Toro Groundsmaster 4700-D Service Manual page 77

NOTE: The traction charge circuit is designed to re-
place loss of hydraulic fluid from the closed loop traction
circuit.
Procedure for Traction Circuit Charge 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 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 onto
charge pressure test port G located on the bottom of the
filtration and charge control manifold under right side
frame rail (Fig. 33).
4. Start the engine and put throttle at full engine speed
(2870 RPM) with no load on the hydraulic system.
GAUGE READING TO BE 210 to 300 PSI (14.5 to
20.6 bar)
5. Stop engine and record test results.
6. If there is no pressure or pressure is low, check for
the following:
A. Restriction in pump intake line.
B. Charge relief valve in filtration and charge control
manifold is leaking (see Filtration/Charge Control
Manifold Service in the Service and Repairs section
of this chapter).
C. If necessary, check for internal damage or worn
parts in gear pump P3 (see Gear Pump P3 Flow Test
in this section). NOTE: Steering and lift/lower circuits
would also be affected if gear pump P3 is worn or
damaged.
Groundsmaster 4500--D/4700--D
7. Also, with the pressure gauge still connected to the
charge pressure test port, monitor the gauge reading
while operating the machine in forward and reverse.
Start the engine and put throttle at full engine speed
(2870 RPM). Apply the brakes and push the traction
pedal forward, then reverse.
GAUGE READING TO BE within 20% of no- -load
charge pressure measured in step 4 above (e.g.
if charge pressure in step 4 is 250 PSI (17.2 bar),
charge pressure in forward or reverse should be
from 200 to 250 PSI (13.8 to 17.2 bar)
8. If charge pressure is good under no load, but drops
below specification when under traction load, the piston
(traction) pump, front wheel motors and/or rear axle mo-
tor should be suspected of wear and inefficiency. When
the pump and/or traction motor(s) are worn or damaged,
the charge pump is not able to keep up with internal leak-
age in traction circuit components.
9. When testing is completed, disconnect pressure
gauge from manifold test port.
2
3
1. Right side frame rail
2. Filtration manifold
Page 4 - - 43
1
Figure 33
3. Test port location
Hydraulic System