Relieving Hydraulic System Pressure - Toro 30821 Service Manual

Relieving Hydraulic System Pressure

Before disconnecting or performing any work on the
Groundsmaster 3500- D hydraulic system, all pressure
in the hydraulic system must be relieved. Park machine
on a level surface with the cutting units lowered and off.
Turn key switch to OFF and allow engine to stop.
To relieve hydraulic pressure in traction circuit, move
traction lever to both forward and reverse directions. To
relieve hydraulic pressure in steering and lift circuits, ro-
tate steering wheel in both directions.
To relieve cutting unit system pressure, turn key switch
to ON (engine not running). Move PTO switch to engage
Traction Circuit (Closed Loop) Component Failure
The Groundsmaster 3500- D traction circuit is a closed
loop system that includes the hydrostat and two (2)
wheel motors. If a component in the traction circuit
should fail, debris and contamination from the failed
component will circulate throughout the traction circuit.
This contamination can damage other components in
the circuit so it must be removed to prevent additional
component failure.
If a component failure occurs in the traction circuit, it is
critical that the entire traction circuit be disassembled,
drained and thoroughly cleaned to ensure that all con-
tamination is removed from the circuit. If any debris re-
mains in the traction circuit and the machine is operated,
the debris can cause additional component failure.
An additional step for removing all traction circuit con-
tamination would be to temporarily install a high pres-
sure hydraulic oil filter (see Special Tools) into the circuit.
The filter could be used when connecting hydraulic test
gauges in order to test traction circuit components or af-
ter replacing a failed traction circuit component (e.g. hy-
drostat or wheel motor). The filter will ensure that
contaminates are removed from the closed loop and
thus, do not cause additional component damage.
Hydraulic System (Rev. G)
which will energize the solenoid valve on hydraulic man-
ifold to relieve circuit pressure. Move PTO switch to dis-
engage, return key switch to OFF and remove key from
the ignition switch.
NOTE: Moving steering wheel with engine off may un-
seat implement relief valve. If steering or lift circuits ap-
pear weak or inoperative after machine is returned to
service, repeat relieving hydraulic system pressure pro-
cedure.
Once the filter has been placed in the traction circuit,
place the machine on jack stands and operate the trac-
tion circuit to allow oil flow through the circuit. With the
machine raised off the ground, the traction circuit will
have maximum oil flow at minimum pressure to mini-
mize damage from any remaining contamination. The
filter will remove contamination from the closed loop
traction circuit during operation. Remove the filter from
the machine after contamination has been removed
from the traction circuit.
IMPORTANT: When operating the traction system with
the high pressure filter installed, make sure that flow is
always directed through the filter (e.g. do not press the
traction pedal in the reverse direction if the filter is placed
for forward direction flow). If flow is reversed, debris
from the filter will re- enter the traction circuit.
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