Required Tools     | ||
---|---|---|
Part Number     | Part Description     | Qty     |
8T-0861     | Pressure Gauge (0 to 60,000 kPa (0 to 8,700 psi))     | 1     |
6V-3989     | Fitting (TEST)     | 1     |
6V-4143     | Quick Connect Coupler     | 2     |
6V-3014     | Hose As     | 1     |
Note: Two technicians are required for this test.
Note: Prior to any adjustment, refer to the "Preparations" section in Testing and Adjusting, "Operational Checks".
Note: Prior to performing this test, the Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" must be performed.
Preparation
- Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release".
- Connect 60000 kPa (8700 psi) pressure gauges to pressure taps (1) and (2) .
NOTICE |
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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. |
Illustration 1 | g01205997 |
The remote pressure taps are located behind the left rear access door. (1) Pressure tap (Main pump pressure) (2) Pressure tap (Load sensing signal pressure) |
Illustration 2 | g01253772 |
Main Control Valve ( M313C, M315C, and M316C) (3) Main relief valve (4) Load sensing signal limiter valve |
Illustration 3 | g01205998 |
Main Control Valve ( M318C, M318C MH, M322C, and M322 MH) (3) Main relief valve (4) Load sensing signal limiter valve |
- Loosen the locknut on load sensing signal limiter valve (4). Turn the adjustment screw on the load sensing signal limiter valve clockwise until the adjustment screw contacts the stop.
Note: Do not overtighten the adjustment screw.
- Start the engine.
- Adjust the engine speed to position 5 by turning the engine speed dial.
- Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).
- Move the right joystick to the full BOOM RAISE position.
Note: Stall the boom in the BOOM RAISE position.
- Check the pressure reading at pressure tap (1). Loosen the locknut on main relief valve (3). Increase the main relief valve pressure by slowly turning the adjustment screw on the main relief valve clockwise. Continue turning the adjustment screw clockwise until the pressure at pressure tap (1) stops increasing.
- Increase boom relief valve (5) to a maximum of 42500 kPa (6165 psi).
Illustration 4 | g01206225 |
Main Control Valve (5) Boom relief valve (Head end) |
- Turn adjustment screw (6) 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 5 | g01250425 |
(6) Adjustment screw (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 (2). 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 (2) 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 (2) 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, "Relief Valve (Line) - Test and Adjust (Implement)".
- 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".