user manual

Groundsmaster 4100--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-
draulicflowtothesteeringcontrolvalveandthelift/lower
controlvalve.Pumphydraulicflowisdeliveredtothetwo
circuitsthroughaproportionalflowdividerlocatedinthe
fandrivemanifold.Thegearpumptakesitssuctionfrom
thehydraulicreservoir.Steering circuitpressureislimit-
ed to 1350 PSI (93 bar) by a relief valve located in the
steering control.
With the steering wheel in the neutral position and the
enginerunning, flowenters thesteeringcontrol valveat
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
thesteeringcontrol valve atthe Pport goesthrough the
spool andis routed totwo places. First,most of theflow
through the valve is by--passed out the PB port back to
the oil filter and traction charge circuit. Second, the re-
mainder of the flow is drawn through the rotary meter
(V1) and out the Lport. Pressure contracts the steering
cylinder piston for a left turn. The rotary meter ensures
that the o il flow to the cylinder is proportional to the
amount of the turningonthe steering wheel. Fluid leav-
ingthe cylinder flowsback throughthe spool valvethen
through the T port and to the hydraulic reservoir.
Thesteeringcontrolvalvereturnstotheneutralposition
when turning is completed.
Right Turn
When a right turn is made with the engine running, the
turningofthesteeringwheelpositionsthespoolvalveso
thatflow goesthrough thebottomof thespool. Flowen-
tering the steering control valve at the P port goes
throughthespoolandisroutedtotwoplaces.Asinaleft
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 .
Pressureextends the steeringcylinder pistonfor a right
turn.Therotarymeterensuresthattheoilflowtothec yl-
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.
Thesteeringcontrolvalvereturnstotheneutralposition
when turning is completed.
Figure 13
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
STEERING CYLINDER
Hydraulic
System