Traction Circuit - Toro Reelmaster 6500-D Service Manual

Traction Circuit

The hydraulic pump assembly is driven by a coupling at-
tached to the engine flywheel. The pump assembly con-
sists of a three section gear pump, a gerotor charge
pump, and a variable displacement piston pump.
Pushing the top of the traction pedal engages a hydrau-
lic servo valve which controls the variable displacement
piston pump swash plate to create a flow of oil. This oil
is directed to two fixed displacement motors. Each mo-
tor powers a planetary drive assembly located behind
each of the front wheels. On 4WD units the hydraulic oil
continues on to a fixed displacement motor and gearbox
assembly attached to the rear axle.
Operating pressure on the high pressure side of the
closed drive circuit is determined by the amount of load
Reelmaster 6500-D/6700-D
developed at the fixed displacement motors. As the load
increases, pressure can increase to a maximum of 4000
PSI (276.0 bar). Main system pressure is limited by a
high pressure relief valve on each side of the closed
drive circuit. If pressure exceeds the relief setting, oil
flows through the relief valve to the low pressure side of
the closed drive circuit.
A gerotor charge pump provides a constant supply of oil
to the variable displacement pump and closed drive cir-
cuit for lubrication and to make up for oil that is lost due
to internal leakage in the pump and motors. Charge
pressure is limited to 250 PSI (17.2 bar) by a relief valve
(R5).
Page 4 - 15 Rev. C Hydraulic System