Groundsmaster 4100 --D/4110--D Hydraulic SystemPage 4 -- 23
Steering Circuit
A four section gear pump is coupled to the piston (trac-
tion) pump. The third gear pump section supplies hy-
draulic flow to both the steering and lift/lower circuits.
Hydraulicflow from this pumpsectionisdelivered to the
two circuits througha proportionalflow divider that is lo-
cated in the fan drive manifold. This flow divider splits
pump flow approximately 50% for the steering circuit
and 50% for the lift/lower circuit.
Steering circuit pressure is limited to 1350 PSI (93 bar)
byareliefvalvelocatedinthesteeringcontrolvalve.Cir-
cuit pressure can be m easured at a test port in the hy-
draulic supply tube.
With the steering wheel in the neutral position and the
engine running, flow enters the steering control valve at
the P port and goes through the steering control spool
valve, by--passing the rotary meter (V1) and steering
cylinder. Flow leaves the control valve through the PB
port to the oil filter and traction charge circuit.
Left Turn
When a left turn is made with the engine running, the
turningofthesteeringwheelpositionsthespoolvalveso
thatflowgoesthroughthetopofthespool.Flowentering
the steering controlvalve at the P port goes through the
spool and is routed to two places. First, most of the flow
throughthevalveisby--passedoutthePBportbackto
the oil filter and traction charge circuit. Second, the re-
mainder of the flow is drawn through the rotary meter
(V1) and out the L p ort. Pressure contracts the steering
cylinder piston for a left turn. The rotary meter ensures
that the oil flow to the cylinder is proportional to the
amount of the turning on the steering wheel. Fluid leav-
ing the cylinder flows back throughthe spool valve then
through the T port and to the hydraulic reservoir.
Thesteeringcontrol valvereturns totheneutralposition
when turning is completed.
Right Turn
When a right turn is made with the engine running, the
turningofthesteeringwheelpositionsthespoolvalveso
that flow goes throughthebottom ofthe spool.Flowen-
tering the steering control valve at the P port goes
throughthespoolandisroutedtotwoplaces.Asin aleft
turn,mostoftheflowthroughthevalveisby--passedout
the PB port back to the oil filter and traction charge cir-
cuit. Also like a left turn, the remainder of the flow is
drawn through rotary meter (V1) but goes out port R.
Pressure extends the steering cylinder piston for a right
turn.Therotarymeterensuresthattheoilflowtothecyl-
inder is proportional to the amount of the turning on the
steering wheel. Fluid leaving the cylinder flows back
through the spool valve then through the T port and to
the hydraulic reservoir.
Thesteeringcontrol valvereturns totheneutralposition
when turning is completed.
Figure 14
1350
PSI
PB
STEERING
T
R
P
L
PISTON MOVEMENT
CONTROL
1350
PSI
PB
STEERING CYLINDER
STEERING
T
R
P
L
PISTON MOVEMENT
CONTROL
1350
PSI
PB
STEERING CYLINDER
STEERING
T
R
P
L
CONTROL
LEFT TURN
NEUTRAL POSITION
RIGHT TURN
NO PISTON MOVEMENT
STEERINGCYLINDER
Hydraulic
System
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