Steering Circuit - Toro Groundsmaster 4100-D Service Manual

Steering Circuit

A three section gear pump is coupled to the piston (trac-
tion) pump. The gear pump section farthest from the pis-
ton pump supplies hydraulic flow to the steering control
valve and the lift/lower control valve. Pump hydraulic
flow is delivered to the two circuits through a proportion-
al flow divider. The gear pump takes its suction from the
hydraulic reservoir. Steering circuit pressure is limited
by a relief valve located in the steering control valve.
With the steering wheel in the neutral position (rear
wheels positioned straight ahead) and the engine run-
ning, 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
turning of the steering wheel positions the spool valve so
that flow goes through the top of the spool. Flow entering
the steering control valve at the P port passes through
the rotary meter (V1) and is directed out the L port. Pres-
sure contracts the piston for a left turn. The rotary meter
STEERING CYLINDER
NO PISTON MOVEMENT
L
R
1350
PSI
T
PB P
STEERING
CONTROL
NEUTRAL POSITION
Groundsmaster 4100--D
ensures that the oil flow to the cylinder 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.
The steering wheel and steering control valve return to
the neutral position when turning is completed.
Right Turn
When a right turn is made with the engine running, the
turning of the steering wheel positions the spool valve so
that flow goes through the bottom of the spool. Flow en-
tering the steering control valve at the P port passes
through rotary meter (V1) is directed out port R. Pres-
sure extends the piston for a right 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
leaving the cylinder flows back through the spool valve
then through the T port and to the hydraulic reservoir.
The steering wheel and steering control valve return to
the neutral position when turning is completed.
STEERING CYLINDER
PISTON MOVEMENT
L
R
1350
PSI
T
PB P
STEERING
CONTROL
LEFT TURN
Figure 12
Page 4 - - 17
STEERING CYLINDER
PISTON MOVEMENT
L
R
1350
PSI
T
PB P
STEERING
CONTROL
RIGHT TURN
Hydraulic System