Toro Groundsmaster 4700-D Service Manual page 95

Procedure for Lift/Lower Circuit Relief Pressure
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 fully raised. Apply the parking brake and stop en-
gine.
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. Raise and support hood to gain access to lift control
manifold (Fig. 50 or 51). Connect a 5000 PSI (350 bar)
pressure gauge with hydraulic hose attached to lift man-
ifold test port G1. Route gauge hose to allow hood to be
safely lowered.
4. Sit on the seat and start the engine. Move throttle to
full speed (2870 RPM).
5. While sitting on the seat, with the cutting decks fully
raised, monitor the pressure gauge to identify lift/lower
circuit pressure with no load. Record this pressure.
6. While remaining on the seat, depress rear of lift
switch (raise) to allow lift/lower circuit pressure to in-
crease. Momentarily hold the switch with the lift cylin-
ders fully retracted while looking at the pressure gauge
as the lift/lower relief valve opens.
GAUGE READING TO BE approximately 1600 PSI
(179 bar) higher than measured lift/lower circuit
pressure with no load from step 5 above (e.g. if
circuit no load pressure is 300 PSI (21 bar), lift/lower
relief pressure should be approximately 1900 PSI
(200 bar))
7. Release the lift switch and stop the engine. Record
test results.
8. If specification is not met, adjust or clean relief valve
located in the lift control manifold (see Lift Control Man-
ifold Service in the Service and Repairs section of this
chapter).
A. If pressure is too high, remove cap on relief valve
(Fig. 52). Adjust relief valve by rotating adjustment
socket counterclockwise (decrease relief pressure).
Groundsmaster 4500--D/4700--D
B. If pressure is too low, check for restriction in gear
pump intake line. Check the lift cylinders for internal
leakage. If pump intake line is not restricted and lift
cylinders are not leaking, remove cap on relief valve
(Fig. 52). Adjust the relief valve by rotating adjust-
ment socket clockwise (increase relief pressure).
C. If pressure is still too low after relief valve adjust-
ment, pump P4 or lift cylinder(s) should be sus-
pected of wear or damage.
9. Lower and secure hood after testing is completed.
FRONT
1. Test port G1
FRONT
2
1. Test port G1
1
1. Relief valve cap
Page 4 - - 61
GM 4500- -D
1
Figure 50
2. Relief valve
GM 4700- -D
1
Figure 51
2. Relief valve
2
Figure 52
2. Adjustment socket
Hydraulic System
2