Service Manual

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Groundsmaster 4500--D/4700--D Hydraulic System (Rev. A)Page 4 -- 51

Procedure for Traction A ssist (RV2) Pressure Test

1. Make sure hydraulic oil is at normal operating tem-

perature by operating the machine for approximately 10

minutes. Make sure the hydraulic tank is full.

2. Park machine on a level surface with the cutting units

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 gauge to counterbalance test

port on power down and traction assist manifold under

operator’s seat (Fig. 51). Also, connect a 5000 PSI

gauge to forward traction port on traction circuit hydrau-

lic tube (Fig. 52).

4. Start the engine and put throttle at full engine speed

(2800 +

50 RPM) with no load on the system. Do not en-

gage the cutting units.

5. Sit on seat, apply brakes fully, and slowly depress the

traction pedal in the forward direction. While pushing

traction pedal monitor both pressure gauges.

6. As traction circuit pressure reaches approximately

1800 PSI, directional valve (PD3) should shift. This shift

will allow counterbalance hydraulic flow to be directed to

the traction assist valve (RV2). While maintaining trac-

tion circuit pressure, look at pressure reading on gauge

connected to the counterbalance test port:

GAUGEREADINGTOBE650 to 750 PSI.

7. Adjustment of the traction assist valve (RV2) can be

performed as follows:

NOTE: Do not remove the valve from the hydraulic

manifold for adjustment.

A. To increase pressure setting, loosen the locknut

and turn the adjusting screw on the relief valve in a

clockwise direction. A 1/8 turn on the dial will make a

measurable change in pressure (Fig. 45).

B. To decrease pressure setting, loosen the locknut

and turn the adjusting screw on the relief valve in a

counterclockwise direction. A 1/8 turn on the dial will

make a measurable change in pressure (Fig. 45).

C. Recheck pressure and readjust as needed.

1. Traction assist manifold (GM 4500--D shown)

2. Counterbalance test port

Figure 51

1. Forward traction port (faces forward)

Figure 52

1. GM 4500--D traction assist manifold

2. GM 4700--D traction assist manifold

3. Traction assist valve (RV2)

Figure 53

Hydraulic

System