontaxlehasasmallkinematicleverarm,disturbancevariablessuchasroadjointsorpotholesgenerateonlyasmalltorqueaboutthesteeringaxis.

Thesumofalladvantagesmeansthatthedouble-wishbonefrontaxlemakesitpossibletoresolvetheconflictofgoalsbetweencomfortandsportiness.


6

OverviewoffrontaxleonG12withxDrive

Index Explanation1 Supportbearingonairsuspensionstrut2 ActuatorforElectronicDamperControl(EDC)3 Wishbone,bottom4 Steeringbox5 Crossmember6 Universaljointofsteeringshafttosteeringgear7 Castsidesection8 Strut


7

Index Explanation9 Serviceopening10 Rearstiffeningplate11 Steeringshaft12 Universaljointofsteeringshafttosteeringcolumn13 Trianglewishbone,top14 Sidemember15 Swivelbearing16 Wheelbearingunit17 Trackrodhead18 Trailinglink19 Transversetube20 Frontserviceflap21 Lever22 Castcorner23 Castcornerconnection24 Springstrutholder

Inordertoachievethelowestpossiblevehicleweight,thefrontaxlecomponentsaremadealmostcompletelyfromaluminium.

Thedesignofthedouble-wishbonefrontaxleoffersthefollowingadvantages:

• Highagilityduetoabsorptionofhighlateralaccelerationforces.• Outstandingrollstabilizationwhencorneringwithoutanyreductioninridecomfort.• Comfortable,goodspringresponseoftheaxleandgooddirectionalstability.• Highcomfortduetominimuminfluenceofdisturbancevariables.

Inadditiontoensuringdrivingdynamicsandridecomfort,thedouble-wishbonefrontaxlealsoperformsvariouscrashfunctions.Thefrontaxlesupportispartofthecrashstructureofthebodyandformsanadditionalloadpath.Thisensuresthattheincreasedrequirementsrelatingtopedestrianprotectionaremet.

Drivingwithoutastiffeningplateisnotpermittedduetotheresultantlackofvehiclestability.


8

2.1.1.VersionsofthefrontaxlesupportTwodifferentfrontaxlesupportsareuseddependingonthevehicleequipment.

VersionsofthefrontaxlesupportintheG12

Index ExplanationA Rear-wheeldrivesDriveB All-wheeldrivexDrive

2.1.2.NotesforServiceTwodifferentwishbonesareavailabletoServiceforcambercorrection.

CambercorrectionbyupperwishboneintheG12


9

Index ExplanationA Cambercorrectionbyupperwishbone+30minB Cambercorrectionbyupperwishbone-30min

Inordertoavoiddamagetotheballbearingontheupperwishbone,itmustbeensuredwhenperformingdisassemblyorassemblyworkthatthedeflectionangleoftheballjointdoesnotexceedavalueof55°.

Thefollowingtableshowswhenwheelalignmentisnecessaryonthefrontaxlewhenacomponentisreplaced.

Replacementofacomponentonthefrontaxle

Wheelalignmentrequired

Frontaxlesupport YESSteeringbox YESWishbone,bottom YESRubbermountforwishbone,bottom YESTrailinglink NORubbermountfortrailinglink NOTrianglewishbone,top NORubbermountforupperwishbone NOTrackrod YESSwivelbearing YESWheelbearing NOAirsuspensionstrut NOSupportbearing NO

Thefollowingtableshowswhenwheelalignmentisnecessaryonthefrontaxlewhenacomponentisundone.

Undoingthescrewconnectionatthefrontaxle


Frontaxlesupporttobody NOSteeringboxtofrontaxlesupport YESBottomwishbonetofrontaxlesupport YESBottomwishbonetoswivelbearing NOTrailinglinktofrontaxlesupport NOTrailinglinktoswivelbearing NOUpperwishbonetobody NO


10

Undoingthescrewconnectionatthefrontaxle


Upperwishbonetoswivelbearing NOTrackrodtosteeringbox NOTrackrodendtotrackrod YESTrackrodendtoswivelbearing NOSpringstruttobottomwishbone NOSupportbearingtobody NOBottomsteeringshafttosteeringbox NOUppersteeringshafttosteeringcolumn NO


11

2.2.Rearaxle

OverviewofrearaxleintheG12

Index Explanation1 Supportbearing2 Airsuspensionstrut3 Frontrubbermount4 Rearrubbermount5 Airdeflector


12

Index Explanation6 Cambercontrolarm7 Wishbone8 Camberlink9 Wheelbearingunit10 Wheelcarrier11 Trailingarm12 Controlarm13 Compressionstrut14 Axlesupport

Thefive-linkrearaxleoftheG12ischaracterizedbyprecisewheelguidance,whichcomesintoitsowninvariousdrivingsituations,suchasduringloadreversalsorthetransitionfromcorneringtostraight-aheaddriving.Inaddition,thefive-linkrearaxleoffersveryhighcomfortincombinationwithsportydrivingdynamics.

Itwaspossibletoresolvethisconflictofgoalsbymeansofthefollowingmeasures:

• Doubleflexiblerear-axlerubbermounts• Highstructuralrigidityoftherearaxlesupport• Largesupportareaoftherearaxlesupport

Itwaspossibletokeeptheunsprungmassesofthefive-linkrearaxlelowthroughtheuseofanaluminiumwheelcarrieraswellasvariousforgedaluminiumandsheetsteelcontrolarms.

Cleverdefinitionofthekinematicpointsaswellasprecisedesignoftheballjointsandrubbermountsresultinalargespringtravelrangeincombinationwithoptimumwheelguidance.Thesmallactingleverarmsensureparticularlygoodinsensitivitytobumpsintheroad.Theextremelyrigidcontrolarmsaswellasthetorsion-freerearaxlesupportandbodyconnectionsrealizedbymeansofcompressionstrutsresultinextremelyprecisewheelguidance.

Theairdeflectorsunderthecontrolarmsminimiseswirlandthusincreasetheefficiencyofthevehicle.

2.2.1.NotesforServiceThefollowingtableshowswhenwheelalignmentisnecessaryontherearaxlewhenacomponentisreplaced.

Replacementofacomponentontherearaxle


Rearaxlesupport YESRubbermountforrearaxlesupport YESCambercontrolarm YESCamberlink YESTrailingarm YES


13

Replacementofacomponentontherearaxle


Wishbone YESBalljointinthewheelcarrier YESControlarm YESWheelcarrier YESWheelbearing NOAirsuspensionstrut NOSupportbearing NO

Thefollowingtableshowswhenwheelalignmentisnecessaryontherearaxlewhenacomponentisundone.

Undoingacomponentontherearaxle WheelalignmentrequiredRearaxlesupporttobody YESFrontcompressionstruttobody NOCamberlinktorearaxlesupport YESCambercontrolarmtowheelcarrier YESCamberlinktorearaxlesupport YESCamberlinktowheelcarrier NOTrailingarmtorearaxlesupport YESTrailingarmtowheelcarrier YESControlarmtorearsuspensionsubframe YESControlarmtohubcarrier NOWishbonetorearaxlesupport NOWishbonetowheelcarrier NOAirsuspensionstruttowheelcarrier NOSupportbearingtobody NO


14

Rearaxlepositioning

ComparisonofrearaxleontheF01/F02withtheG12

Index ExplanationA RearaxleoftheF01/F02B RearaxleoftheG121 Body2 Centeringmountingforrearaxlesupport3 Mountingforrearaxlesupport4 Rearaxlesupport5 Rubbermountoftherearaxlesupport

OntheG12,nocenteringmountingsareusedonthebodyforalignmentoftherearaxle.Thismakesitpossibletoensureduringassemblythattherubbermountsoftherearaxlearescrewedtothebodycompletelywithoutanytension.Bumpsintheroadareisolatedandarenottransmittedtothebodyduetodirectcontactoftherubbermounts.

Newspecialtoolsareusedforremovalandassemblyoftherearaxlesupport.Therearaxlesupportisheldinthecorrectpositionforinstallationbymeansof2guidepins.Forthedetailedprocedure,refertothecurrentrepairinstructions.


15

CenteringtoolforremovingandinstallingtherearaxleintheG12

Index Explanation1 Centeringpinforlongitudinalandtransversedirections(x-andyaxes)2 Centeringpinforlongitudinaldirection(y-axis)

Basicalignmentoftherearaxlesupportisensuringbythecentringpinforlongitudinalandtransversedirections.Duetothepermittedproductiontolerancesoftherearaxlesupport,thesupportispositionedonlyinlongitudinaldirectionbythesecondcentringpin.

Anincorrectprocedureforpositioningtherearaxlesupportcanleadtoproblemsduringwheelalignment.

G12ChassisandSuspension3.AirSuspension

16

Inordertoguaranteeuniformridecomfortindependentlyoftheloadstatus,theG12isequippedasstandardwithairsuspensiononthefrontandrearaxles.Thetwo-axleridelevelcontroloftheG12isofferedonlyincombinationwithelectricallycontrolledshockabsorbers.

Theairsuspensionincreasestheridecomfort.Thesystemperformsadjustmentmainlyatstandstill,e.g.inordertocompensateforachangeinheightduetothevehicleload.Theinertiaofthesystemmeansthatitcannotreacttodrivingdynamicsdisturbancevariables,whichmayoccurwhenthevehicleisdrivenquicklyontwistingroads.Dynamiccontrolwhendrivingservesonlytocompensateforchangesinheightduetoafallingfueltankvolumeaswellastemperaturechangesoftheairintheairsuspensionstruts.

Theairsuspensionoffersthefollowingadvantages:

• Increaseindrivingsafety,sincetheself-levellingsuspensionautomaticallykeepstheheightofthevehiclebodyatapredefinednominalride-levelinallloadstates.

• Highridecomfortduetoautomaticadaptationoftheoscillationbehaviortothevehicleweight.• Increasedcustomerbenefitthroughmanualleveladjustmentbymeansoftherideheight

selectionswitch.


17

Systemoverviewoftwo-axleridelevelcontrolintheG12

Index ExplanationA Compressedairline,frontright(colorcodeblack)B Compressedairline,rearright(colorcodeblue)C Compressedairline,rearleft(colorcodered)D Compressedairline,frontleft(colorcodegreen)E Compressedairlineforpressureaccumulator(colorcodeyellow)1 Airsuspensionstrut,frontright2 EDCvalve,frontright(ElectronicDamperControl)3 Rideheightsensor,frontright4 Rearrightpowerdistributionbox5 Relayforairsupplysystem


18

Index Explanation6 VerticalDynamicsPlatform(VDP)(centralcontrolunit)7 Airsuspensionstrut,rearright8 Positivebatteryterminaldistributor9 Airsuspensionstrut,rearleft10 Pressureaccumulator2liter11 Pressureaccumulator4liter12 Airsupplysystem13 Rideheightselectionswitch14 Airsuspensionstrut,frontleft

ThecentralcontrolunitforcontrollingtheairsuspensionistheVerticalDynamicsPlatform(VDP).TheVerticalDynamicsPlatform(VDP)controlunitreadsinthecurrentrideheightvaluesbymeansofthe4rideheightsensors.TheVerticalDynamicsPlatform(VDP)activatesthesolenoidvalvesofthesolenoidvalveblockinordertoperformcontrolactions.

Controlactionsatstandstillandatlowvehiclespeeds(0–20km/h/0–12mph)areachievedbyusingthestoragevolumeofthetwopressureaccumulators.Forcontrolactionswhendriving(>20km/h/>12mph),therequiredcompressedairisnottakenfromthepressureaccumulator,butisgeneratedbythecompressorandforwardeddirectlytothecorrespondingairsuspensionstruts.Inexceptionalsituations,thecompressorcanalsobeswitchedonwhenthevehicleisatstandstill.

Theincreaseinvolumeintheairsuspensionstrutliftsthevehiclebody.Achievementofthenominalride-levelheightisdetectedbythe4rideheightsensorsandactivationofthecorrespondingsolenoidvalvesisinterrupted.Three-pointcontrolisusedforprocessinginordertoavoidfrequentre-adjustment.Therearaxleiscontrolledindividuallybymeansofbothrideheightsensors.Inthecaseofthefrontaxle,thecorrespondingrideheightisadjustedonthebasisofameanvalue.

Thecompressedairlineshavedifferentcolorsinordertoavoidconfusionduringservicingworkonthesolenoidvalveblock.Thefollowingtablecontainsanoverviewofthecolorcodes.

Colorcode ComponentYellow PressureaccumulatorBlack Airsuspensionstrut,frontrightGreen Airsuspensionstrut,frontleftBlue Airsuspensionstrut,rearrightRed Airsuspensionstrut,rearleft


19

3.1.AirsupplysystemTheairsupplysystemismadeupofthefollowingcomponents:

• Electricalcompressor• Solenoidvalveblock• Holderwithvibrationdamper

Theairsupplysystemhasthetaskofgeneratingtherequiredcompressedairandcoordinatingtheairflowsbetweentheelectricalcompressor,pressureaccumulatorsandthe4airsuspensionstrutscorrespondingtotherequirements.ThecalculationsrequiredforthisareperformedbytheVerticalDynamicsPlatform(VDP).

Forpackagereasons,thesystemcomprisestwoseparatepressureaccumulatorswithatotalvolumeof6litersandamaximumstoragepressureof17.5bar.Atotalvolumeof105litersisavailabletothesystematmaximumpressure.

AirsupplysystemoftheG12


20

Index Explanation1 Pressureaccumulator2liters2 Airintakehose3 Electricalcompressor4 Holderwithvibrationdamper5 Solenoidvalveblock6 Pressureaccumulator4liters7 Compressedairlineforpressureaccumulator2liters8 Compressedairlineforpressureaccumulator4liters9 Compressedairlineforairsupplytosolenoidvalveblock10 Ventilationtoatmosphere11 Connectionforairintakehose12 Housingcoverforaircleaner61 Plug-incontactforelectricalaircompressor62 Plug-incontactforelectricaldrainsolenoidvalve63 Plug-incontactforsolenoidvalveblock64 Plug-incontactoftemperaturesensor

Theelectricalcompressorisswitchedviaarelay.TherelayisactivatedbytheVerticalDynamicsPlatform(VDP).Inordertopreventvibrationsfrombeingtransmittedintothevehicleinteriorwhenthecompressorisrunning,theairsupplysystemissecuredtothevehiclebodybymeansofaholderwithvibrationdampers.

