IT28G Integrated Toolcarrier and 924G, 924Gz and 928G Wheel Loaders Steering System Caterpillar

Piston Pump (Steering and Pilot) High Pressure Stall - Test and Adjust

Usage:

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Personal injury can result from hydraulic oil pressure and hot oil.
Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.

Make sure all of the work tools have been lowered to the ground, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Table 1
Needed Tools
Part Number	Part Description	Qty
177-7860	Hose Assembly	1
6V-4144	Coupler	1
6V-4142	Unvalved Nipple	1
8T-0859	Pressure Gauge 25000 kPa (3600 psi)	1

Lower the work tool to the ground.

Stop the engine.

Engage the parking brake.

To release any steering system pressure, turn the steering wheel to the left and to the right.

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Illustration 1	g00634079
924G and 924Gz

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Illustration 2	g00906207
928G and IT28G

Remove panel (1) from the right side of the machine.

Attach one 6V-4144 Coupler to one end of the 177-7860 Hose Assembly .

Attach one 6V-4142 Unvalved Nipple to the second end of the 177-7860 Hose Assembly .

Attach one 6V-4144 Coupler to a 8T-0859 Pressure Gauge .

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Illustration 3	g00634049
924G and 924Gz (2) Test port for the steering pressure

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Illustration 4	g00906210
928G and IT28G (2) Test port for the steering pressure

The pressure reducing valve is behind panel (1) . Pressure tap (2) is on the pressure reducing valve. Remove the cap from pressure tap (2) .

Attach the 6V-4144 Coupler on the hose to pressure tap (2) on the pressure reducing valve.

Attach the 6V-4142 Unvalved Nipple to the 8T-0859 Pressure Gauge .

Start the engine.

Run the engine at HIGH idle.

Raise the work tool off the ground.

To initiate a stall condition, turn the steering wheel to the left stop. Continue to turn the steering wheel.

Read the pressure on the gauge. The pressure readings should be 20500 ± 350 kPa (3000 ± 50 psi).

To initiate a stall condition, turn the steering wheel to the right stop. Continue to turn the steering wheel.

Read the pressure on the gauge. The pressure readings should be 20500 ± 350 kPa (3000 ± 50 psi).

Lower the work tool to the ground.

Run the machine at LOW idle.

Stop the engine.

If the pressure readings are correct, proceed to step 23. If the pressure readings are not correct, adjust the pressure compensator valve. In order to adjust the pressure compensator, perform the following procedure:
1. Remove panel (3) from the left side of the machine. The pressure compensator valve (4) is attached to the top of the steering piston pump.
1. Loosen the locknut (5) . The locknut is a 13 mm (0.51 inch) nut.
1. As needed, adjust the pressure. Turn the adjusting screw (6) clockwise in order to increase the pressure. Turn the adjusting screw (6) counterclockwise in order to decrease the pressure. Adjusting screw (6) is a 3 mm (0.12 inch) screw.
  Note: When you decrease the pressure setting, turn the adjusting screw (6) counterclockwise below the needed pressure. Then, turn adjusting screw (6) clockwise to the correct pressure setting. This method of adjusting the pressure setting eliminates any free play in the threads.
1. Tighten the locknut (5) .
1. In order to make sure that the pressure is correct, perform steps 12 through 22 again.