Service Manual

Rev. C
Reelmaster 5200-D/5400-D Hydraulic SystemPage 4 - 11
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 in the for-
ward direction. Operating 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, pressure can increase to a maximum of
3625 PSI in the forward direction.
Pushing the bottom of the traction pedal rotates the vari-
able displacement pump swash plate to create a flow of
oil. This oil is directed to the fixed displacement motor
which turns the differential input shaft to drive the front
wheels in a reverse direction. Operating 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, pressure can increase to
a maximum of 2755 PSI in the reverse direction.
Main system 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 transmis-
sion. If pressure exceeds the relief setting, oil flows
through the 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.
Hydraulic
Systems