Traction Circuit - Toro Reelmaster 5200-D Service Manual

Traction Circuit

The hydrostatic transmission is driven by a drive shaft
off the front of the engine crankshaft. Pushing the top of
the traction pedal, rotates the variable displacement
pump swash plate to create a flow of oil. This oil is di-
rected to the fixed displacement motor which turns the
differential input shaft to drive the front wheels. Operat-
ing pressure on the high pressure side of the closed loop
is determined by the amount of load developed at the
fixed displacement motor. As the load increases, pres-
sure can increase to a maximum of 3625 PSI. Main sys-
tem pressure is limited by a high pressure relief valve on
each side of the closed loop circuit. System pressure
can be measured at test ports on the transmission. If
pressure exceeds the relief setting, oil flows through the
Reelmaster 5200-D/5400-D
relief valve to the low pressure side of the closed loop
circuit.
An integral charge pump provides a constant supply of
charge oil to the variable displacement pump and closed
loop circuit for lubrication and to make up for oil that is
lost due to internal leakage in the pump and motor.
Charge pump flow is directed through the oil cooler, then
through the filter to the low pressure side of the closed
loop circuit. A cooler bypass valve and filter bypass
valve allow charge oil flow to the closed loop if the cooler
or filter becomes plugged. Charge pressure is limited to
150 PSI by a relief valve. Charge pressure can be moni-
tored at the charge pump test port.
Page 4 - 11 Hydraulic System