631K and 637K Wheel Tractor-Scraper Systems Relief Valve (Steering Cylinder Crossover)

At operating temperature, the hydraulic oil tank is hot and under pressure.
Hot oil and components can cause personal injury. Do not allow hot oil or components to contact skin.

Before installation or removal of any hydraulic test equipment, relieve the pressure in the hydraulic tank by slowly loosening the filler cap.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates.

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NOTICE

Do not turn the steering wheel when the engine is running and a low pressure gauge has been installed in the steering circuit. If the steering wheel is turned, the pressure of the oil to the steering cylinders will be too high for a low pressure gauge.

Specifications

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Table 1
Steering Cylinder Crossover Relief Pressure
Date	Equipment ID Code
	Pressure Specification	Actual
High Idle	17800 ± 800 kPa (2582 ± 116 psi)

Introduction

This procedure will test the setting of the steering crossover relief valve.

Required Tools

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Illustration 1	g02601777

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Table 2
Tool	Item	Part Number	Description	Qty
B		198-4240	Digital Pressure Indicator Gp
	B1	198-4234	Digital Indicator	1
	B2	251-9600	Pressure Sensor Gp (0 to 68,900 kPa (0 to 10,000 psi))	2
	B3	198-4236	Adapter Cable As	2

Machine Preparation

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 and lower the apron onto the bowl. Shut off the engine.
Slowly loosen the filler cap for the hydraulic oil tank in order to release the pressure.

Test Procedure

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Illustration 2	g03722009
View of right-hand side cushion-hitch frame (1) Right-hand steering cylinder pressure tap (2) Left-hand steering cylinder pressure tap

To test the right-hand steering cylinder, remove the dust cap from test port (1) for the right-hand steering cylinder. Connect Tooling (B) to test port (1). To test the left-hand steering cylinder, remove the dust cap from test port (2) for the left-hand steering cylinder. Connect tooling (B) to test port (2).
Start the engine and operate the engine at LOW IDLE. Raise the bowl and release the parking brake.
Slowly steer the machine toward the right steering stop.
Increase the engine speed to HIGH IDLE.
Continue steering to the right as fast as possible into the steering stop. The right-hand steering cylinder pressure should read 17800 ± 800 kPa (2582 ± 116 psi).
Repeat Step 1 through Step 5 to test the left-hand steering cylinder.
Remove all test equipment. Install the dust caps on test ports (1) and (2).

Adjustment Procedure

Stop the machine and shut off the engine.
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Illustration 3 g03397549

Transparent view of the portion of the belly pan that has the access port.
Remove the crank case guard. For information regarding the removal of the crankcase guards refer to the Disassembly and Assembly , "Crankcase Guard - Remove and Install - Tractor" for your machine.
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Illustration 4 g03722105

View of steering control valve
(4) Steering control valve
(5) Adjustment screw
(6) Nut
Loosen nut (6) and adjustment screw (5) in order to change the steering crossover relief pressure. Turn the screw clockwise in order to increase the steering crossover relief pressure. Turn the screw counterclockwise in order to decrease the steering crossover relief pressure.
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Illustration 5 g03397549

Transparent view of the portion of the belly pan that has the access port.
Reinstall the crank case guard. For information regarding the removal of the crankcase guards refer to the Disassembly and Assembly , "Crankcase Guard - Remove and Install - Tractor" for your machine.