Toro Sand Pro 3040 Service Manual page 87

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Right Turn
Left Turn
Sand Pro ® 3040 and 5040
20251SL Rev A
The implement/charge pump (P2) is a fixed displacement gerotor pump that
is part of the traction pump. The implement/charge pump supplies oil flow for
the steering circuit on model 08745 machines. The implement/charge pump
also supplies fluid flow for the lift circuit and the charge circuit of the closed
loop traction system for both model 08743 and 08745 machines. The pump
output flows to the steering control valve before supplying the lift and charge
circuit needs so that the steering circuit has priority. The steering and lift circuit
pressure is limited to 5,171 kPa (750 psi) by a relief valve located in the steering
valve. The steering valve also includes two 10,342 kPa (1500 psi) relief valves,
one for each cylinder supply port L and R. The relief valves absorb shocks in the
steering circuit while turning into and over a curb for example.
When the steering wheel is not being turned and the engine is running (hydraulic
pump input shaft rotating), implement/charge pump flow enters the steering
valve at the P port and by-passes the rotary meter and steering cylinder. Flow
leaves the steering valve through the E port and is directed to the lift valve to
supply the lift and charge circuits.
When a right turn is made with the engine running, turning 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 R port. Pressure 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 rotation of the steering wheel. Fluid leaving
the steering cylinder flows back through the spool valve, then out the T port of
the steering valve and returns to the hydraulic tank. When the steering wheel
reaches the end of its rotation, the relief valve in the steering valve opens and
directs the hydraulic flow out the steering valve T port to the oil cooler until the
steering wheel is released.
When a left turn is made with the engine running, turning the steering wheel
positions the steering control spool valve so that flow goes through the top of
the spool. Flow entering the steering control valve at the P port passes through
Figure 26
Page 5–17 Hydraulic System: Hydraulic Flow Diagrams