Case IH PUMA 145 - Page 43

HYDRAULIC,PNEUMATIC,ELECTRICAL,ELECTRONICSYSTEMS-PRIMARYHYDRAULICPOWERSYSTEM
BAIL07APH326ASA20
Operationoftheclosedcentrehighpressurehydrauliccircuitisasfollows:-
Thecomponentsinthehighpressurehydrauliccircuitareconnectedbytheirloadsensinglinestothehydraulicload
sensingvalvewhichcontrolstheoutputofthehydraulicpump.
Whenthetrailerbrakes,remotecontrolvalves,hydraulicliftorfrontaxlesuspension(wheretted)areoperating,the
loadsensingvalveonvariableowpistonpump,comparesthepressureinthecomponentloadsenselinewiththe
outputpressureofthehydraulicpump.
Ifpumpoutputpressureislessthanthecombinedpressureoftheloadsenselineandspringforceoftheowcon-
trolvalve,thenpumpoutputcontinuestoincrease.Whencircuitdemandissatisedpumppressureovercomesthe
combinedpressureoftheloadsenselineandowcompensatingvalvespring.Thismovesthespoolintheowcom-
pensatingvalvetotheright,allowingcontrolpressureoiltobedirectedtothevariableowswashplateservopiston,
whichde-strokesthepumptoadjustoutputtocircuitdemand.
HighPressureoilisfedtoasubplateatthebottomoftheremotevalvestackwhereitisdirectedtotheTrailerBrake
valvewhichhaspriorityforsafetyreasons.TheoilisthenredirectedtotheElectronicDraftControlValveandthe
Electro-HydraulicRemoteValves.Withinthesubplateisapressurecompensatingvalvewhichdivertstheoiltothe
lowpressuresystematapressureof18bar(261.00psi).
HighPressureoilisalsofedtothetopoftheRemoteValvestackthroughanendplatewhichincorporatesapressure
limitingvalveandthissuppliesoilat20-22bartothepilotlinegalleriesintheElectro-HydraulicRemoteValves.
Surplusoilfromthechargepumptothevariabledisplacementpumpisfedpastthe0.8barvalveandbooststhe
pressureinthelubricationcircuit.
Thetrailerbrakevalveislocatedonthesubplateoftheremotevalvestack.Thevalvedivertsoilpressuretothe
trailerbrakeswheneverthebrakepedalsaredepressed.
Thetrailerbrakehasabsolutepriorityoverotherservicesinthecircuit.
BAIL07APH327ASA21
Theremotevalvesareavailableastwo,threeorfourvalvespertractor.
Thevalvescanbedouble-actingwithoatandkickout.
Doubleactingconvertibletosingle-actingwithoat.
84479138A06/06/2011
A.10.A/15