Right And Left Turn - Toro Greensmaster 3150 Service Manual

Right and Left Turn

The gear pump (P2) is directly coupled to the hydrostat
through gear pump (P1). It supplies hydraulic pressure
to the power steering valve for turning the rear wheel, for
raising and lowering the cutting units, and for maintain-
ing 100 to 150 PSI (6.9 to 10.0 Bar) to the low pressure
side of the traction circuit (charge pressure). The gear
pump (P2) takes its suction from the hydraulic reservoir.
Maximum circuit pressure is limited by relief valve (R5).
With the steering wheel in the neutral position (rear
wheel positioned straight ahead) and the engine run-
ning, the spool valve is in the center position. Flow en-
ters the steering control valve at Port (P) and goes
through the spool valve, by–passing the steering cylin-
der. Flow leaves the control valve out port (E) and con-
tinues through solenoid valve (S2) to the hydrostat.
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 top of the spool. Flow entering
the steering control valve at Port (P) goes through the
spool and is routed to two places. First, most of the flow
through the valve is by–passed out port (E) back
through solenoid valve (S2) to the hydrostat. Second,
the remainder of the flow is drawn through the rotary me-
ter (V1) and out port (R). Pressure moves the piston in
the direction for a right turn. The rotary meter ensures
that the oil flow to the cylinder is proportional to the
Hydraulic System
amount of the turning on the steering wheel. Fluid leav-
ing the cylinder flows back through the spool valve and
out port (T). The returning flow passes through the man-
ifold block (using ports ST and PT) and on to the hydros-
tat.
The steering wheel and steering control valve return to
the neutral position when turning is complete.
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 bottom of the spool. Flow en-
tering the steering control valve at Port (P) goes through
the spool and is routed to two places. First, most of the
flow through the valve is by–passed out port (E) back
through solenoid valve (S2) to the hydrostat. Second,
the remainder of the flow is drawn through rotary meter
(V1) and out port (L). Pressure moves the piston in the
direction 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 leaving the cylinder
flows back through the spool valve and out port (T). The
returning flow passes through the manifold block (using
ports ST and PT) and on to the hydrostat.
The steering wheel and steering control valve return to
the neutral position when turning is complete.
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