Hydraulic Flow Diagrams Page 4 - 8 Groundsmaster
®
455-D
Return
Pressure
Oil
Aux.
Pump
Suction
Reservoir
Traction
Motor
Filter
Cooler
Traction
Motor
ENGINE
Traction
Pump
When the top of the traction pedal is pushed down, a variable displacement hydrostatic
Traction Circuit – Forward
Flow
piston pump creates a flow of oil to a fixed displacement piston motor mounted on the
two-speed axle to drive the machine forward. On
two wheel drive
units, this flow returns
to the traction pump and continues to operate in a closed loop.
Four wheel drive
units
have another piston motor connected in series with the front motor and mounted to the
steerable rear axle. On these units, flow is from the pump to the front motor, through a
solenoid valve, then to the rear motor and back to the pump, continuing in a closed loop.
An interlock switch on the front axle controls the 4wd solenoid valve to engage four
wheel drive only when the transmission is in low gear. When in four wheel drive, an
over-running clutch between the motor and rear axle automatically engages the rear
axle only when the front wheels begin to slip.
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