WABCO TAILGUARD - Separate Valves for Vehicles with an ABS Braking System

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5.2.1 Separate valves for vehicles with an ABS braking system
Whenthedriveractuatesthebrakingvalve(2)onatowingvehicleequippedwithanABSbrakingsystem,thebraking
pressurefortherearaxlereachesthecontrolinputoftheLSVregulator(9),whichthenadaptsthebrakingpressure
totheloadstatusofthevehicle.ItsoutputpressurereachestheTristopcylindersattherearaxleviathetwoABS
solenoidvalves(10).
Toadditionallyenableautonomousbrakingactions,thestandardcongurationofthispartoftheABSbrakingsystem
isextendedwithTailGUARD™asfollows:
 Supplypressurefortherearaxleispassedonviaabranchlinetoanappropriatelysetchargingvalve(3).The
effectofthisisthatautonomousbrakingisonlypossibleatasufcientsupplypressureofatleast7.3bar.
 Fromhere,thepressurereachesapressurelimitingvalve(4).Thismakesitpossibletosetthemaximumbraking
pressurethatcanbegeneratedforanautonomousbrakingaction.Inthecaseofrefusecollectionvehicles,a
maximumbrakingpressureofapprox.3.8barhasfrequentlyprovedtobemosteffective.
 Thebrakingpressurethenpassesthroughtwosolenoidvalves(5)and(6)thatareconnectedinseries.Theseare
controlledbytheECU(1),andenablemodulationofabrakingpressurethatisadaptedtothevehiclespeed.The
seriescircuitensuresthatthevehicleisonlybrakedwhenbothvalvesareactuated.Thispreventsanautonomous
brakingactionfrombeingtriggeredduetoanelectricalfault.
 ThemodulatedbrakingpressureisfedintothecontrolinputoftheLSVregulator(9)viaatwo-wayvalve(7).From
here,theoutputpressurereachestheTristopcylindersoftherearaxleintheusualmanner.Thebrakingpressure
isalsomeasuredbyapressuresensor(8)thatislikewiseconnectedtotheECU(1).
Required components: Overview