Topreventthedriverfrombeingirritatedbythestart-upnoisesofthecompressor,thisisswitchedonalmostexclusivelywhiledriving.Thecompressorcanalsobeswitchedonatvehiclestandstillifthefollowingpreconditionsareallmet:

• VehicleconditionResiding/Awake• Sufficientvehiclevoltage• Rideheight–40mmoftheinitializesvalue• Insufficientpressureinthepressureaccumulatorforcontrol

Theintakeairiscleanedbytheaircleanerupstreamofthecompressoranddriedbytheairdrierdownstreamofthecompressor.Cleaningisnecessarysothatthevalvesareprotectedagainstsoiling.Thewaterisextractedfromtheairinordertoprotectthevalvesagainsticingatlowambienttemperatures.Ifthevalvesweretofreezeduetoexcessivelyhighairhumidityintheairsupplysystem,thiswouldmeanthatlevelcontrolbytheairsuspensionwouldnolongerbepossible.Toavoidthis,theairdrierispermanentlycleanedordried.

Thegranulateintheairdrierabsorbsmoistureathighpressureandgivesthisoffagainatlowpressure.Themoistureisextractedfromtheairwhenairflowsthroughthegranulatewhenfillingthesystem.Whenthevehicleheightislowered,theexcessairwithlowpressureisroutedthroughtheairdrier.Thestoredmoistureisthengiveofftotheairagainasitflowspast.Thispermanentregenerationoftheairdrierensuresfault-freeoperationofthesystemwithouttheneedformaintenancework.


21

Pneumaticconnectionsincompressedairsystemsareusuallyprovidedwithstandardisednumbers.Thisservesthepurposeofdifferentiationandisintendedtoexcludethepossibilityoftheconnectionsbeingmixedup.Thefollowingtableprovidesanoverviewofthestandardizednumbercodes.

Numbercode Meaning0 Intakeairconnection1 Energysupply2 Energyoutlet3 Atmosphere


22

Thefollowinggraphicshowsaschematicillustrationoftheairsupplysystem.

SchematicillustrationoftheairsupplysystemintheG12

Index ExplanationA AircompressorB SolenoidvalveblockC FillingD Draining


23

Index Explanation1 Airfilter2 Electricmotor2.1 Energyoutlet,output1(airsuspensionstrut,frontleft)2.2 Energyoutlet,output2(airsuspensionstrut,frontright)2.3 Energyoutlet,output3(airsuspensionstrut,rearleft)2.4 Energyoutlet,output4(airsuspensionstrut,rearright)2.5.1 Energyoutlet,pressureaccumulator12.5.2 Energyoutlet,pressureaccumulator23 Pneumaticdischargevalvewithpressurerelieffunction4 Airdrier5 Non-returnvalve6 Electricaldrainsolenoidvalve7 Temperaturesensor8 Electricalsolenoidvalveofpressureaccumulators9 Electricalsolenoidvalveforrearleftairsuspensionstrut10 Electricalsolenoidvalveforrearrightairsuspensionstrut11 Electricalsolenoidvalveforfrontrightairsuspensionstrut12 Electricalsolenoidvalveforfrontleftairsuspensionstrut13 Pressuresensor

3.1.1.Technicaldata

Compressor Drainsolenoidvalve

Temperaturesensor

Solenoidvalveblock

Supplyvoltage

12V 12V 5 V 12V

Pickupcurrentpervalve

— 0.82A6 — 0.8-1.0A

Holdingcurrentpervalve

— 0.55A6 — 0.55A6

Maximumstartingcurrent

110A6 — — —


24

Compressor Drainsolenoidvalve

Temperaturesensor

Solenoidvalveblock

Maximumcontinuouscurrent

35A6 2.5A6 — 3.1A6

Dynamicpressurecontrol

22.5 bar — — —

Resistance — 9Ω 5kΩat25°C/77°F

6.8kΩ

3.1.2.Solenoidvalveblock

SolenoidvalveblockoftheairsupplyintheG12

Index Explanation2.1 Energyoutlet,output1(airsuspensionstrut,frontleft)2.2 Energyoutlet,output2(airsuspensionstrut,frontright)2.3 Energyoutlet,output3(airsuspensionstrut,rearleft)2.4 Energyoutlet,output4(airsuspensionstrut,rearright)2.5.1 Energyoutlet,pressureaccumulator2l2.5.2 Energyoutlet,pressureaccumulator4l63.1 Activationofsolenoidvalveforfrontleftairsuspensionstrut63.2 Activationofsolenoidvalveofpressureaccumulators63.3 Activationofsolenoidvalveforrearleftairsuspensionstrut63.4 Activationofsolenoidvalveforfrontrightairsuspensionstrut63.5 Ground


25

Index Explanation63.6 Ground63.7 Sensorground(pressuresensor)63.8 Activationofsolenoidvalveforrearrightairsuspensionstrut63.9 Sensorvoltagesupply(pressuresensor)63.10 Sensorsignaloutput(pressuresensor)

Thedifferentelectricalsolenoidvalvesarelocatedinthesolenoidvalveblock.Theseareusedtoforwardthecompressedairtothedifferentcomponentsoftheairsuspension.TherequiredcalculationsforcontroloftheelectricalsolenoidvalvestakeplaceintheVerticalDynamicsPlatform(VDP)controlunit.

Thefollowingcontrolspeedscanbeachievedforaxle-basedchangesintherideheightbythesystem:

• Controlviathepressureaccumulators~10mm/s• Controlviatheelectricalcompressor~2mm/s

Anadvantageoftheinstallationpositionofthepressuresensoristhatthefillingpressuresofthepressureaccumulatorsandairsuspensionstrutscanbereadinwithonlyonesensordependingonactivation.

Whentheelectricalsolenoidvalveofthepressureaccumulatorsisactivated,apressuresensorsuppliesinformationaboutthecurrentfillingpressureofthesystemtotheVerticalDynamicsPlatform(VDP)controlunit.Ifthestoredpressureisnotsufficientforapendingchangeinrideheight,theVerticalDynamicsPlatform(VDP)controlunitswitchesonthecompressorforpressurebuild-up.However,thecompressorisswitchedononlysubjecttocertainpreconditionswhenthevehicleisatstandstillsothatcomfortisnotimpaired(seeAirsupplysystem).

Intheeventofactivationofthesolenoidvalvesforoperationoftheairsuspensionstruts,thepressuresensorsuppliesthefillingpressuresofthecorrespondingairsuspensionstruts.

3.2.AirsuspensionstrutTheheightofthevehiclebodyisautomaticallycontrolledviathepressureintheairsuspensionstrutinallloadstates.Thispreventsthevehiclebodyfromsinkingwhenthevehicleisloaded.Theairsupplyfortheairsuspensionstrutsisprovidedbyanelectricallydrivencompressorand2airaccumulators.Theairsuspensionthusfunctionsindependentlyoftheoperatingconditionofthecombustionengineandcanalsocompensateunevenloading(e.g.slopingload)byindividualwheelcontrolontherearaxle.


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AirsuspensionstrutsonfrontandrearaxlesintheG12

Index ExplanationA Airsuspensionstrutonthefrontaxle(illustrationfromall-wheeldrive)B Airsuspensionstrutonrearaxle1 Pot,upperpart2 Pot,lowerpart3 Gaiter4 Dustboot5 ControlvalveoftheElectronicDamperControl(EDC)6 Dampertube7 Electricalconnectionfordamperadjustment8 Pneumaticconnectionwithintegratedresidualpressureholdingvalve

Ontheairsuspensionstrut,thecoilspringisreplacedbyaU-typebellows.Theairispressedintotheairsuspensionstrutviaacompressedairconnection.TheU-typebellowsoftheairsuspensionstrutunrollsasaresultofthepressureincreaseandraisesthevehiclebody.Whentheairsuspensionstrutisvented,thepressurefallsandtheU-typebellowsrollsupagainsothatthevehiclebodyislowered.


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Thereisaresidualpressureholdingvalveinsidethepneumaticconnectionstopreventcompletepressurereductionintheairsuspensionstrut.Aresidualpressureof1.8–2.7barisheldwhenthecompressedairlinesareremoved.

Thepneumaticconnectionswithintegratedresidualholdingvalveontheairsuspensionstrutcannotbereplacedseparately.Theairsuspensionstrutwillbedamagedifitisattemptedtoremovedthepneumaticconnectionswithintegratedresidualpressureholdingvalve.

Airsuspensionstrut,frontaxle

Airsuspensionstrut,rearaxle

Airvolumeinnormalposition 2.87L 2.85LCompressiontravel 65mm 86mmReboundtravel 76mm 106.4mmFillingpressureondelivery 1.8-2.7bar 1.8-2.7bar

3.3.Rideheightsensor

RideheightsensorintheG12


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Index Explanation1 Holder2 Articulatedrodwithballsocket3 Deflectionlever4 Rideheightsensor

TheVerticalDynamicsPlatform(VDP)controlunitreadsinthecurrentrideheightvaluesofthevehiclebodybymeansofthe4rideheightsensors.Themaximummeasuringrangeoftherideheightsensoris70°.Theoutputisananaloguevoltagesignalbetween0.5Vand4.5V.

Therideheightsensorhasthefollowingelectricalconnections:

• Voltagesupply(5V)• Groundconnection• Signaloutput(0.5–4.5V)

RideheightsignaloftherideheightsensorsintheG12

Index ExplanationV VoltageinVW Angle

Afterrenewalofoneormorerideheightsensors,theservicefunctionforrideheightadjustmentmustbeperformedusingtheBMWdiagnosissystemISTA.

TherideheightvaluesarestoredintheBodyDomainController.Theyarealsousedforleveladjustmentoftheheadlights.


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3.4.Operatingstrategy

InputandoutputdiagramoftheairsuspensionintheG12

Index Explanation1 VerticalDynamicsPlatform(VDP)2 Compressor3 Solenoidvalveblock4 Drivingexperienceswitch5 Doorcontactswitch6 Rideheightselectionswitch7 Temperaturesensor(insidethecompressor)


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Index Explanation8 Pressuresensor(insidethesolenoidvalveblock)9 Rideheightsensor10 Vehicleelectricalsystemvoltage11 Vehiclespeed

ConfigurationoptionsoftheairsuspensionintheG12

Index ExplanationA NormallevelorSportlevelactivatedB Highlevelactivated1 SPORTbuttononthedrivingexperienceswitch2 Rideheightselectionswitch

Therideheightcanbeadjustedmanuallybymeansoftherideheightselectionswitchandthedrivingexperienceswitch.Threedifferentrideheightsareavailable.


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RideheightsoftheG12

Index ExplanationA Sportlevel(-10mm)B Normallevel(+/-0mm)C Highlevel(+20mm)

Situation Highlevel Normallevel SportlevelRideheight +20mm +/–0mm -10mmRideheightactivation

Rideheightselectionswitch

— 1)Drivingexperienceswitch2)Drivingspeed> ~ 140km/h/> ~ 87mph

Speed 0–40km/h/0–25mph

0~140km/h/0~87mph

1)0km/h–finalspeed2)~140km/h/~ 87mph–finalspeed

Thefollowingprerequisitesmustbemetinordertoperformmanualadjustmentintherideheightbymeansoftherideheightselectionswitch:

• DrivingreadinessResiding/Awakeordrivingbetween0–40km/h/0–25mph• Sufficientvehiclevoltage• Doorsclosed• Pressureaccumulatorwithsufficientfillingpressure

(onlyrelevantfordrivingreadinessResiding/Awake)


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ThefollowinggraphicshowstheoperatingstrategyoftheairsuspensionintheG12.

OperatingstrategyoftheairsuspensionintheG12

Index ExplanationA Highlevel(+20mm)B Normallevel(+/-0mm)C Sportlevel(-10mm)H Rideheightofthevehiclebodyv Vehiclespeed1 RideheightselectionswitchsettoHighlevel2 DrivingexperienceswitchinComfortposition3 DrivingexperienceswitchinSportposition


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3.4.1.Highlevel

OperatingstrategyoftheairsuspensionintheG12atHighlevel

Index ExplanationA Highlevel(+20mm)B Normallevel(+/-0mm)C Sportlevel(-10mm)H Rideheightofthevehiclebodyv Vehiclespeed1 RideheightselectionswitchsettoHighlevel2 DrivingexperienceswitchinComfortposition3 DrivingexperienceswitchinSportposition

Inthespeedrangebetween0–40km/h/0–25mph,theHighlevel(+20mm)canbeactivatedmanuallyviatherideheightselectionswitch.Thisrideheightsettingisintendedtoallowthedrivertodriveovershouldersorrampswithalargegradientanglewithoutdamagingthevehicleduetotheincreasedgroundclearance.Thefollowingrideheightsaresetautomaticallyifthisspeedrangeisexceeded.

1 IfthedrivingexperienceswitchisinComfortposition,therideheightisloweredtoNormallevel(+/-0mm).

2 IfthedrivingexperienceswitchisinSportposition,therideheightisloweredtoSportlevel(-10mm).


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Whenadrivingspeedof~140km/h/~87mphisexceeded,thevehiclebodyisautomaticallyloweredfromNormalleveltoSportlevel(-10mm)independentlyoftherespectiveswitchsettings.LoweringtoSportleveloffersthefollowingadvantages:

• Lowvehiclecenterofgravityandthusincreaseddrivingdynamics.• Improvedaerodynamicsandthuslowerfuelconsumption.

