Steering Circuit (Machine Serial Number Below 316000000) - Toro Groundsmaster 3280-D Service Manual

Steering Circuit (Machine Serial Number below 316000000)

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Left Turn
Groundsmaster ® 3280-D/3320
05138SL Rev B
The charge pump in the transmission supplies flow for the steering circuit and
for the lift circuit. Charge pump output flows to the steering control valve before
reaching the lift valve so that the steering circuit has priority. Steering circuit
pressure is limited to 5,515 kPa (800 psi) by the implement relief valve located in
the transmission.
When the steering wheel is not being turned and the engine is running
(transmission input shaft being rotated), charge pump flow enters the steering
control valve at the P port and by-passes the rotary meter and steering cylinder.
Flow leaves the steering control valve through the E port and is directed to the
lift control valve.
When a left turn is made with the engine running, the turning of the steering
wheel positions the steering control spool valve so that flow goes through the
bottom 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 fluid flow to the
cylinder is proportional 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 hydraulic reservoir (front axle).
Figure 56
Page 5–35 Hydraulic System: Hydraulic Flow Diagrams