Relieving Hydraulic System Pressure; Traction Circuit Component Failure - Toro Groundsmaster 4000-D Service Manual

Relieving Hydraulic System Pressure

Before disconnecting or performing any work on the hy-
draulic system, all pressure in the hydraulic system
must be relieved. Park machine on a level surface, make
sure that PTO switch is OFF, lower cutting decks fully,
stop engine and engage parking brake. Wait for all mov-
ing parts to come to a complete stop.
To relieve hydraulic pressure in traction circuit, move
traction pedal to both forward and reverse directions. To
relieve hydraulic pressure in steering circuit, rotate
steering wheel in both directions.

Traction Circuit Component Failure

The traction circuit on Groundsmaster 4000--D and
4010--D machines is a closed loop system that includes
the piston (traction) pump, two (2) front wheel motors
and the rear axle motor. 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 compo-
nents in the circuit so it must be removed to prevent
additional component failure.
The recommended method of removing traction circuit
contamination would be to temporarily install the Toro
high flow hydraulic filter (see Special Tools in this chap-
ter) into the circuit. This filter should be used when con-
necting hydraulic test gauges in order to test traction
circuit components or after replacing a failed traction cir-
cuit component (e.g. traction (piston) pump or wheel
motor). The filter will ensure that contaminates are re-
moved from the closed loop and thus, do not cause addi-
tional component damage.
Hydraulic System
To relieve hydraulic pressure in lift circuit, start engine
and fully lower the cutting decks. Turn key switch to OFF
and remove key from the ignition switch.
System pressure in mow circuit is relieved when the
PTO switch is disengaged.
Once the Toro high flow hydraulic filter kit has been
placed in the circuit, raise and support the machine with
all wheels off the ground. Then, operate the traction cir-
cuit to allow oil flow throughout the circuit. The filter will
remove contamination from the traction circuit during
operation. Because the Toro high flow filter is bi--direc-
tional, the traction circuit can be operated in both the for-
ward and reverse direction. The filter should be
removed from the machine after contamination has
been removed from the traction circuit. See Filtering
Closed--Loop Traction Circuit in the Service and Repairs
section of this chapter for additional information on us-
ing the Toro high flow hydraulic filter.
The alternative to using the Toro high flow hydraulic filter
kit after a traction circuit component failure would be to
disassemble, drain and thoroughly clean all compo-
nents, tubes and hoses in the traction circuit. If any de-
bris remains in the traction circuit and the machine is
operated, the debris can cause additional circuit compo-
nent failure.
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