3.4.2.Normallevel

OperatingstrategyoftheairsuspensionintheG12atNormallevel

Index ExplanationA Highlevel(+20mm)B Normallevel(+/-0mm)C Sportlevel(-10mm)H Rideheightofthevehiclebodyv Vehiclespeed1 RideheightselectionswitchatNormallevel2 DrivingexperienceswitchinComfortsetting

Normallevel(+/-0mm)canbesetbymeansofthefollowingswitchpositions.

• RideheightselectionswitchinNormalposition.• DrivingexperienceswitchnotinSportposition.


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Whenadrivingspeedof~140km/h/~87mphisexceeded,thevehiclebodyisautomaticallyloweredfromNormalleveltoSportlevel(-10mm)independentlyoftherespectiveswitchsettings.LoweringtoSportleveloffersthefollowingadvantages:

• Lowvehiclecenterofgravityandthusincreaseddrivingdynamics.• Improvedaerodynamicsandthuslowerfuelconsumption.

3.4.3.Sportlevel

OperatingstrategyoftheairsuspensionintheG12atSportlevel

Index ExplanationA Highlevel(+20mm)B Normallevel(+/-0mm)C Sportlevel(-10mm)H Rideheightofthevehiclebodyv Vehiclespeed1 RideheightselectionswitchatNormallevel2 DrivingexperienceswitchinSportsetting

Sportlevel(-10mm)canbesetbymeansofthefollowingswitchpositions.

• RideheightselectionswitchinNormalposition.• DrivingexperienceswitchinSportposition.


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Sportlevel(-10mm)offersthehighestdrivingdynamicsofallrideheightsduetothelowvehiclecenterofgravity.Thefuelconsumptionalsofallsduetotheimprovedaerodynamics.

3.5.NotesforServiceComplete(100%)tightnessoftheairsuspensioncannotbeguaranteedduetothenumerousflexiblecompressedairlineswiththecorrespondingcompressedairconnections.Adefinedlowlossofcompressedairisthereforepermissible.IfthevehicleisparkedatNormallevel,therideheightmaybeloweredbyuptoamaximumof–2mmafter24hours.Thismeansthattherideheightmaybeloweredbyupto-60mmforavehiclethathasbeenparkedfor30dayswithouttherebeingafaultcausedbyaleak.

SideviewoftheG12withairsuspensionloweredtomaximumextent

Sincecomponentsdonotallleaktothesameextentfortolerancereasons,itisalsopossiblethatthevehiclewillbeslopingatanangleafteraprolongedstandstilltime.

LowandslopingvehiclepositionsareautomaticallycompensatedbytheairsuspensionafterdetectionofthevehicleconditionResiding/Awake.Forthispurpose,themissingcompressedairisforwardedtothecorrespondingspringstrutsbythepressureaccumulator.Ifthefillingpressureofthepressureaccumulatorsistoolow,thelackofairiscompensatedbyswitchingontheelectricalcompressor.

Thefollowingscenariosforactivationoftheelectricalcompressorarepossible:

1 Iftherideheightislessthan–40mm,thecompressorwillbeswitchedononlywhentheengineisrunning.

2 Iftherideheightismorethan–40mmandthevehicleelectricalsystemhassufficientvoltage,thecompressorwillalreadybeswitchedonwhenthevehicleconditionResiding/Awakeisdetected.

3.5.1.LiftingthevehicleTheairsuspensionhasajackdetectionfunction.Thispreventscontrolactionoftheairsuspensionwhenthevehicleislifted.


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3.5.2.TransportmodeTheairsuspensionisintransportmodewhennewvehiclesaredelivered.Achangeintherideheightisnotpossible.TransportmodemustbedeletedusingtheBMWdiagnosissystemISTAduringthepre-deliverycheck.Thedifferentrideheightsoftheairsuspensioncanbeselectedonlyaftersuccessfulstart-upoftheairsuspension(transportmodedeleted).

3.5.3.BleedingtheairsuspensionWhenworkingoncomponentsoftheairsuspensionsystem,itisnecessarytodepressurizethesystembeforeundoingthevariouscompressedairlines.ThiscanbedoneusingtheBMWdiagnosissystemISTAbymeansofableedingroutine.Here,thevarioussolenoidvalvesoftheairsuspensionstrutsandtheelectricaldrainsolenoidvalveareactivatedsimultaneously.Inordertoprotectthevalvesagainstoverheating,thebleedingroutinecannotbeperformedanarbitrarynumberoftimesinsuccession.However,thefunctionisavailableagainafteradefinedwaitingperiod.

Inordertoavoiddamagetotheairsuspensionstruts,thevehicleshouldberaisedslightlyusingavehiclehoistduringthebleedingroutine.

However,itisnotrecommendedtocompletelyliftthevehicleduringthebleedingroutineasthishamperscompleteemptyingofthecompressedairfromtheairsuspensionstruts.

3.5.4.FillingtheairsuspensionThesystemisfilledautomaticallyviathevehicle'selectricalcompressorassoonasthemarginalconditionsforthisaremet.InordertoperformaleakagetestoftheairsuspensioninService,theelectricalcompressorcanbeswitchedonmanuallytofillthesystemusingtheBMWdiagnosissystemISTA.Iftheairsuspensionisfilledseveraltimes,theelectricalcompressormaybeswitchedofftopreventthecompressorfrombeingdamaged.


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3.6.Systemwiringdiagram

Systemwiringdiagramofthetwo-axleridelevelcontrolintheG12


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Index Explanation1 Rideheightsensor,frontleft2 EDCvalve,frontleft(ElectronicDamperControl)3 EDCvalve,frontright(ElectronicDamperControl)4 DSCrideheightsensor,frontright5 Powerdistributionbox,frontright6 BodyDomainController(BDC)7 Rearrightpowerdistributionbox8 VerticalDynamicsPlatform(VDP)9 Rideheightsensor,rearright10 EDCvalve,rearright(ElectronicDamperControl)11 Relayforairsupplysystem12 Positivebatteryterminaldistributor13 Compressor14 Solenoidvalveblock15 Airsupplysystem16 EDCvalve,rearleft(ElectronicDamperControl)17 Ride-heightsensor,rearleft18 CrashSafetyModule(ACSM)19 Rideheightselectionswitch20 DynamicStabilityControl(DSC)

G12ChassisandSuspension4.Brakes

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ThefollowinggraphicprovidesanoverviewofthebrakesystemoftheG12.

OverviewofbrakesystemintheG12

Index Explanation1 Plug-incontact,wheel-speedsensor,frontright2 EMFactuator(electromechanicalparkingbrake)3 Plug-incontact,wheelspeedsensor,rearright4 Plug-incontact,brakepadwearsensor,rearright5 Plug-incontact,wheelspeedsensor,rearleft6 Brakedisc,rearaxle7 Brakecaliper,rearaxle8 Auto-Holdbutton9 Parkingbrakebutton10 DSCbutton11 Bearingsupport,pedalmechanism12 Brakeservo13 Brakefluidexpansiontank14 DynamicStabilityControl(DSC)


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Index Explanation15 Brakecaliper,frontaxle16 Brakedisc,frontaxle17 Plug-incontact,wheel-speedsensor,frontleft18 Plug-incontact,brakepadwearsensor,frontleft


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4.1.Servicebrakes

4.1.1.BrakedesignInordertoenhancethevisualappearanceofthebrakes,Blackpaintedcalipersareoptionalinthe“AutobahanPackage”(ZAN).

Versions Frontaxle RearaxleStandardcaliper

AutobahnPackagewithBMWlogoprint

MSport


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4.1.2.Pedalmechanismmounting

MountingofthepedalmechanismonthebrakeservolinkageintheG12

Index ExplanationA BrakeservolinkageB Pedalmechanism1 Ballhead2 Plasticclip

AmodifiedmountingisusedintheG12betweenthepedalmechanismandthebrakeservolinkage.Here,theballheadofthebrakeservolinkageisengagedinaplasticcliponthepedalmechanism.

Anewspecialtoolisneededtoreleasethisconnection.

Partnumber83302409646

Specialtoolforremovingthepedalmechanism


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Whenremovingthepedalmechanism,alwaysobservetheinstructionsinthecurrentrepairinstructions.

4.2.ParkingbrakeTheBMWE65/E66(BMW7Seriesfrom2001–2008)wasthefirstproductionvehicleintheworldwithanelectromechanicalparkingbrakeEMF.ThiswasfollowedbymanyotherBMWmodelswithdifferentelectricalparkingbrakesystems.

Thefollowingadvantagesresultfromtheuseofsuchasystem:

• MorestoragespaceduetoomissionofaparkingbrakeleverandparkingbrakeBowdencable.• Contactpressureofbrakepadscorrectlyadjustedatalltimes.• Variousadditionalfunctionstoassistthedriver(e.g.automaticreleasewhendrivingoff).• Higherbrakingpowerofauxiliarybrakesystem.

Thefollowing2differentelectricalsystemsarecurrentlyusedatBMW:

• Electromechanicalparkingbrake=Cablepullsystemviaduo-servoparkingbrake(Küstersystem).

• Electricparkingbrake=Combinedbrakecaliper(TRW/Continentalsystem).


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Thefollowinggraphicshowsacomparisonofthetwosystems.

SystemcomparisonoftheelectromechanicalparkingbrakeintheF01/F02withtheelectricparkingbrakeoftheG12

Index ExplanationA F01/F02(BMW7Seriesfrom2008–2015)B G12(BMW7Seriesfrom2015)1a DSCcontrolunit(DynamicStabilityControl)1b DSCcontrolunitwithintegratedparkingbrakefunction

(DynamicStabilityControl)2 Instrumentpanel(KOMBI)3 Parkingbrakebutton4 Electricparkingbrakeviaactuatoratcombinedbrakecaliper


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Index Explanation5 Electromechanicalparkingbrakeviaduo-servoparkingbrake6 Electromechanicalparkingbrakeactuatorunitwithintegrated

controlunit(electromechanicalparkingbrake)BDC BodyDomainControllerZGM Centralgatewaymodule

IncontrasttothecablepullsystemintheF01/F02,theelectricparkingbrakesystemwithacombinedbrakecaliperfamiliarfromthesmallerseriesisusedintheG12.

Previously,theparkingbrakewasrealizedbymeansofaduo-servoparkingbrakeintheheavyupperclassvehicles.Theadvantageofthissystemisthehighself-lockingforceofthebrakepadswhentheparkingbrakeisapplied.

Duetotheincreaseinthepreloadforcesofthecombinedbrakecaliperwithelectricparkingbrake,itwaspossibletodispensewiththepreviouslyusedcablepullsystemintheG12.OmissionoftheassociatedcomponentsisbeneficialforweightreductionandalsofortherepairfriendlinessoftheG12.

TheelectricparkingbrakeoftheG12isdifferentiatedaboveallbythefactthatthereisnoseparatecontrolunit.TheelectricparkingbrakeisactivatedviathecontrolunitoftheDynamicStabilityControl(DSC).Thereisaparkingbrakebuttononthecenterconsoleforactivatingordeactivatingtheelectricparkingbrake.ThedriverisinformedaboutthecurrentsystemstatusviatheinstrumentclusterKOMBI.

Thebrakepadisappliedwithapreciselycalculatedpreloadforceviatwoactuatorsscrewedontothebrakecalipers.AtemperaturemodelisstoredintheDSCcontrolunitwhichmakesitpossibletodrawconclusionsaboutthebrakedisctemperatures.Asthecontactpressuredecreaseswhenthebrakediscscooldown,thesystemmustadjustthebrakepadsasappropriate,particularlyifthebrakediscsarehot.Thetimeandfrequencyoftheadjustmentvariesdependingontheinitialtemperaturecalculated.

Whentheelectricparkingbrakeisopened,theactuatorsaremovedbackonlyuntilthebrakepadshavereachedtheircorrectlysetclearance.Duetothisreadjustmentfunction,theactuatorsmustbemovedbackbeforeexchangingthebrakepadsinService.Forthedetailedprocedure,refertothecurrentrepairinstructions.


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ActuatorforelectricparkingbrakeintheG12

Index Explanation1 Beltdrive2 Planetarygears3 Spindlenut4 Brakecaliper5 Electricmotor(DC)

Thereisanelectricmotorwithbeltdriveandplanetarygearonthehousingofthecombinedbrakecaliperwithelectricparkingbrake.Whentheelectricmotorisactivated,theforceistransmittedviathebeltdriveandplanetarygeartothespindlenut.Thespindlenutgeneratestherequiredstroketoapplythebrakepad.ThecontrolunitoftheDynamicStabilityControlcandeterminethepreloadforceonthebasisoftheriseincurrentoftheelectricmotor.

Whencarryingoutservicingwork,anextendedspindlenutcanbetravelledbacktoitsinitialpositionasfollows:

• Specialtoolformechanicallyturningback• Servicefunction“Workshopmode”intheBMWdiagnosissystemISTA

4.2.1.Functions

Dynamicemergencybraking

Iftheparkingbrakebuttonisoperatedduringthejourneyaboveadefineddrivingspeed,theDSCunitinitiatesadynamicemergencybrakingoperation.Apressurebuild-upoccursinall4wheelbrakesduetoactivationofthe6-pistonpumpandthechangeovervalvesintheDSCunit.Thesliplimitsofallwheelsaremonitoredwiththeassistanceofthefourwheelspeedsensorstoensureastablebraking


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operationuntilthevehiclecomestoastandstill.Thetwoactuatorsoftheelectricparkingbrakeareactivatedassoonasthevehiclecomestoastandstill.Thevehicleisthensecuredtopreventitfromrollingawayonlybymeansoftheparkingbrake.

Automaticreleaseoftheparkingbrake

Thisfunctionallowsthedrivertodriveoffwhentheparkingbrakeisactivatedwithoutoperatingtheparkingbrakebuttontoreleasethebrake.

