Toro Groundsmaster 328-D, Service Manual

Page: 223 / 402

Power Steering Schematics
When the steering wheel is turned to the right (Fig. 3),
the control valve within the steering valve shifts to close
the “AUX” port. This directs oil supplied by the steering
pump to the metering section of the steering valve. As
the steering wheel is turned, system oil is metered out
port “RT” to the steering cylinder. Oil displaced by the
other end of the steering cylinder returns to the steering
valve through port “LT” and is directed out port “OUT”
back to reservoir.
NOTE: On 2WD units right turn pressure is supplied
to the rod end of the steering cylinder and left turn
pressure to the barrel end as shown. On 4WD units
these hydraulic lines are reversed (right turn pres­
sure to barrel end and left turn pressure to rod end).
When the steering wheel is stationary, the control valve
within the steering valve shifts back to neutral (Fig. 4),
allowing system oil to flow through the steering valve
and out the “AUX” port back to reservoir. Oil in the rest
of the steering circuit is then trapped.
Right Turn
STEERING CYLINDER
STEERING VALVE
FROM
PUMP
Figure 3
Neutral
STEERING CYLINDER
STEERING VALVE
FROM
PUMP
Figure 4
When the steering valve is turned to the left (Fig. 5) oil
is metered out port “LT” to the steering cylinder. Oil
displaced by the other end of the cylinder returns to the
steering valve through port “RT” and is directed out port
“OUT” back to reservoir.
Left Turn
STEERING CYLINDER
STEERING VALVE
FROM
PUMP
Figure 5
Groundsmaster
®
300 Series Page 8 - 3 Power Steering Schematics