Relieving Hydraulic System Pressure; Traction Circuit Component Failure - Toro GroundsmasterR 4300-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, lower
cutting decks fully, stop engine and engage parking
brake.
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.
System pressure in cutting circuit is relieved when the
cutting decks are disengaged.

Traction Circuit Component Failure

The traction circuit on Groundsmaster 4300--D ma-
chines is a closed loop system that includes the piston
(traction) pump and four (4) wheel motors. If a compo-
nent in the traction circuit should fail, debris and contam-
ination from the failed component will circulate
throughout the traction circuit. This contamination can
damage other components in the circuit so it must be re-
moved to prevent additional component failure.
The recommended method of removing traction circuit
contamination would be to temporarily install the high
flow hydraulic filter (see Special Tools in this chapter)
into the circuit. This filter should be used when connect-
ing hydraulic test gauges in order to test traction circuit
components or after replacing a failed traction circuit
component (e.g. traction (piston) pump or wheel motor).
The filter will ensure that contaminates are removed
from the closed loop and thus, do not cause additional
component damage.
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-
Hydraulic System
To relieve hydraulic pressure in lift circuit, turn ignition
switch to ON (do not start engine) and fully lower the cut-
ting decks. After decks are fully lowered, turn ignition
switch to OFF and remove key from the switch.
IMPORTANT: If machine will be serviced on a lift or
at an elevated position, fully lower the cutting decks
after the machine has been raised to ensure that the
lift cylinders are fully extended. Pressure will be
maintained in the lift cylinders unless they are fully
extended.
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.
NOTE: The traction pump case drain could allow any
debris in the traction circuit to contaminate other hydrau-
lic circuits on the machine.
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