| Required Tools | ||
|---|---|---|
| Part Number | Part Description | Qty |
| 8T-0861 | Pressure Gauge | 1 |
| 6V-3014 | Hose | 1 |
| 6V-3989 | Unvalved Nipple | 1 |
| 6V-4143 | Coupler Assembly | 2 |
- Prior to any adjustment, refer to the "Preparations" section in Testing and Adjusting, "Operational Checks".
- Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".
- Connect a 60000 kPa (8600 psi) pressure gauge to pressure tap (1) .
| 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 Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
 | |
| Illustration 1 | g00917654 |
The pressure tap is located behind the left rear access door. (1) Main pump pressure | |
- Start the engine.
- Place the engine speed dial in position 10.
- Turn the signal limiter valve inward until the valve contacts the stop.
- Increase the main relief valve pressure to a maximum of 42500 kPa (6165 psi). Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".
- Increase the boom relief valve (head end) (2) to a maximum of 42500 kPa (6165 psi).
 | |
| Illustration 2 | g00842719 |
Main control valve (2) Boom relief valve (head end) | |
- Turn the adjustment screw (3) of one of the boom lowering control valves (valve (A) ) inward by one turn. This will increase the pressure setting higher than the setting of the line relief valve in the other boom lowering control valve (valve (B) ).
Note: In the following steps, the boom lowering control valves are referred to as valve (A) and valve (B).
 | |
| Illustration 3 | g00916830 |
(3) Adjustment screw for boom lowering control valve | |
Test
- Move the joystick to the full BOOM RAISE position until the boom cylinders are fully extended.
- While the joystick is in the full BOOM RAISE position, check the pressure at pressure tap (1). This is the pressure setting of valve (B). Refer to Testing and Adjusting, "Specifications" in this manual for the correct pressure.
Adjust
- If the pressure for the boom lowering control valve is incorrect, turn the adjustment screw at valve (B) in order to adjust the boom lowering control valve.
- Turn the adjustment screw of valve (A) outward by two turns. This will decrease the pressure setting below the setting of the adjusted valve (valve (B) ). While the joystick is in the full BOOM RAISE position, slowly turn the adjustment screw inward until the pressure at pressure tap (1) stops increasing.
Note: This will bring the settings of both valves to the same approximate level.
Note: The setting of valve (A) could be lower than the setting of valve (B) if the adjustment screw at valve (B) is turned and the pressure at pressure tap (1) does not change. If this occurs, repeat the procedure on the other valve (valve (A) ). Make sure that there is not a mechanical failure with the valve.
- Adjust the boom relief valve (head end) to the original setting. Refer to Testing and Adjusting, "Main Control Valve - Adjust (Implement Control Spools)".
- Adjust the main relief valve to the original setting. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".
- Adjust the signal limiter valve to the original setting. Refer to Testing and Adjusting, "Relief Valve (Signal Limiter) - Test and Adjust".