Groundsmaster 4300--D Hydraulic SystemPage 4 -- 21
Steering Circuit
A four section gear pump is coupled to the piston (trac-
tion) pump. Gear pump section P3 supplies hydraulic
flow to the steering control valve and for the traction
chargecircuit. Thegearpump takesitssuction fromthe
hydraulicreservoir.Steeringcircuitpressureislimitedto
1000 PSI (70 bar) by a relief valve (R10) located in the
steering control valve.
With the steering wheel in the neutral position and the
engine running, hydraulic flow enters the steering con-
trol valve at the P port and goes through the steering
controlspoolvalve,bypassingtherotarymeter(V1)and
steering cylinder. Flow leaves thecontrol valve through
theTporttothetransmissionoilfilterandtractioncharge
circuit.
Left Turn (Fig. 20)
When a left turn is made with the engine running, the
turningof thesteeringwheel positionsthe steeringc on-
trol spool valve so that flow is directed through the bot-
tomofthespool.Flowenteringthesteeringcontrolvalve
attheP portgoesthroughthe spoolandis routedtotwo
places. First, most of the flow through the v alve is by-
passed out the T port back to the transmission oil filter
andtractionchargecircuit.Second,theremainderofthe
flowisdirectedthroughtherotarymeter(V1)andoutthe
L port. Pressure contracts the steering cylinder piston
for a left turn. The rotary meter ensures that the oil flow
to the steering cylinder is proportional to the amount of
turningon thesteering wheel.Fluid leavingthesteering
cylinder flows back through the steering control spool
valve and then out of the steering control valve through
the T port.
Thesteeringcontrolvalvereturnstotheneutralposition
when turning is completed.
Right Turn (Fig. 20)
When a right turn is made with the engine running, the
turningof thesteeringwheel positionsthe steeringc on-
trol spool valve so that flow is directed through the top
of the spool. Flow entering the steering c ontrol valve at
the P port goes through the spool and is routed to two
places. As in a left turn, most of the flow through the
valveisbypassedouttheTportbacktothetransmission
oil filter and traction charge circuit. Also like a left turn,
the remainder of the flow is directed through rotary me-
ter(V1)butgoesoutportR .Pressureextendsthesteer-
ing cylinder piston for a right turn. The rotary meter
ensures that the oil flow to the steering cylinder is pro-
portional to the amount of the turning on the steering
wheel. Fluid leaving the steering cylinder flows back
through the steering control spool valve then through
the T port and to the hydraulic reservoir.
Thesteeringcontrolvalvereturnstotheneutralposition
when turning is completed.
Hydraulic
System
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