950H Wheel Loader, 962H Wheel Loader and IT62H Integrated Toolcarrier Electrohydraulic System Caterpillar

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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 attachments have been lowered, 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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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock.

Machine Preparation for Troubleshooting

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the work tools to the ground.

2. Allow only one operator on the machine. Keep all personnel away from the machine or in the view of the operator.

3. Engage the parking brake.

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Illustration 1	g00893065
Typical example

4. Place the steering frame lock in the LOCKED position.

   ReferenceFor more information about preparing the machine for troubleshooting, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

Test and Adjust the Relief Valve

1. Start the engine and run the engine at high idle. Operate the control levers and move all the cylinders in order to increase the temperature of the hydraulic oil to normal operating temperature of approximately 49 to 65°C (120 to 150°F).

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Illustration 2	g00384713
Lift arm supports

2. Lower the lift arms to the ground or to the stands.

3. Turn the engine start switch to the OFF position.

4. Release the hydraulic system pressure. Refer to Testing and Adjusting, "System Pressure - Release".

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Illustration 3	g01185771
Front guard group

5. Remove the front guard group in order to access the load sensing relief valve .

   Note: The load sensing relief valve is the adjustment in order to obtain proper system pressure. Load sensing pressure is equal to the sum of the system pressure plus the margin pressure.

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Illustration 4	g01185796
The location of the remote pressure tap for system pressure.

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Illustration 5	g01185867
Typical example Remote pressure tap for system pressure Shown with 198-4240 Digital Pressure Indicator

6. Connect 1U-5481 Pressure Gauge Group or 198-4240 Digital Pressure Indicator on the pressure tap. The pressure tap is located on the right side of the machine on the non-engine end frame near the articulated hitch.

Note: In the following steps, do not keep the lift control lever in the RAISE position for more than five seconds while the pressure is at the relief setting.

7. Start the engine. Raise the work tool to the maximum height. Hold the lift control lever in the full RAISE position.

8. Increase the engine speed to high idle. Observe the pressure gauge with the lift control lever in the RAISE position.
   • On a standard machine, the pressure setting for the system pressure should be 27580 ± 690 kPa (4000 ± 100 psi).

   • On a logging machine, the pressure setting for the system pressure should be approximately 27580 ± 690 kPa (4000 ± 100 psi).

   Note: If the system pressure is correct, proceed to Step 10. If the system pressure is not correct, adjust the load sensing relief valve in order to obtain the correct system pressure. Proceed with the following steps in order to adjust the load sensing relief valve.

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   Illustration 6	g01185925
   Location of the 247-8632 Relief Valve ( Load Sensing)

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   Illustration 7	g01185909
   (1) Adjustment screw (2) Locknut

   1. Position the work tool on the ground or position the lift arms on the lift arm supports. Turn the engine start switch to the OFF position.

   2. Always, turn adjustment screw (1) clockwise in order to adjust the pressure. This will compensate for any internal friction inside the valve that would oppose the setting of the bias spring. For example, if the adjustment screw needs to be turned counterclockwise by 1/2 turn in order to decrease the pressure, turn the adjustment screw counterclockwise by one full turn. Then, turn the adjustment screw clockwise by 1/2 turn.

   3. Loosen locknut (2) . Turn adjustment screw (1) clockwise in order to increase the pressure setting. One quarter turn will increase the relief valve setting by 1310 kPa (190 psi). Turn adjustment screw (1) counterclockwise in order to decrease the pressure setting of the relief valve. One quarter turn will decrease the relief valve setting by 1310 kPa (190 psi).

   4. After adjustment screw (1) is turned for an adjustment, hold adjustment screw in place and tighten locknut (2) to a torque of 12 ± 2 N·m (106 ± 18 lb in).

   5. Repeat Steps 7 and 8.

9. If the pressure setting is not correct, repeat Steps 8.a through 8.e.

10. If the pressure setting is correct, position the work tool on the ground or position the lift arms on the stands.

11. Turn the engine start switch to the OFF position.

12. Release the hydraulic system pressure. Refer to Testing and Adjusting, "System Pressure - Release".

13. Remove the test equipment.

14. Install the front guard group on the machine.

15. Start the engine and remove the lift arms from the stands. Position the work tool on the ground. Turn the key start switch to the OFF position.

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Illustration 8	g00893707
Typical example

16. Place the steering frame lock in the STORE position.