Case IH PUMA 145 - Page 38

HYDRAULIC,PNEUMATIC,ELECTRICAL,ELECTRONICSYSTEMS-PRIMARYHYDRAULICPOWERSYSTEM
BSE3845A9
1.PowerBeyondPorts
2.PressureReliefValve
NOTE:SemiPowershifttransmissiontractorshavetwoshiftbuttonsplusanextrarangebuttononthereverseside
ofthehandle.
CLOSEDCENTRELOADSENSINGHIGHPRESSUREHYDRAULICCIRCUIT
Theprincipalofoperationoftheclosedcentreloadsensinghighpressurehydrauliccircuitwithvariableowpiston
pumpistosupplyoilowondemand.Italsoenablessimultaneousoperationofthetrailerbrakes,hydrauliclift,
remotecontrolvalveassembliesandfrontaxlesuspensionwheretted.Theloadsensingvariableowpistonpump
offerssignicantbenetsinreducingtheenginepowerlossthatoccursinopencentresystemswhereahighvolume
ofoil,oftenfarinexcessofdemand,iscontinuouslypumpedroundthehydrauliccircuitevenwhentheyarenotbeing
operated.
Axeddisplacementpump(ChargePump)servesasaninitialdisplacementpumpforthevariabledisplacementpump
.Thevariabledisplacementpumprstofallsuppliesoiltothetrailerbrakevalve(wheretted),theremotevalves
andelectronicdraftcontrolvalveandapilotoilsupplywithlowerpriority.Thehighestloadpressureisindicatedto
theowandcompensatingvalveonthepumpviatheloadsensingline.Theowandcompensatorvalvecontrols
thepumppressureinsuchawaythatitalwaysexceedsthehighestloadpressurebyapre-setdifference.Apriority
valveforlowpressurecircuitdemandislocatedinthebottomsubplateoftheremotevalvestack.Tractorsttedwith
Electro-hydraulicremotevalvesalsohavehighpressureoilsuppliedfromthevariabledisplacementpumptothetop
plateoftheremotevalvestack.Theoilpassesthroughthetopplateviaasmalllterandapressurelimitingvalve(
20-22Bar).Theoilisthendirectedtothepilotoilsupplyoftheelectro-hydrauliccontrolvalve.
84479138A06/06/2011
A.10.A/10