Prerequisitesforreleasingtheelectricparkingbrake:

• Driver'sdoorisclosed• VehicleconditionDRIVING• Electricparkingbrakeactuated• Drivepositionengaged• Acceleratorpedaloperated

4.2.2.BraketeststandTheDynamicStabilityControl(DSC)hasarollermodesothatthebrakingpoweroftheelectricparkingbrakecanbecheckedonabraketeststand.Whenrollermodeisactivated,thevehicleisbrakedviatheactuatorsoftheelectricparkingbrakewhentheparkingbrakebuttonispressed.ADSCpressurebuild-upinthe4wheelbrakesdoesnottakeplace.Thismakesitpossibletodeterminethebrakeforcesoftheelectricparkingbrake.

IntheG12,rollermodeisautomaticallydetectedonthebasisofaplausibilitycheck(wheelspeedcomparison).Thedetectiontakesamaximumof5seconds(canberecognizedbyslowflashingoftheredparkingbrakeindicatorlight).

Afteractivationofteststandmodethesystemisinteststandmode.Thisconditionisacknowledgedbytheindicatorlightoftheparkingbrakestartingtoflashatafrequencyof1Hz.Theparkingbrakecanbeappliedin5stagesusingtheparkingbrakebutton.Inthiscase,thebrakingvariesbetweentheminimumbrakingpowerinthefirststageandthemaximumbrakingpoweroncetheparkingbrakebuttonhasbeenpressedfivetimes.Ifthebuttonisoperatedcontinuously,thesystemincreasesthebrakingpowerautomaticallyincrementallyuptothemaximumbrakingpower.Theflashingfrequencyoftheparkingbrakeindicatorlightchangesfrom1Hzto3Hzwhentheparkingbrakebuttonispressedinteststandmode.

Thefollowingpointsmustbeobservedduringthetest:

• Donotpresstheaccelerator• DrivepositionN(neutral)• Donotpressthefootbrake


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4.3.Serviceinformation

4.3.1.ServicebrakesThestatusofthebrakepadscannotbereadoutpermanentlyviatheCentralInformationDisplay(CID).

ThefollowinggraphicshowsthevehiclestatuswithoutandwithinformationaboutthestatusofthebrakepadsontheCentralInformationDisplay(CID).

CIDmessageonvehiclestatusintheG12

Index ExplanationA BrakepadwearsensorwithinlimitsB Brakepadwearsensoroutsidelimits1 Vehiclestatus2 OKEngineoil3 OKBrakefluid4 OK§vehicleinspection5 OKVehiclecheck6 Brakepadsrear(padwearshortlybeforethewearlimit)

TheG12isequippedwithaone-stagebrakepadwearsensor.Novehiclestatusaboutthecurrentstatusofthebrakepadsisoutputaslongasthissensorhasnotbeengroundbythebrakedisc.


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Beforethewearlimitofthebrakepadisreached,thesensorwireoftheone-stagebrakepadwearsensoriscutthroughbytherotatingbrakediscwhiledriving.Asfromthispoint,thevehiclestatusofthebrakepadscanbecheckedontheCentralInformationDisplay(CID).Theremainingdistanceuntilthewearlimitofthebrakepadisreachedis4000-5000km/2500-3100miles,dependingondrivingstyle.

Inaddition,thedriverisinformedabouttheconditionofthebrakepadsbymeansofthefollowingwarnings.

Remainingdistance YellowCheckControlmessage

RedCheckControlmessage

<2000km/<1200miles X0km/0miles X

Thecurrentrepairinstructionsmustalwaysbeobservedinordertoavoidinterferencenoisesafterbrakepadreplacement.

4.3.2.Parkingbrake

Replacingbrakepads

Inordertoreplacethebrakepadsoftherearparkingbrakecalipers,itisfirstnecessarytoturnbackthedrivespindleinthebrakecaliper.ThiscanbedoneeithermanuallyusingaspecialtoolorusingtheBMWdiagnosissystemISTA.TheparkingbrakebuttonisblockedtopreventuseafteractivationofworkshopmodeviatheBMWdiagnosissystemISTA.Thispreventsinjuryduringthebrakeservice.Theparkingbrakebuttonisenabledagainatthestartofdrivingorafterexitingworkshopmode.

Afterenablingviathespeedthresholdof3km/h/1.8mph,theparkingbrakemustbere-initializedbybuttonoperation(apply/releasebrake).

Emergencyrelease

Itispossibletomechanicallyturnbackthedrivespindletoreleasetheparkingbrakeafterremovingtheactuatorhousingfromthebrakecaliper.Topreventaccidents,thevehiclemustfirstbesecuredtopreventitfromrollingaway.

Emergencyreleaseoftheelectricparkingbrakeispermittedonlybycorrespondinglytrainedpersonnel.

G12ChassisandSuspension5.Wheels/Tires

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TheG12willbeequippedinthestandardequipmentconfigurationwithrun-flattires.Asparewheelisavailableasoptionalequipment.

Components Standardequipment OptionalequipmentRun-flattires XSparewheel(OE300) X

TiresoftheG12

Index ExplanationA Tireswithoutemergencyrunningproperties(NotforUS)B Run-flattires

Intheeventoftirepressurelossinarun-flattire,thecustomercanstilldriveatarestrictedspeed(max.80km/h/50mph)foraremainingdistancethatisdependentonthevehicleload.Onvehicleswiththeoptionalchassisandsuspensionpackage“ActiveComfortDrive”,thevehicleweightisautomaticallydistributedviatheactiveelectricstabilizerswhendrivingwithanunpressurisedrun-flattiresothattheunpressurisedwheel(<0.5bar)isrelievedtothemaximumpossibleextentandtheintactwheelsloadedcorrespondingly.Thisensuresthatthemaximumpossibleremainingdistancecanbedriven.Themaximumpermittedremainingdistancewithmediumloadis80kilometres/50miles.

Furtherinformationonthefunctionoftheactiveelectricstabilizerisprovidedinthesection“AutobahanPackage”.

Adamagedrun-flattirecanalsobereplacedbyatirewithoutemergencyrunningpropertiesintheeventoftirefailure.However,thetirewithoutemergencyrunningpropertiesmustbereplacedattheearliestopportunitybyarun-flattire.


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5.1.PuncturedetectionsystemsDependingoncountry,theG12isequippedwiththefollowingsystemsforpuncturedetection:

• Tirepressurecontrol(RDC)

5.2.TirePressureMonitorRDCi

SystemoverviewoftirepressurecontrolRDCiintheG12


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Index Explanation1 Wheelelectronics,frontright2 CentralInformationDisplay(CID)(displayoftirepressurespossible)3 Wheelelectronics,rearright4 Remotecontrolreceiver(FBD)5 Wheelelectronics,rearleft6 Instrumentpanel(KOMBI)7 DynamicStabilityControl(DSC)8 Wheelelectronics,frontleft

TheG12isequippedwiththeRDCialreadyfamiliarfromtheF15.TheRDCiisasystemwhichperformsdirectmeasurementandwhichdeterminestherealtirepressuresbymeansofwheelelectronicsineachwheel.UnlikewiththeRDClow,aseparateRDCcontrolunitisnotrequiredfortheRDCi.ThefunctionsoftheRDCiareintegratedintotheDynamicStabilityControl(DSC)controlunit.Theremotecontrolreceiver(FBD)actsasareceiverforthesentreportsofallwheelelectronics.ItthenforwardsthisinformationviabustotheDSCcontrolunit.

ThepreviousRDCisystemsweresuppliedbyContinental.ThesystemsupplieroftheRDCiintheG12isthecompanySchrader.Inordertoensurefault-freeoperationofthesystem,itisessentialthatonlySchraderwheelelectronicsareused.Itisnotpossibletoassumeanyliabilityformalfunctionswiththird-partywheelelectronics.

OntheG12,theresttimesrequiredbythesystembeforethenewwheelelectronicscanbetaught,havechanged.Previously,avehiclewithRDCihadtobestationaryforanuninterruptedperiodofatleast8minutesindependentlyoftheterminalstatusbeforetheDSCcontrolunitacceptedtheIDsofthenewwheelelectronics.

OntheG12,thevehicleconditionisdecisiveforthetimesrequiredbythesystembeforetheIDsofnewwheelelectronicsareacceptedandtaught.Thefollowingtableprovidesanoverviewofthedifferentconditions.

Vehiclecondition 5minutes 17minutesResiding/Awake XDriving X

SothatnewwheelelectronicscanbetaughtbytheDynamicStabilityControl(DSC),astandingtimeofatleast5minutes(Residing/Awake)or17minutes(driving)mustbeobservedafterawheelexchange.

Ifthestandingtimeofatleast5minutes(Residing/Awake)or17minutes(driving)wasnotreachedbeforestartingajourneywithnewwheelelectronics,aCheckControlmessagewillbedisplayedtothedriverafteracertaintime.Inthiscase,thevehiclemustonlyremainstationaryforanuninterruptedperiodoflongerthan5minutesinResiding/Awakemodeor17minutesinDrivingmode.ThenewwheelelectronicswillthenbeautomaticallytaughtbythecontrolunitoftheDynamicStabilityControl(DSC).


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ThevehiclecanalsobeinthevehicleconditionDrivingwhentheenginehasbeenswitchedoffbytheautomaticenginestart-stopfunctionMSA.

Thesystemmustbere-initializedintheeventofchangesinthetirepressuresaswellasafterwheelexchange.InitializationofthenewtirepressurescanbeperformedusingthecontrollerontheCentralInformationDisplay(CID).

5.2.1.Wheelelectronics

WheelelectronicsfromSchraderintheG12

Thewheelelectronicsareinthefollowingmodes,dependingonthesystemstatus:

• Sleepmode• Teach-inmode• Readinessmode

TherearealsochangesinthetransmissionmodesoftheSchraderwheelelectronicsincomparisonwiththetransmissionmodesofthewheelelectronicsfromContinental.Inordertoguaranteethelongestpossiblebatterycapacity,thewheelelectronicsrequirelongerstandingtimesbeforetheyswitchtoteach-inmode.

After15minutesinrestmode(wheelstandstill),thewheelelectronicsstarttotransmitinteach-inmodeassoonastheyareacceleratedtoaspeedfasterthanaround20km/h.Inteach-inmode,thereportsaresenttotheDSCcontrolunitevery15secondsforapproximately9minutes(40reports).Transmissioninteach-inmodeallowstheDSCcontrolunittocalculatetheinstallationpositionoftherespectivewheelelectronics.Thewheelelectronicswillstarttotransmitinreadinessmodeifawheel


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setwaschangedfromonevehicletoanotherwithoutthewheelsethavingbeeninrestmode(wheelstandstill)foranuninterruptedperiodofmorethan15minutes.Teachingofthewheelelectronicsisnotpossibleinreadinessmode.

Balancingofthewheelsetshortlybeforefittingonthevehicleisnotaproblem.Sinceonlyasmallnumberofreportsaretransmittedinteach-inmodeduringbalancing,theremainingreportsaresufficienttoreliablyteachthewheelelectronics.

ThebatterystatusofthewheelelectronicscanbereadoutviatheBMWdiagnosissystemISTA.Theremainingbatterylifeisspecifiedinpercent.

DetailedinformationontheoperatingprincipleoftheRDCiisprovidedintheTrainingReferenceManual“I01CompleteVehicle”.

G12ChassisandSuspension6.DrivingStabilityControl

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BusoverviewG12


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Index ExplanationACC ActivecruisecontrolACSM CrashSafetyModuleAHM Trailermodule(NotforUS)AMPT AmplifierTop(tophighfidelityamplifier)ASD ActiveSoundDesignBDC BodyDomainControllerCON ControllerDDE DigitalDieselElectronics(NotforUS)DME DigitalMotorElectronicsDME2 DigitalEngineElectronics2DSC DynamicStabilityControlEARSVH ElectricactiverollstabilizationrearEARSVV ElectricactiverollstabilizationfrontEGS ElectronictransmissioncontrolEPS ElectromechanicalPowerSteeringFLA High-beamassistantFLER FrontalLightElectronicsRightFLEL FrontalLightElectronicsLeftFZD RooffunctioncenterGWS GearselectorHEADUNIT HeadunitHKARearclimatecontrol

Automaticrearair-conditioningandheating

HKFM TailgatefunctionmoduleHSR RearaxleslipanglecontrolIHKA Integratedautomaticheating/airconditioningKAFAS Camera-baseddriversupportsystemsKOMBI InstrumentpanelLEM LightEffectManagerNFC NearFieldCommunicationNVE NightVisionElectronicsPCU PowerControlUnitPMA ParkingmanoeuvringassistantRFK ReversingcameraRSE RearSeatEntertainment


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Index ExplanationRSL RadarSensorLeft(avoidanceassistant)RSR RadarSensorRight(avoidanceassistant)SAS OptionalequipmentsystemSCR SelectiveCatalyticReductioncontrolunit(NotforUS)SMBF Seatmodule,passengerSMBFH Seatmodule,passenger,rearSMFA Seatmodule,driverSMFAH Seatmodule,driver,rearSPNMHL SeatpneumaticsmodulebackleftSPNMHR SeatpneumaticsmodulebackrightSWW Lanechangewarning(main)SWW2 Lanechangewarning(secondary)TCB TelematicCommunicationBoxTRSVC ControlunitforrearviewcameraandSideViewVDP VerticalDynamicPlatformVM VideoModule(NotforUS)VTG VTGcontrolunitWCA WirelesschargingtrayZGM Centralgatewaymodule

ThecontrolunitsthatarerelevanttodrivingdynamicsareinterconnectedviatheFlexRaybus.Thisbusischaracterizedaboveallbyitshighdatatransferrateof10MBit/s.

Themostimportantsystemsandtheirfunctionsaredescribedinmoredetailbelow.


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6.1.DynamicStabilityControl(DSC)AlongsidetheVerticalDynamicsPlatform(VDP)controlunit,theDynamicStabilityControl(DSC)representsthecoreelementofthedrivingdynamicscontrolsystemsusedtoincreaseactivesafety.Itoptimizesdrivingstabilityinalldrivingconditionsandalsotractionwhendrivingoffandaccelerating.Italsoidentifiesunstabledrivingconditionssuchasundersteeringoroversteeringandhelpsmaintainthevehicleonasteadycourse.

