| Required Tools | ||
|---|---|---|
| Part Number | Part Description | Qty |
| 177-7861 | Hose As | 1 |
| 8T-0860 | Pressure Gauge (0 to 40,000 kPa (0 to 5,800 psi)) | 1 |
 |
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. |
 |
|
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. |
|
| 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, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
- Install steering frame lock.
- Release the pressure from the hydraulic system.
ReferenceRefer to Systems Operation, Testing and Adjusting, "System Pressure - Release".
- Attach the 177-7861 Hose As and 8T-0860 Pressure Gauge to pressure tap (1) .
 | |
| Illustration 1 | g01249792 |
(1) Pressure tap | |
- Start the engine and increase the temperature of the oil to normal operating temperature.
- Raise the lift arms to the maximum height.
- Increase the engine speed to high idle. Move the joystick control lever to the RAISE position.
- Observe the pressure gauge. The pressure setting of main relief valve (2) should be 22405 ± 170 kPa (3250 ± 25 psi).
Note: Do not keep the joystick control lever in the RAISE position, at the relief valve setting, more than 5 seconds. This may cause rapid heating of the hydraulic oil.
Note: If the pressure setting of the main relief valve is not at the specification, it will be necessary to adjust the main relief valve.
 | |
| Illustration 2 | g01037209 |
Main control valve (2) Main relief valve | |
 | |
| Illustration 3 | g01249794 |
Main control valve with auxiliary control valve (2) Main relief valve | |
- Lower the work tool to the ground. Stop the engine.
- Loosen locknut (3) on main relief valve (2). Turn adjusting screw (4) clockwise for an increase in pressure. Turn adjusting screw (4) counterclockwise for a decrease in pressure.
 | |
| Illustration 4 | g00912767 |
(2) Main relief valve (3) Locknut (4) Adjusting screw | |
- Tighten locknut (3). Repeat Steps 4 through 7.
- When the pressure setting of main relief valve (2) is correct, lower the work tool to the ground.
- Stop the engine. Remove the test equipment from pressure tap (1) .