Toro Groundsmaster 4700-D Service Manual page 81

NOTE: Adjustable relief valve (RV) in the 4WD/2WD
control manifold reduces rear axle motor pressure
created in down hill, dynamic braking conditions to pre-
vent rear wheel lock up.
Procedure for Rear Traction Circuit Relief (RV) Pres-
sure Test
1. Make sure hydraulic oil is at normal operating tem-
perature by operating the machine for approximately ten
(10) minutes. Make sure the hydraulic tank is full.
2. Park machine on a level surface with the cutting
decks lowered and off. Make sure engine is off and the
parking brake is engaged.
CAUTION
Prevent personal injury and/or damage to equip-
ment. Read all WARNINGS, CAUTIONS and Pre-
cautions for Hydraulic Testing at the beginning
of this section.
3. Connect a 1000 PSI (70 bar) pressure gauge to test
port G on on rear side of 4WD/2WD control manifold un-
der operator's platform (Fig. 36).
4. Start the engine and put throttle at full engine speed
(2870 RPM).
5. Operate the machine in Low speed with the cutting
decks lowered. Drive down a slope in a forward direction
and decrease pressure on the traction pedal while care-
fully monitoring the pressure gauge. Pressure should in-
crease until the relief valve lifts.
GAUGE READING TO BE 520 to 570 PSI (36 to 39
bar)
6. Relief valve (RV) is located on the left side of the
4WD/2WD control manifold in the RV port (Fig. 36). Ad-
justment of the relief valve can be performed as follows:
NOTE: Do not remove the relief valve from the hydrau-
lic manifold for adjustment.
A. To increase relief pressure setting, remove cap
on relief valve and turn the adjustment socket on the
relief valve in a clockwise direction (Fig. 37). A 1/8
turn on the socket will make a measurable change in
relief pressure.
B. To decrease pressure setting, remove cap on re-
lief valve and turn the adjustment socket on the relief
valve in a counterclockwise direction (Fig. 37). A 1/8
turn on the socket will make a measurable change in
relief pressure.
Groundsmaster 4500--D/4700--D
C. After adjustment is made, recheck relief pressure
and make additional adjustment if necessary.
RIGHT
FRONT
1. 4WD/2WD manifold
1. Relief valve cap
Page 4 - - 47
1
Figure 36
2. Relief valve (RV)
1
2
Figure 37
2. Adjustment socket
Hydraulic System
2