InstallationpositionofDynamicStabilityControl(DSC)intheG12

Index ExplanationA DSCunit1 DSCcontrolunit2 BrakelineconnectionsattheDSChydrauliccontrolunit3 Returnpump4 Bracket

TheDynamicStabilityControl(DSC)islocatedinthefrontlowerareaofthevehicle.ThemanufacturerdesignationisTRWDSC-EBC460.Duetothedifferentconnectiondiametersofthebrakelines,channelconfusionofthevarioushydrauliclinesisnotpossible.


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DSCunitintheG12

Index ExplanationA DSChydraulicunitB DSCcontrolunit1 Pressuresensors2 Hydraulicdampingelements3 Returnpumpactivation4 Solenoidvalves(12x)5 Controlunitconnector6 Solenoidvalvecoils(12x)

TheDSCcontrolunitandtheDSChydrauliccontrolunitarescrewedtogether.TheDSCcontrolunitcanbereplacedindividuallytoreduceservicingcosts.

Inolderseries,thedifferentdrivingdynamicssystemsareconnectedviatheIntegratedChassisManagement(ICM)controlunit.ThecontrolunitoftheDynamicStabilityControl(DSC)intheG12hasanadditionalstorageelement(blackbox)inwhichsomeofthefunctionsoftheIntegratedChassisManagement(ICM)arestored.Thedifferentdrivingdynamicscontrolsystemsarecoordinatedperfectlybymeansofthealgorithmsstoredintheblackbox.

Thefunctionsofthetirepressurecontrol(RDC)andelectricparkingbrake(EPB)wereintegratedintheDSCcontrolunit.


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6.1.1.Hydrauliccircuitdiagram

HydrauliccircuitdiagramofTRWDSC-EBC460

Index ExplanationA InstalledonlyonhybridversionB OnlyforoptionalequipmentactivecruisecontrolwithStop&Gofunction1 Hydraulicdampingelements2 6-pistonpump3 DSCpressuresensor4 Brakemastercylinder5 Brakefluidexpansiontank6 Brakeservo7 BrakepedaltravelsensorAV Exhaustvalves


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Index ExplanationEV IntakevalvesHL RearaxleonleftHR RearaxleonrightTV SeparatorvalvesUPS ChangeovervalvesVL FrontaxleonleftVR Frontaxleonright

DifferentDSCversionsareuseddependingonthedrivetypeandequipmentrange.Inthehybridversion,thereisanadditionalbrakepedaltravelsensoronthefootbrakelever.

Ifthevehicleisequippedwiththeoptionalequipment“ActivecruisecontrolwithStop&Gofunction”,thereare2additionalpressuresensorsinthehydraulicunit.

6.1.2.FunctionsThefollowingtableprovidesanoverviewofthedifferentfunctionsoftheDSCunit.

Function ExplanationAntilockBrakeSystem(ABS)

Preventsblockingofindividualwheelswhenbrakingthroughtargetedmodulationofthebrakepressures.Vehiclesteerabilityismaintained.

DynamicStabilityControl(DSC)

Ifthevehiclestartstoundersteeroroversteer,itisstabilizedbytargetedbrakeinterventionsatindividualwheels.

DynamicTractionControl(DTC)

ThisisaspecialmodeoftheDynamicStabilityControl(DSC).IninteractionwithASCandDSC,thismodefeaturesextendedinterventionthresholdsandpermitsanevensportierdrivingstylewithoutinterventionsonnormalsurfacesaswellasmaximumpropulsiononloosegroundsuchassnow,sandorcoarsegravel.

CorneringBrakeControl(CBC)

Preventsthevehiclefromturninginwhenitisbrakedlightlyunderhighlateralaccelerationforcesbymeansofasymmetricalcontrolofthebrakepressure.Thecorneringstabilityisimproved.

AutomaticStabilityControl(ASC)

Preventsthedrivewheelsfromspinningbytargetedbrakingofthesewheelsandadaptationofthedrivetorquedeliveredbytheengine.Vehiclepropulsionisoptimizedasaresultanddrivingstabilityismaintained.

DynamicBrakeControl(DBC)

Intheeventofpanicbrakinginitiatedbythedriver,thesystemsupportsthedriverbyautomaticallyimmediatelyapplyingthemaximumbrakepressuretoensurethebestpossibledeceleration.

AutomaticDifferentialBrake(ADB-X)

Replicatesthefunctionofadifferentiallock.Ifawheeldisplaysatendencytospin,thiswheelisautomaticallybrakedsothatpropulsioncanstillbeachievedviatheotherwheelofthedrivenaxle.

Trailerstabilizationcontrol

Automaticallydetectswhenavehiclewithtrailerisstartingtosnake,stabilizestheoutfitbytargetedbrakeinterventionsandsimultaneouslydeceleratesittoanuncriticalspeedforsnaking.


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Function ExplanationBrakestandby Buildsupamoderatebrakepressureinthesystemwhenthedrivertakes

hisfootofftheacceleratorpedalveryquickly.Thebrakepadsareappliedslightlyasaresult.Thebrakingeffectthenactsmorequicklyifthedriverthenperformspanicbraking.

Drybyapplyingbrake Dependingonoperationofthewiper,appliesthebrakepadsgentlyatintervalsinordertodrythebrakediscs.Thebrakingeffectissignificantlyimprovedbythiswhenthevehicleisbraked.

Fadingsupport Supportsthedriverwhenbrakingifthebraketemperaturehasbecomeveryhighduetoanextremedrivingstyleandthedesireddecelerationcanbeachievedonlybyapplyingahigherbrakeforce.

Drive-offassistant Holdsthevehicleforapproximately1.5sonuphillgradientswhenthedriverreleasesthebraketodriveoff.Thisallowsthedrivertodriveoffcomfortablywithoutthevehiclerollingawayonitsown.

AutomaticHold Automaticallyholdsthevehicleafterithascometoastandstillwithoutitbeingnecessarytostillpressthebrakewhenthedrivepositionisselected.Thebrakeisautomaticallyreleasedwhentheacceleratorpedalispressedandthevehicledrivesawaynormally.Thefunctioncanbeswitchedonandoffbymeansofabutton.

Ifatrailertowhitchisretrofitted,thefunction“trailerstabilizationlogic”mustbeencodedintheDSCcontrolunit.


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6.1.3.Systemwiringdiagram

SystemwiringdiagramfortheDynamicStabilityControl(DSC)intheG12


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Index Explanation1 Brakepadwearsensor,frontleft2 Wheel-speedsensor,frontleft3 Powerdistributionbox,enginecompartment4 Wheel-speedsensor,frontright5 Powerdistributionbox,frontright6 BodyDomainController(BDC)7 Rearrightpowerdistributionbox8 Wheelspeedsensor,rearright9 Brakepadwearsensor,rearright10 Actuator,electricparkingbrakerearright11 Actuator,electricparkingbrakerearleft12 Wheelspeedsensor,rearleft13 CrashSafetyModule(ACSM)14 ButtonforelectricparkingbrakeandforAutomaticHoldfunction15 DSCbutton16 Brakelightswitch17 Steeringcolumnswitchcluster18 Instrumentpanel(KOMBI)19 Brakefluidlevelswitch20 DynamicStabilityControl(DSC)


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6.2.Steering

OverviewofsteeringintheG12

Index Explanation1 Steeringwheel2 Uppersteeringcolumnwithsteeringcolumnadjustment3 Controlunitforsteeringcolumnadjustment4 Lowersteeringcolumnwithslidingpiece5 Trackrodend6 Trackrod7 Steering-torquesensor8 EPScontrolunit(ElectronicPowerSteering)9 ElectricmotorforEPS(ElectronicPowerSteering)

Inelectricsteeringsystems,thesupporttorqueisgeneratedbymeansofanelectricmotor.


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Inadditiontothepuresupportfunction,thefrontwheelscaninprinciplebemadetoperformanysteeringmovementindependentlyofthemanualtorqueappliedatthesteeringwheel.ThissystemisthereforeaprerequisiteforrealizationofalargenumberofassistancefunctionssuchastheParkingManoeuvringAssistant(PMA).

TheElectronicPowerSteering(EPS)permitsareductionintheaveragefuelconsumptionofapproximately0.3lper100km/62miles.Afurtheradvantageisthatnooilisneededforsteeringassistance.

6.2.1.SteeringwheelItispossibletochoosebetween3differentsteeringwheeldesigns.

SteeringwheelversionsintheG12

Index ExplanationA SportssteeringwheelwithshiftpaddlesB LuxurysteeringwheelC Standardsteeringwheel(NotforUS)

Intheluxuryversion,theleatherrimfeaturesawoodinlayleathersteeringwheel.Thedrivercanoperatethevariousassistanceanddriverinformationsystemsbymeansofthemultifunctionswitches.

Steeringwheeldiameterofthedifferentversions:

• Sportssteeringwheel=382mm• Luxurysteeringwheel=384mm(NotforUS)• Standardsteeringwheel=385mm(NotforUS)


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Additionalfunctionsareoptionallypossible:

• Heatedleatherrim.• Transmissionofhapticvibrations(steeringwheelvibration)

Forassistancesystemssuchaslanedepartureorlanechangewarning.• Hands-Offdetection

Forthetrafficjamassistantfunction.• Shiftpaddles

ForthemanualshiftfunctionwiththeautomaticSporttransmission(SA2TB).

6.2.2.Steeringcolumnadjustment

SteeringcolumnadjustmentintheG12


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Index Explanation1 Electricmotor2 Spindle3 Controlunitforsteeringcolumnadjustment4 Steeringshaft

Thesteeringcolumnwithelectricallongitudinalandheightadjustmentallowsthedrivertoassumeanoptimumsittinganddrivingpositionthroughseamlessadjustmentofthesteeringwheelposition.

Adjustmentrange:

• Heightadjustment=+/-20mm• Forward/backadjustment=-20mm/+40mm

6.2.3.VersionoverviewTheG12isequippedwiththefollowingdifferentsteeringsystems:

• Standardsteering12V• IntegralActiveSteering12V• IntegralActiveSteering24V

Components Standardsteering12V

IntegralActiveSteering12V

IntegralActiveSteering24V

ElectronicPowerSteeringwithnormalrackgeometry

X

ElectronicPowerSteeringwithvariablerackgeometry

X X

12 Vbattery X X X12Vauxiliarybattery XPowerControlUnit(PCU)(DC/DCconverter150W)

X

Rearaxleslipanglecontrol(HSR)

X X


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Thefollowinggraphicshowstheinstallationpositionsofthedifferentsystemcomponents.

OverviewofthesteeringsystemsoftheG12

Index Explanation1 ElectromechanicalPowerSteering1a Conventionalrackgeometry(standardsteering)1b Variablerackgeometry(IntegralActiveSteering)2 PowerControlUnit(PCU)(onlyfor24Vsteering)3 Rearaxleslipanglecontrol(HSR)(IntegralActiveSteering)4 12Vauxiliarybattery(onlyfor24Vsteering)5 Separatingelement(onlyfor24Vsteering)6 12 Vbattery7 DynamicStabilityControl(DSC)

Withthestandardsteering,theG12isequippedwithconventionalelectromechanicalpowersteering(12V)withnormalrackgeometry.


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TheoptionalequipmentIntegralActiveSteeringnownolongerconsistsofanactivesteeringsystemwithvariableratiotransmission,buthasbeenreplacedbyanelectromechanicalpowersteeringsystemwithvariablerack(sportsteering)aswellasrearaxleslipanglecontrol(HSR).Dependingontheaxleloadsofthefrontvehicleend,a12Vor24Vsteeringsystemisused.Therearaxleslipanglecontrol(HSR)alwaysoperateswitha12Vvoltage.

ThefollowingtableprovidesanoverviewofthedifferentvoltagelevelsoftheelectricsteeringintheoptionalequipmentIntegralActiveSteering.

Model Engine Rear-wheeldrivewithIntegralActiveSteering

All-wheeldrivewithIntegralActiveSteering

740i B58 12V —750(x)I N63 24 V 24 V

6.2.4.IntegralActiveSteering

Frontaxle

Ratioofthevariablerackgeometry(OEIntegralActiveSteering)intheG12


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Index ExplanationA Moreindirectsteeringgearratiointhecenterpositionof

thevariablerack(0°-45°)B Transitionalrange(45°-130°)C Directsteeringgearratiooutsidethecenterpositionof

thevariablerack(>130°)X Steeringanglein°y Steeringgearratioinmm/steeringwheelturn1 Variablerackgeometry(IntegralActiveSteering)

ThevariablesteeringgearratiointheoptionalequipmentIntegralActiveSteeringisaccomplishedbythegeometry/pitchofthetoothedgearoftherack.Aroundthecenterpositionofthesteeringgear,thesteeringsystembehavesaccuratelywithsteadydirectionalstability.Asthesteeringanglemovesawayfromthecenterposition,theratiobecomesincreasinglymoredirect.

SteeringangleoftheIntegralActiveSteeringonthefrontaxleoftheG12

Index ExplanationA Moreindirectsteeringgearratio(variablerackgeometry)B Directsteeringgearratio(variablerackgeometry)


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Rearaxle

Rearaxleslipanglecontrol(HSR)intheG12

Index Explanation1 Trackcontrolarmmounts2 Electricmotor3 HSRcontrolunit(rearaxleslipanglecontrol)4 Spindlepositionsensor(PLCDsensor)5 Permanentmagnet6 Carrierplate

Therearaxleslipanglecontrol(HSR)mountedontherearanglepermitsamaximumsteeringangleoftherearwheelsof+/-3°.Asaresult,itwaspossibletoreducetheturningcirclebyapproximately1mincomparisonwithvehicleswithoutrearaxleslipanglecontrol(HSR).Therearaxleslipanglecontrolisavailablefromaspeedofapproximately5km/h/3mphuptothemaximumspeed.

