Steering Circuit - Toro Workman HDX Auto Service Manual

Steering Circuit

The hydraulic gear pump supplies flow for the steering
circuit and for raising and lowering the bed. Pump output
flows to the steering control valve before reaching the lift
valve so the steering circuit has priority. Circuit pressure
is limited by a relief valve located in the steering control
valve.
NOTE: On vehicles with High Flow Hydraulics, a two (2)
section gear pump is used. The front gear pump section
supplies oil for steering and raising/lowering the bed.
The rear pump section on these vehicles provides sys-
tem flow for accessories.
When the steering wheel is not being turned with the en-
gine running (hydraulic pump being rotated), flow enters
the steering control valve at the P port and by−passes
the rotary meter and steering cylinder. Flow leaves the
control valve through the E port and is directed to the lift
valve.
Left Turn (Fig. 9)
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 and is directed out the L port. Pressure
retracts the steering cylinder for a left turn. The rotary
meter ensures that the oil flow to the cylinder is propor-
tional to the amount of the turning on the steering wheel.
Fluid leaving the steering cylinder flows back through
the spool valve, then out the T port and returns to the hy-
draulic reservoir.
The steering control valve returns to the neutral position
when turning is completed.
Workman HDX Auto
Right Turn (Fig. 9)
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 the rotary meter and is directed out port R. Pres-
sure extends the steering cylinder 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 out the T port and to the hydraulic
reservoir.
The steering control valve returns to the neutral position
when turning is completed.
Page 7 − 11 Hydraulic System