Service Manual

Mid-Size Walk Behind Service Manual 5 - 1
HYDRAULIC DRIVE SYSTEMS
Hydraulic Drive System Overview
The hydrostatic drive system consists of two bi-
directional high-pressure loops, one for each drive
wheel. Each loop is made up of a pump, motor, and the
high-pressure hoses connecting them together. Both
high-pressure loops share a common low-pressure
supply system. The components of the low-pressure
supply system are the reservoir, filter, and low-
pressure hoses.
The pump is driven by an internal combustion engine
through a belt and pulley system.
The speed and direction of each drive wheel is
controlled independently by varying the output of the
pump. The output of the pump is varied by moving the
speed control handle and drive lever.
The charge pump portion of the pump circulates fluid
through the low-pressure system.
Oil is drawn through each pump’s case drain line to the
reservoir for cooling, then through the filter for cleaning
and finally pumped back into the high pressure loop by
the charge pump.
On fixed deck models only, a cold start ring is used,
which when engaged, removes tension from the pump
drive belt. This reduces the effort required to pull the
recoil starter when in cold temperatures.
More detailed information about each component can
be found on the Toro Hydraulic Troubleshooting CD
(PN# 492-4777), Ross Wheel Motor Service and
Repair Manual (492-4753), and the Hydro-Gear
Service and Repair Manual, PN# 492-4749.
Hydraulic System