TherequesttoadjustthesteeringangleattherearaxleisissuedbytheDynamicStabilityControl(DSC).Aspindledriveinsidethecomponentisrotatedviatheelectricmotor.Thisproducesalinearmovementatthetwotrackcontrolarms.Usingthepositionsensor,thecontrolunitoftherearaxleslipanglecontrol(HSR)candeterminethelineardisplacementandthuscalculatethesteeringangleofthetworearaxlewheels.

Thespindledriveoftherearaxleslipanglecontrol(HSR)isself-inhibiting.Thismeansthatthevehiclehastheidenticaldrivabilitytoavehiclewithoutrearaxleslipanglecontrol(HSR)intheeventofsystemfailure.


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Aspecialfixtureisrequiredforalignmentinordertoassemblethecarrierplates.ThisisnotavailableinService.Forthisreason,thecarrierplatesontherearaxleslipanglecontrol(HSR)mustnotbeundone.Ifthisisnotobserved,thewheelalignmentontherearaxlewillbecomeincorrectlyadjusted.

Thecarrierplatesoftherearaxleslipanglecontrol(HSR)mustnotbeundoneinService

Operatingstrategy

InputandoutputdiagramoftheIntegralActiveSteeringintheG12

Index Explanation1 DynamicStabilityControl(DSC)2 Rearaxleslipanglecontrol(HSR)3 Yawrateandlateralacceleration(ACSM)4 Wheelspeeds5 Steeringangle(EPS)


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OperatingstrategyoftheIntegralActiveSteeringintheG12

Index ExplanationA OppositesteeringB Parallelsteering

Inthespeedrangeuptoapproximately60km/h/37mph,therearaxleslipanglecontrol(HSR)steersintheoppositedirectiontothesteeringanglesofthefrontaxlesteering.Thispermitsincreasedvehiclemanoeuvrability.

Asfromthespeedrangeofapproximately60km/h/37mph,therearaxleslipanglecontrol(HSR)steersinthesamedirection.Thisimprovesthedirectionalstabilityofthevehicle.


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Drivingdynamicscontrolinterventionswhencornering

Whenchanginglanesquickly,allvehicleshaveatendencytoproduceasignificantyawresponseandcansometimesstarttooversteer.IftheDynamicStabilityControl(DSC)detectsadeviationbetweenthedriverwishandvehicleresponse,thevehicleisstabilizedbymeansofasteeringinterventionattherearaxle.Thespeedofthestabilizinginterventionissuchthatitishardlydiscerniblebythedriver.ItispossibletolargelydowithoutdeceleratingDSCbrakeinterventions.Asaresult,thevehicleismorestableandthedrivingdynamicsarepreserved.

PossibledrivingdynamicsinterventionsoftheDSCandIntegralActiveSteeringwhencornering

Index ExplanationA Preventionofundersteerbybrakeinterventionsatindividualwheels(DSC)B Preventionofundersteerbysteeringinterventionsattherearaxle(HSR)M Yawmomentactingonthevehicleduetoaninterventionbythedriving

dynamicscontrol1 Courseofanundersteeringvehicle2 Courseofavehiclewithneutraldrivability3 Individualbrakemodulation(DSC)4 Steeringinterventionattherearaxle(HSR)

Ifthedriverunderestimatesabendwhendrivingrapidly,hemaybesurprisedbysuddenundersteer.Therearaxleslipanglecontrol(HSR)canalsoperformacorrectiveinterventioninundersteersituationsandthusadditionalincreasesactivesafety.


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Drivingdynamicscontrolondifferentsurfaces

Hardbrakingmanoeuvresonroadwaysthatareslipperyononesidemakethevehicleyawtothevehiclesidewithmoregrip.Intheeventofemergencybraking,thedriverofaconventionalvehiclemusttakecorrectiveaction.Withthisso-calledµ-splitbraking,theDynamicStabilityControl(DSC)providesastabilizingyawmomentviaasteeringinterventionattherearaxle.

µ-splitbrakingmanoeuvreswithdifferentdrivingdynamicssystems

Index ExplanationA VehiclewithoutDSCB VehiclewithDSCC VehiclewithDSCandrearaxleslipanglecontrol(HSR)

(optionalequipmentIntegralActiveSteeringSA2VH)

FurthertoA)WithoutDSC

WhenbrakingwithavehiclewithoutDSC,maximumbrakeforceissupportedonthedrysideoftheroadandonlylowbrakeforceonthewetoricyside.Ananti-clockwiseyawmomentisproducedwhichcanleadtothevehicleskiddingtotheright.

FurthertoB)WithDSC

WhenbrakingwithavehicleequippedwithDSC,thebrakeforcesatthewheelsaremeteredsothattheyawmomentactingonthevehicleisreduced.Thevehiclethereforeremainscontrollable.Thestoppingdistancemaybeincreasedslightly.


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FurthertoC)WithDSCandrearaxleslipanglecontrol(HSR)

WhenbrakingwithavehicleequippedwithDSCandrearaxleslipanglecontrol(HSR)(optionalequipmentIntegralActiveSteeringSA2VH),theDSCcontrolunitcalculatesthesteeringanglefortherearwheels.Theactuatorsoftherearaxleslipanglecontrol(HSR)convertthecalculatedsteeringangleintoanactivesteeringangleatbothrearwheels.Theresultantstabilizingyawmomentallowsthemaximumbrakeforcestobeappliedinordertoachievetheshortestpossiblestoppingdistance.Theperfectinteractionofsteeringandbrakeinterventionthereforeincreasesactivesafetyandenhancesthedrivingdynamicsofthevehicle.

6.2.5.ServiceinformationIntheeventofarepair,thesteeringgearcanbefullylowered.Thiseliminatestheneedforcomplexaxledisassemblyandrepaircostsarereducedsignificantly.

Steeringangle

Thesteeringangleiscalculatedbythecontrolunitoftheelectromechanicalpowersteeringusingtherotoranglesensor.Intheeventofalossofthevoltagesupply,thisstoredvalueislostandmustbetaughtagain.Thiscanbedonestaticallybyturningthewheelstotherightandleftwiththeenginerunningordynamicallywhendrivingslowly.

Drivingwithsnowchains

SettingmenufordrivingwithsnowchainsintheG12

Index ExplanationA SnowchainmodedeactivatedB Snowchainmodeactivated


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Inordertoavoiddamagetothewheelarcheswhendrivingwithsnowchains,therearaxleslipanglecontrol(HSR)mustbefixedinstraight-aheadposition.ThedrivercandothismanuallyusingthecontrollerontheCentralInformationDisplay(CID).Themaximumpermittedspeedis50km/h(31mph)hisspeedisexceeded,therearaxleslipanglecontrol(HSR)switchesonagainautomatically.


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6.2.6.Systemwiringdiagram

24Vsteering

Systemwiringdiagramfor24VsteeringintheG12


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Index Explanation1 DynamicStabilityControl(DSC)2 Wheel-speedsensor,frontleft3 Enginecontrolunit(DME)4 ElectronicPowerSteering(electromechanicalpowersteering)(EPS)5 Steering-torquesensor16 Steering-torquesensor27 Wheel-speedsensor,frontright8 Powerdistributionbox,frontright9 BodyDomainController10 Wheelspeedsensor,rearright11 Rearrightpowerdistributionbox12 PowerControlUnitPCU(DC/DC150W)13 Separator14 12Vauxiliarybatteryfor24Vsteering15 Positivebatteryterminaldistributor16 Wheelspeedsensor,rearleft17 CrashSafetyModule(ACSM)18 Brakelightswitch19 Steeringcolumnswitchcluster(SZL)20 Instrumentpanel(KOMBI)


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Rearaxleslipanglecontrol(HSR)

Systemwiringdiagramforrearaxleslipanglecontrol(HSR)intheG12


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Index Explanation1 DynamicStabilityControl(DSC)2 CrashSafetyModule(ACSM)3 BodyDomainController(BDC)4 Rearrightpowerdistributionbox5 Positivebatteryterminaldistributor6 Rearaxleslipanglecontrol(HSR)


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Electricallyadjustablesteeringcolumn

SystemwiringdiagramforelectricallyadjustablesteeringcolumnintheG12


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Index Explanation1 Powerdistributionbox,frontright2 BodyDomainController(BDC)3 Steeringcolumnswitchcluster(SZL)4 Buttonforsteeringcolumnadjustment5 Memoryswitch6 Controlunitforsteeringcolumnadjustment7 Electricmotor(DC)8 Electricmotor(DC)

6.3.ElectronicDamperControl(EDC)Inordertomeetthehighcustomerdemandswithrespecttocomfortanddrivingdynamics,theG12isequippedasstandardwithElectronicDamperControl(EDC).Theelectronicallycontrolledshockabsorbersformaunitwiththerespectiveairsuspensionstrutandcannotbereplacedseparately.Thereare2electriccontrolvalvesoneachshockabsorberwhichallowthecompressionandreboundstagesoftheregulatedshockabsorberstobeadjustedseparatelyfromeachother.Thismakesitpossibletoperfectlycounteractthevibrationsofthebodyandwheels.Thisincreasessafety,comfortanddrivingdynamics.

6.3.1.ShockabsorberdesignTheshockabsorbersaresingle-tubegas-filledshockabsorbers.Thegascushionconsistsofnitrogenatapressureof16.5bar.Thisispressedtogetherandthuscompressedfurtherbytheoildisplacedwhenthepistonrodisretracted.Thehighgaspressurepreventsfoamingoftheoilunderalloperatingconditionsandthusguaranteesoptimumshockabsorberoperation.Inaddition,thehighgaspressureensuresthatthepistonrodispressedoutwithaforceofapproximately400N(~40kg).Compressionoftheshockabsorberbyhandisthereforehardlypossible.

Thefollowinggraphicshowstheinternaldesignofanelectricallyregulatedshockabsorber.


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DesignofEDCshockabsorberintheG12

Index Explanation1 Pistonrod2 Workingchamber3 Overflowduct4 Controlvalve,compressionstage5 Comfortvalve,compressionstage6 Comfortvalve,reboundstage7 Controlvalve,reboundstage8 Gaspressurechamber


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Index Explanation9 Dividingpiston10 Balancingchamber11 Bottomvalve12 Workingchamber13 Workingpiston

Inordertopermitasportydrivingstyleongoodroadswhilestillabsorbingbumpsonroughroadsurfacesascomfortablyaspossible,theoilflowinsidetheshockabsorbercanbevariablyadjusted.Thechangesintheoilflowchangetheforcesactingontheshockabsorber.

Theshockabsorberhas2controlvalves,whichallowseparateadjustmentofthedampingforceforrebound(reboundstage)andcompression(compressionstage).

Thecontrolvalvesadjustthedampingforcebychangingarestrictorcross-sectionthroughwhichanoilflowispressed.Thefollowingrelationshipexistsbetweentherestrictorcross-sectionanddampingforce:

• Largerestrictorcross-section=lowdampingforce.• Smallrestrictorcross-section=highdampingforce.

Therestrictorcross-sectionandthusthedampingforcecanbeadjustedseamlessfewmilliseconds.

Compressionstage

Duringcompression,theshockabsorberispushedtogethertelescopicallyandoperatedintheso-calledcompressionstage.

Rebound

Duringrebound,theshockabsorberisextendedtelescopicallyandoperatedintheso-calledreboundstage.

6.3.2.SystemoverviewThedrivingexperienceswitchisusedtoconfiguretheshockabsorberadjustmentsetting.Itispossibletochoosebetweenasportilyfirmorcomfortablysoftchassisandsuspensionsetup.Thefollowingtableprovidesanoverviewofthesettingoptions.

Drivingmode CharacteristicsCOMFORTPLUS ComfortableComfort/ECOPRO BalancedSport Sports


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SystemoverviewoftheElectronicDamperControl(EDC)

Index Explanation1 ElectronicPowerSteering(electromechanicalpowersteering)(EPS)2 Controlvalvesforshockabsorberadjustment,frontright3 Rideheightsensor,frontright4 Controlvalvesforshockabsorberadjustment,frontleft5 Rideheightsensor,frontleft6 DynamicStabilityControl(DSC)7 BodyDomainController(BDC)8 AdvancedCrashSafetyModule(ACSM-High)9 Drivingexperienceswitch10 VerticalDynamicsPlatform(VDP)11 Rideheightsensor,rearright12 Controlvalvesforshockabsorberadjustment,rearright13 Ride-heightsensor,rearleft14 Controlvalvesforshockabsorberadjustment,rearleft

TheElectronicDamperControl(EDC)comprisesthefollowingcomponents:

• 4electricallycontrolledshockabsorberswith2controlvalveseach• VerticalDynamicsPlatform(VDP)controlunit• 4rideheightsensorsfordeterminationofwheelmovement• Sensorclusterfordeterminationofbodymovement(lift,pitchandroll)


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TheVerticalDynamicsPlatform(VDP)controlunitusesvariousdatasuchasbodymovement,transverseandlongitudinalacceleration,steeringangleandtheroadconditiontocalculatewheel-individualcontrolcommandsfortheelectricalcontrolvalvesintheshockabsorbers.Inthisway,thedampingforceoftheindividualshockabsorbersiscontinuouslychangedapproximately100timespersecond.Thismeansthatdemand-basedadjustmentofthedampingforceisalwayspossiblecorrespondingtothedrivingsituation.

Fewervehiclebodymovementsarepermittedifasportierdrivingmodeisselected.Theshockabsorbersareadjustedtoahardsettingmorequicklyandmoreoften.Thisautomaticallyresultsinalossofcomfort.

Inthestandardequipmentconfiguration,informationabouttheverticalbodymovements(pitch,rollandlift)ismadeavailablebytheCrashSafetyModuleACSM-High.Theretractionandextensionspeedsoftheshockabsorbersaredeterminedbymeansoftherideheightsensors.

Ifthevehicleisequippedwiththeoptionalequipment“ActiveComfortDrive”(SA2VS),thereareadditionalwheelaccelerationsensors.TheseareusedamongotherthingsformorepreciseregulationoftheElectronicDamperControl(EDC).

