631K and 637K Wheel Tractor-Scraper Systems Relief Valve (Scraper Bowl) - Test and Adjust Caterpillar

Specifications

Introduction

Note: It is not necessary to perform this test on both the relief valve (scraper bowl) and the relief valve (ejector). When the bowl is set, the ejector will be set.

This test will check the bowl relief valve pressure. The Implement relief pressure is the deference between the pump supply pressure and the implement tank return pressure.

Tooling Required

Illustration 1	g01623868
Tooling (B)

Test Preparation

1. Move the machine to a smooth, horizontal location. Move the machine away from other operating machines and away from personnel. Place the transmission direction control switch in the NEUTRAL position. Engage the parking brake. Lower the bowl to the ground. Retract the ejector cylinder and disengage the cushion hitch. Shut off the engine and turn the engine start switch to the ON position. Place chocks in front of the wheels and behind the wheels.
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   NOTICE
   Perform the following steps prior to the pilot pressure diminishing. The procedure should be performed no more than 1/2 hour after the engine has been shut off.

2. Move the control levers through the full range of travel. This movement of the levers will relieve any pressure that may be present in the hydraulic system. Turn the engine start switch to the OFF position.

3. Slowly loosen the filler cap for the hydraulic oil tank in order to release the pressure.

Test Preparation

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Illustration 2	g06217860
View of the rear of the gooseneck assembly (1) Drain to hydraulic tank tap (2) Pump pressure tap

1. Remove the dust cover from pump pressure tap (2). Install a pressure sensor (B) onto pump pressure tap (2).

2. Remove the dust cover from drain to hydraulic tank tap (1). Install pressure sensor (B) onto drain to hydraulic tank tap (1).

Test Procedure

1. Warm the engine up to the normal operating temperature.

2. Slowly raise the bowl to the fully raised position and bring the engine to a HIGH IDLE. Hold the control joystick in the BOWL RAISE position. The bowl raise relief pressure shall be 25800 ± 690 kPa (3742 ± 100 psi).

Adjustment Procedure

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Illustration 3	g06217867
View of implement control valve (3) Adjustment screw (4) Lock nut

1. If the relief pressure is set to low, then loosen lock nut (4) and turn adjustment screw (3) clockwise. Turn the set screw until the relief valve pressure is 25800 ± 690 kPa (3742 ± 100 psi). Then tighten lock nut (4), and check the relief valve pressure again.