Thefollowingtableshowsthedifferentcomponentsuseddependingonthechassisandsuspensionpackage.

Component Basicchassisandsuspension

ActiveComfortDrive

Wheelaccelerationsensors — XACSM-High X —ACSM-Low — X

Amoredetaileddescriptionoftheoptionalequipment“ActiveComfortDrive”(SA2VS)isprovidedinalaterchapter.

6.3.3.ElectricalshockabsorbercontrolThecontrolvalvesofthereboundandcompressionstagesareactivatedviapulse-widthmodulatedsignalsfromtheVerticalDynamicsPlatform(VDP)controlunit.Thecontrolvalvesareopeninde-energizedcondition.Theshockabsorberisinthemaximumsoftsettinginthiscondition.


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Controlofthecompressionstage

ControlofcompressionstageontheshockabsorberoftheG12

Index ExplanationA ShockabsorbermovementB Oilflow1 Mainvalve,compressionstage2 Workingpiston3 Mainvalve,reboundstage4 Bottomvalve5 Gaspressurechamber6 Controlvalve,reboundstage7 Comfortvalve,reboundstage8 Comfortvalve,compressionstage9 Controlvalve,compressionstage


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Whenthepistonrodisretracted,theoilvolumedisplacedbytheretractingpistonispressedthroughthebottomvalveintothecompensatingreservoirandgeneratesadampingforceatthebottomvalveintheprocess.Theoilvolumedisplacedbytheworkingpistonispressedthroughthecomfortandcontrolvalveofthecompressionstageandthuspassesfromtheworkingchamberbelowtheworkingpistonintotheworkingchamberabovethepiston.Therestrictorcross-sectioninthecontrolvalveadjuststhedampingforce.Theoilflowisforcedthroughthemainvalvewhenthecontrolvalveisclosed.Themaximumpossibledampingforceisthenset.

Controlofthereboundstage

ControlofreboundstageontheshockabsorberoftheG12

Index ExplanationA ShockabsorbermovementB Oilflow1 Mainvalve,compressionstage2 Workingpiston3 Mainvalve,reboundstage


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Index Explanation4 Bottomvalve5 Gaspressurechamber6 Controlvalve,reboundstage7 Comfortvalve,reboundstage8 Comfortvalve,compressionstage9 Controlvalve,compressionstage

Whenthepistonrodisextended,thegaspressureforcesthenecessarycompensationvolumeoutofthecompensatingchamberthroughthebottomvalveintotheworkingchamberbelowtheworkingpiston.Theoilvolumedisplacedbytheworkingpistonispressedthroughthecomfortandcontrolvalveofthereboundstageandthuspassesfromtheworkingchamberabovetheworkingpistonintotheworkingchamberbelowthepiston.Therestrictorcross-sectioninthecontrolvalveadjuststhedampingforce.Theoilisforcedthroughthemainvalveofthereboundstagewhenthecontrolvalveisclosed.Themaximumpossibledampingforceisthenset.

6.4.Anti-rollbarThefollowinganti-rollbarsareusedontheG12dependingonthevehicleequipment:

• StandardequipmentConventionalanti-rollbaronfrontandrearaxles.

• Optionalequipment(“ActiveComfortDrive”SA2VS)ElectricactiverollstabilizationonfrontandrearaxleEARSVV/EARSVH.

ComparisonofconventionalandactiverollstabilizationinstationaryconditionoftheG12


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Index ExplanationA ConventionalpassiverollstabilizationB Activerollstabilizationaq LateralaccelerationFq Transverseforceh Distancebetweenrollaxisandcenterofgravity(leverarm)Ma MomentofactivestabilizerMw RollmomentRA RollaxisSP centerofgravityφ Rollangle

Whencornering,thelateralacceleration(aq)actsatthevehiclecenterofgravity(SP).Thebodyrollsabouttherollaxis(RA),whichisdefinedbythekinematicsofthefrontandrearaxles.Thisresultsintherollangle(φ).

Onvehicleswiththeoptionalequipment“ActiveComfortDrive”(SA2VS),therollmoment(Mw)canbecompensatedsolelybytheactivestabilizersuptoacertainlateralacceleration.Arollangle(φ)buildsuponlywhentherollmoment(Mw)exceedsthecounter-torque(Ma)setbytheactivestabilizer.

Thefollowingdiagramshowsacomparisonofthedifferentrollanglesofbothanti-rollbarsasafunctionofthelateralacceleration.

Rollanglediagramoftheconventionalanti-rollbarandactivestabilizer

Index ExplanationA ConventionalrollstabilizationB Activerollstabilizationaqin[m/s²] Lateralaccelerationinmetrespersecondsquaredφin[°] Rollangleinangulardegrees


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6.5.Standardsuspension

Conventionalanti-rollbarintheG12

Index Explanation1 Rearaxleanti-rollbar2 Frontaxleanti-rollbar

Asstandard,conventionalanti-rollbarsonthefrontandrearaxlesreducetherolltendencyofthebodyduringfastcorneringorfastavoidancemanoeuvres.However,therearealsocomfortlossesinthecaseofone-sidedroadbumpsduetothetorsionspringcharacteristicsofaconventionalanti-rollbar.Ifaconventionalanti-rollbarisexcitedbyapulseatawheelononeside,thisleadstospringoscillationsoftheanti-rollbarsothatthewheelattheotherendoftheanti-rollbaralsoperformsor"copies"theseoscillations.Sincetheanti-rollbarispivot-mountedonthebody,thedriveralsofeelstherolloscillationscausedbythisso-called"copying".

6.5.1.ChassisandsuspensionsetupVehicledrivabilitywhencorneringcanbegreatlyinfluencedbyanti-rollbarsonthefrontandrearaxles.Adecisivefactorhereistherollmomentratiobetweenthefrontandrearvehicleaxles.Thisratiodependsontherespectiveanti-rollbarmomentsofthetwoaxles.

Thefollowingtableprovidesanoverviewofthepossiblerollmomentratiosandtheresultanthandlingofthevehicle.

Anti-rollbar Rollmomentratio Understeer OversteerFrontaxlesoft/rearaxlehard

<50% X

Frontaxlehard/rearaxlesoft

>50% X


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Thefollowinggraphicshowsthepercentagedistributionoftheanti-rollbarmoments(rollmomentratio)ofthefrontandrearaxleswhenconventionalanti-rollbarsareused.

Percentagedistributionoftheanti-rollbarmomentsonavehiclewithconventionalanti-rollbars

Index ExplanationA UndersteeringrollmomentratioMkin[%] Momentdistributionofconventionalanti-rollbarsinpercentvin[km/h] Drivingspeedinkilometersperhour1 Conventionalanti-rollbaronthefrontaxle2 Conventionalanti-rollbarontherearaxle

Withaconventionalanti-rollbar,therollmomentratioisoptimallyadaptedtotherespectivevehicle.Itisaimedtoachievehandlingwithslightundersteer.Fornormaldrivers,anoversteeringvehicleismoredifficulttocontrolthananundersteeringvehicle.

6.6.ActiveComfortDriveThepreviouslyknownoptionalequipmentAdaptiveDriveisreplacedintheG12bytheenhancedsuspensioncontrolsystem“ActiveComfortDrive”.

Thevariousdrivingdynamicscontrolsystemsarenetworkedtogetherintheoptionalchassisandsuspensionpackage“ActiveComfortDrive”inordertoachieveperfectdrivingdynamicscombinedwithhighridecomfort.InformationisreadinfromalargenumberofsensorsbytheVerticalDynamicsPlatform(VDP)controlunitandthecorrespondingcontrolcommandsareoutputtothedifferentactuators.Theaimistoabovealldetectroadbumpsandobstaclesaheadasearlyaspossibleandtoderiveappropriatecounter-measures.


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Thefollowinggraphicprovidesanoverviewoftheoverallsystem.

Systemoverviewoftheoptionalchassisandsuspensionpackage“ActiveComfortDrive”intheG12

Index Explanation1 ElectricactiverollstabilizationfrontEARSVV(optionalequipment

“ActiveComfortDrive”SA2VS)2 ElectronicPowerSteering(electromechanicalpowersteering)(EPS)3 Wheelaccelerationsensor,frontright(optionalequipment

“ActiveComfortDrive”SA2VS)4 Controlvalvesforshockabsorberadjustment,frontright5 Rideheightsensor,frontright6 Wheelaccelerationsensor,frontleft(optionalequipment

“ActiveComfortDrive”SA2VS)7 Controlvalvesforshockabsorberadjustment,frontleft8 Rideheightsensor,frontleft9 12Vbattery(optionalequipment“ActiveComfortDrive”SA2VS)10 DynamicStabilityControl(DSC)11 BodyDomainController(BDC)12 Stereocamera(optionalequipment“ActiveComfortDrive”SA2VS)13 AdvancedCrashSafetyModule(ACSM-Low)14 Drivingexperienceswitch15 VerticalDynamicsPlatform(VDP)16 Rideheightsensor,rearright17 Controlvalvesforshockabsorberadjustment,rearright


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Index Explanation18 Wheelaccelerationsensor,rearright(optionalequipment

“ActiveComfortDrive”SA2VS)19 Ride-heightsensor,rearleft20 Controlvalvesforshockabsorberadjustment,rearleft21 Wheelaccelerationsensor,rearleft(optionalequipment

“ActiveComfortDrive”SA2VS)22 Electricactiverollstabilizationrear(EARSVH)(optionalequipment

“ActiveComfortDrive”SA2VS)23 PowerControlUnit(PCU)(optionalequipment

“ActiveComfortDrive”SA2VS)

Theoptionalchassisandsuspensionpackage“ActiveComfortDrive”hasthefollowingadditionalcomponents:

• Wheelaccelerationsensorsonall4wheelcarriers• Electricactivestabilizersonthefrontandrearaxles• Anadditional12VbatteryaswellasaDC/DCconverter• Astereocamerainthewindscreen

Wheelaccelerationsensorsareusedintheoptionalchassisandsuspensionpackage“ActiveComfortDrive”forthefollowingreasons:

• Moreprecisedisturbancevariablecontroloftheelectricactivestabilizers(EARSV)possible.Avoidanceofso-calledcopyingfromonewheeltotheotherintheeventofroadbumps.

• PreciseregulationoftheElectronicDamperControl(EDC)ispossiblethroughdetectionofthewheelmovementviathewheelaccelerationsensorsandthebodymovementviatherideheightsensors.ProcessingofthetwoinformationsourcesallowsuseofasimplifiedcontrolunitversionoftheCrashSafetyModule(ACSM-Low).


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6.6.1.Predictivecontrol

Predictivecontroloftheoptionalchassisandsuspensionpackage“ActiveComfortDrive”intheG12

Index Explanation1 Satellite2 Navigationdata3 Stereocamera(KAFAScamera3)4 Controllableshockabsorber,frontleft5 Electricactiverollstabilizationfront(EARSVV)6 Controllableshockabsorber,frontright7 DynamicStabilityControl(DSC)


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Index Explanation8 Controllableshockabsorber,rearright9 VerticalDynamicsPlatform(VDP)controlunit10 Electricactiverollstabilizationrear(EARSVH)11 Controllableshockabsorber,rearleft

Inordertopreparethechassisandsuspensionforthedifferentroadconditionsasearlyaspossible,thefollowingdataisreadinfromvariouscontrolunitsandprocessedtoallowpredictivecontrol:

• IfADAPTIVEdrivingmodehasbeenactivatedviathedrivingexperienceswitch,theDynamicStabilityControlcontrolunitprocessesthenavigationdatatoanalysestherouteandinfluencesthedrivingprogramtobeactivatedifnecessary.Ifthevehicleisapproachingasharpbendathighspeed,forexample,theDynamicStabilityControl(DSC)activatesSportmodewithoutanyactiononthepartofthedriver.TheVerticalDynamicsPlatform(VDP)readsinthisinformationandactivatesthecorrespondingchassiscomponentsforSportmode.Conversely,anautomaticchangeindrivingprogramfromSporttoComfortisalsopossible.Ifthevehicleexitsatwistingsectionofroadthroughwhichithasbeendrivenatspeedandthendrivesatconstantspeedonastraightsection,thisresultsinautomaticchangeovertotheComfortdrivingprogram.Thismeansthattheoptimumdrivingmodewithrespecttocomfort(Comfort)anddrivingdynamics(Sport)isautomaticallysetwithoutmanualoperationofthedrivingexperienceswitchdependingonthedrivingstyleandprobableroute.Routeguidanceneednotbeactivatedforthis.

• TheVerticalDynamicsPlatform(VDP)readsintheinformationofthestereocamerainthewindscreenindependentlyoftheselecteddrivingmodeandprocessesthis.

Inaddition,alargequantityofadditionalinformationsuchasthedrivingstyleanalysisisreadinbytheVerticalDynamicPlatform(VDP)controlunitandusedforpredictivecontrolofthestandardElectronicDamperControl(EDC)aswellastheelectricactivestabilizers(EARSV).

Obstaclescanthereforebeovercomepredictivelyandwithevenmorecomfort.Thedriverisevenlessawareofbumps.Thebodyofthevehicledoesnothavetomoveverticallytothesameextentsincethechassisandsuspensionreactintelligentlyandpredictivelytoroadbumps.

Theoptionalchassisandsuspensionpackage“ActiveComfortDrive”thereforeoffersthefollowingadvantages:

• Reducedcompressionandrebound(EDC).• Reducedpitchmovement(EDC).• Fasterdecayofvehiclebodyreverberations(EDC).• Highdrivingdynamicswhencorneringthankstoactiverollstabilization(EARSV).• Highcomfortforstraight-aheaddrivingduetodecouplingofanti-rollbarhalves

andthusavoidanceofroadbump"copying"(EARSV).

Thefunctionsofthechassisandsuspensionpackage"ActiveComfortDrive”areavailableindifferentformsinthefollowingpositionsofthedrivingexperienceswitch.


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Drivingexperienceswitchposition

ElectricactiverollstabilizationEARSV

ElectronicDamperControl(EDC)

COMFORTPLUS Balanced ComfortableComfort/ECOPRO Balanced BalancedSport Sporty Sporty

Asaresultofintelligentnetworkingofthesystems,failureofonesensorsystem,e.g.thestereocameraduetopoorvisibility,canbesufficientlycompensatedbytheotheravailablesensors.Theridecomfortanddrivingdynamicsthusremainataveryhighlevelunderallconditions.

Thefollowinggraphicshowsaninputandoutputdiagramofthevariouscomponentsforcontroloftheoptionalchassisandsuspensionpackage“ActiveComfortDrive”intheG12.


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Inputandoutputdiagramoftheoptionalchassisandsuspensionpackage“ActiveComfortDrive”intheG12

Index Explanation1 VerticalDynamicsPlatform(VDP)2 Electricactiverollstabilizationfront(EARSVV)3 Electricactiverollstabilizationrear(EARSVH)4 ElectronicDamperControl(EDC)(4x)5 Steeringangle(EPS)6 Navigationdata7 Wheelspeeds(DSC)


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Index Explanation8 Wheelaccelerations9 Rideheights10 Drivingmode11 Roadprofile(stereocamera)12 Lateralandlongitudinalaccelerationandyawrate(ACSM-Low)13 Vehiclespeed

6.6.2.Electricactiverollstabilization(EARSV)Asthefirstvehiclemanufacturerworldwide,BMWuseselectricactivestabilizersinsteadofthepreviouslyusedhydraulicactivestabilizers.Theelectricactivestabilizersintheoptionalequipment“ActiveComfortDrive”(SA2VS)reducetherolltendencyofthebodyinbendsbytargetedapplicationofmechanicalmomentsonthestabilizerhalvesbymeansofanelectricmotor.

Thefollowinggraphicshowsaschematicsystemcomparisonbetweentheactivehydraulicstabilizerandtheactiveelectricstabilizer.


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Schematiccomparisonofhydraulicactivestabilizerandelectricactivestabilizer

Index ExplanationA HydraulicactivestabilizerARS(F01/F02)B ElectricactivestabilizerEARSV(G12)1 Engineoilcooler2 Hydraulicactivestabilizerfront(ARS)3 Expansiontank4 Hydraulicpump5 Valveblock6 VerticalDynamicsManagementcontrolunit(VDM)7 Hydraulicactivestabilizerrear(ARS)8 Electricactiverollstabilizationfront(EARSVV)9 12Vbattery(vehicleelectricalsystemsupport)


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Index Explanation10 Vehicleelectricalsystem11 PowerControlUnitPCU(DC/DCconverter500W)12 VerticalDynamicsPlatform(VDP)controlunit13 Electricactiverollstabilizationrear(EARSVH)

Electrificationoftheactivestabilizeroffersthefollowingadvantages:

• Simpleintegrationin“fullhybrid”drivesystemsActiverollstabilizationispossibleduringpurelyelectricdriving.

• Simpledecouplingofthestabilizerhalvesduringstraight-aheaddrivingImprovedridecomfortduetopreventionofroadbump"copying"

• IncreasedefficiencyEnergyisrequiredexclusivelyduringthecontrolactionsanddoesnotneedtobekeptpermanentlyavailablelikeinahydraulicsystem.Self-aligningforceswhichactontheelectricmotorinthestabilizercanbepartiallyconvertedintoelectriccurrentandfedbackintothevehicleelectricalsystem.

SystemoverviewofelectricactiverollstabilizationEARSV


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Index Explanation1 Electricactiverollstabilizationfront(EARSVV)2 Wheelaccelerationsensor,frontright3 12Vbatteryinenginecompartment(vehicleelectricalsystemsupport)4 Wheelaccelerationsensor,rearright5 VerticalDynamicsPlatform(VDP)6 Rearrightpowerdistributionbox7 PowerControlUnit(PCU)(DC/DCconverter500W)8 Electricactiverollstabilizationrear(EARSVH)9 Wheelaccelerationsensor,rearleft10 Wheelaccelerationsensor,frontleft

Aparticularadvantagewhichcontributesabovealltoincreasingridecomfortisthepreventionofso-called"copying".Whenthevehicleisdrivingstraight-aheadanddrivesoverroadbumps,electricactiverollstabilizationEARSVpermitspracticallyfulldecouplingoftheleftandrightsidestothatcopyvibrationsarealmostexcluded.Theelectricactivestabilizersthereforecompensateforthedisadvantagesofconventionalanti-rollbars.

Thefollowingvariablesaremainlyusedforcalculationoftherequiredactivationoftheelectricactivestabilizers.

• Currentlateralandlongitudinalacceleration• Vehiclespeed• Steeringangle• Wheelacceleration• Rideheights

Theincipientrollmoment(Mw)israpidlycounteractedbyfastprocessingofthedataandactivationofelectricactiverollstabilization(EARSV).


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SectionalviewofanelectricactivestabilizerintheG12

Index Explanation1 Groundconnection2 Electricalconnection3 Controlunit(EARSVV/EARSVH)4 Electricmotor5 Planetarygear(three-stage)6 Decouplingelement7 Anti-rollbarlink8 Torquesensor

TheactivestabilizersreceivethecontrolrequestfromtheVerticalDynamicsPlatform(VDP)controlunit.Thebustelegramsarereadinandprocessedbythecontrolunitsofthetwoactivestabilizers(EARSVV/EARSVH).Thetwostabilizerhalvesaretwistedwithrespecttoeachotherbyactivationoftheelectricmotor.Centralenergyconversiontakesplaceinthepermanentlyexcitedsynchronousmotor,whosedirectionofrotation,torqueandspeedarecontrolledviathesetrotatingfield.

Powertransmissiontakesplaceviathethree-stageplanetarygear,whichconvertsthetorqueoftheelectricmotortotherequiredstabilizeroutputtorsiontorquewitharatioof1:158.Amaximumstabilizertorsiontorqueof750NmiscurrentlyimplementedintheG12.Thesystemisdesignedforsignificantlyhighertorsiontorquesinordertoalsopermitcompensationofsuperpositioneffectsduetoroadbumps.

Theelastomerdecouplingelementbetweentheplanetarygearandstabilizertorsionspringhasthetaskofdecouplinghighlydynamic,low-amplitudeexcitationsfromtheroad.Thisthusmakesafurthercontributiontomeetingthehighcomfortgoals.


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Atorquesensorinsidethecomponentprovidesfeedbackonthecurrentcontroltorquestothecontrolunit.Aplausibilitycheckofthedataallowsvariousfaultstobedetectedandthenstoredintheformofafaultcodeentry.However,repairofthecomponentisnotpossible.Theactiveelectricstabilizermustbereplacedasacompleteunitintheeventofamechanicalcomponentdefect.

Sincetheelectricactivestabilizerwillbeavailableinothervehiclemodelsinfuture,thecontrolunitmustbetaughtfortherespectivevehiclebymeansofversionencodingafterinstallation.Thisensuresthattheelectricactivestabilizerprovidesthecorrectcontroltorquesforthevehicleinquestion.

Technicaldata

Thefollowingtableprovidesanoverviewofthetechnicaldataoftheelectricactivestabilizer.

ElectricactiverollstabilizationEARSV TechnicaldataWeight 14 kg/30lbsMaximumcontrolunittemperature 120 °C/248°FMaximumelectricmotortemperature 160 °C/320°FMaximumelectricmotortorque 7.5Nm/5.5ft-lbsMaximumstabilizertorque 750Nm/553ft-lbsMaximumcurrentconsumption 120AMaximumcurrentoutput -100A

Thevaluesformaximumcurrentconsumptionandmaximumcurrentoutputarethevaluesthatarepossibleforshort-timeoperation.

CurrentconsumptionandcurrentoutputoftheelectricactivestabilizerintheG12


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Theabovegraphicshowsthecurrentconsumptionandoutputoftheelectricactivestabilizerforadrivingmanoeuvrewithapproximately30 %energyrecovery.Itmustbenotedthatthisdiagramisjustasnapshotrepresentation.Dependingonthedrivingmanoeuvre,theactivationpowerandenergyrecoveryoftheelectricactivestabilizermaydifferconsiderably.

FunctiondiagramoftheDC/DCconverterintheG12

Index ExplanationA 12VvehicleelectricalsystemB Consumesofelectricactivestabilizers1 Startermotor2 Alternator3 12 Vbattery4 Consumersofthe12Vvehicleelectricalsystem5 PowerControlUnit(PCU)(DC/DCconverter500W)6 12Vbatteryinenginecompartment(vehicleelectricalsystemsupport)7 Electricactiverollstabilizationfront(EARSVV)8 Electricactiverollstabilizationrear(EARSVH)

Inordertoensurethattheconsumersofthe12VvehicleelectricalsystemintheG12arenotinfluencedbythehighloadcurrentsofthetwoelectricactivestabilizers,thestabilizershavebeenisolatedfromthebasisvehicleelectricalsystembymeansofaDC/DCconverter(500W).

Therequireenergyforactivationisprovidedbyanadditional12Vbatterylocatedintheenginecompartment.Thismeansthatotherconsumersarenotaffectedbythehighenergyconsumption.

Thebatteryisanauxiliarybatterwhichsuppliesthevehicleelectricalsystemwithpowerdependingonthevehicleequipment.Forthisreason,thebatterymayalsobepresentevenifthevehicleisnotequippedwithelectricactivestabilizers.


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6.6.3.ControlstrategyVehicledrivabilitywhencorneringcanbegreatlyinfluencedbyanti-rollbarsonthefrontandrearaxles.Adecisivefactorhereistherollmomentratiobetweenthefrontandrearvehicleaxles.Thisratiodependsontherespectiveanti-rollbarmomentsofthetwoaxles.

Thefollowingtableprovidesanoverviewofthepossiblerollmomentratiosandtheresultanthandlingofthevehicle.

Anti-rollbar Rollmomentratio Understeer OversteerFrontaxlesoft/rearaxlehard

<50% X

Frontaxlehard/rearaxlesoft

>50% X

Thefollowinggraphicshowsthepercentagedistributionofthestabilizermoments(rollmomentratio)oftheactivestabilizersonthetwovehicleaxles.

Characteristiccurveofactivestabilizeronfrontandrearaxles

Index ExplanationA UndersteeringrollmomentratioB NeutralrollmomentratioMain[%] Momentdistributionofactivestabilizersinpercentvin[km/h] Drivingspeedinkilometersperhour1 Activestabilizeronthefrontaxle2 Activestabilizerontherearaxle


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Theactivestabilizerallowstherollmomentratiotobeadaptedtotherespectivedrivingsituationinordertoincreasethedrivingdynamics.Therollmomentratiois50 : 50(neutral)inthelowerspeedrange(0 ~ 50km/h).Therollmomentratioisadjustedtowardsundersteerwithincreasingspeed.

Applicationofrollmomentsviatheactivestabilizerinfluencesthecorneringforcesthatcanbetransferredbythetires.

Thefollowinggraphicshowsthemaximumcorneringforcesthatcanbetransferredwhencorneringasafunctionoftheappliedstabilizermoments.

Diagramofapositiverollmomentratiothroughcontrolvia2activestabilizers

Index ExplanationA LargemomentoftheactivestabilizeronthefrontaxleB LowmomentoftheactivestabilizerontherearaxleC IncreaseintransferablecorneringforceatthewheelD ReductionintransferablecorneringforceatthewheelE ResultanttransferablecorneringforceatthewheelsofanaxleFS TransferablecorneringforceatthewheelFN VerticalwheelforceHL Forceofactivestabilizeratrearleftwheel


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Index ExplanationHR ForceofactivestabilizeratrearrightwheelMa ActivestabilizermomentVL ForceofactivestabilizeratfrontleftwheelVR Forceofactivestabilizeratfrontrightwheel

Whencornering,acounter-torque(Ma)isappliedbytheactivestabilizerstocounteracttheactingrollmoment(Mw).Themoments(Ma)applieddependingontheactionoftheactivestabilizerseitherincreaseorreducethetirecontactforcesofthedifferentwheels.

Ifawheelisloadedwithaparticularlyhighforcebytheactivestabilizer,itstransferablecorneringforceincreasesduetothehighertirecontactforce.Incontrast,theloadontheoppositewheelisrelieved,anditscorneringforceisthusreducedduetothelowertirecontactforce.Theresultanttirecontactforcescharacterisethetransferablecorneringforcesofthewheelsonanaxle.

Sincethereductioninthetransferablecorneringforcesoftherelievedwheelisproportionatelyhigherthantheincreaseinthetransferablecorneringforcesoftheloadedwheelasaresultofincreasingactivestabilizerforce,thismeansthatthereisareductionintheresultantcorneringforceofthewheelsonthisaxle.

Inthedirectcomparisonofthetwoaxlesintheabovediagram,itcanbeseenthattherearaxlecantransferahigherresultanttransferablecorneringforcethanthefrontaxle.Inthelimitrange,thevehiclewouldthereforepushoverthefrontwheels,i.e.understeer.

Itiseasierforaninexperienceddrivertoregaincontroloverthevehicleagaininthissituationthanifthevehicleweretooversteer(vehicleskidsattherearaxle).


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6.6.4.SystemwiringdiagramofelectricactiverollstabilizationEARSV

SystemwiringdiagramofelectricactiverollstabilizationEARSVintheG12


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Index Explanation1 Wheelaccelerationsensor,frontleft2 Electricactiverollstabilizationfront(EARSVV)3 Powerdistributionbox,enginecompartment4 Wheelaccelerationsensor,frontright5 12Vbatteryinenginecompartment(vehicleelectricalsystemsupport)6 BodyDomainController(BDC)7 Powerdistributionbox,frontright8 VerticalDynamicsPlatform(VDP)9 Wheelaccelerationsensor,rearright10 Rearrightpowerdistributionbox11 Electricactiverollstabilizationrear(EARSVH)12 Wheelaccelerationsensor,rearleft13 KAFAScameracontrolunit14 Stereocamera

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