415F2 IL Backhoe Loader Hydraulic and Steering Systems Relief Valve (Loader) - Test and Adjust Caterpillar

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the brake system.

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Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Illustration 1	g06012767

The LS pressure tap (1) is on the block for the pump discharge pressure. Access is gained from the bottom of the machine.

Illustration 2	g06012762
(3) LS Relief Valve (2) Typical loader valve (Three Bank)

1. Install one 6V-4143 Quick Connect Coupler to each end of the 177-7860 Hose As.

2. Install one 8T-0860 Pressure Gauge with a range of 0 kPa to 40000 kPa (0 psi to 5800 psi) to the hose. Install the hose to LS pressure tap (1).

3. Engage the parking brake. Start the engine. Keep the machine in neutral.

4. Operate the hydraulics to the operating temperature range of 65° ± 5°C (149.0° ± 9.0°F).

5. Run the engine at 1200 RPM.

6. Raise the loader arms completely to the full RAISED position. For Single Tilt machines, place the loader control in the full DUMP position. Stall both the lift function in the RAISED position and the tilt function in the DUMP position at the same time. Note the indication of the pump discharge pressure in the gauge.

   Note: Relief valve (3) is installed in the inlet manifold on all the machines.

   Note: There may be air in the signal network, if there is a hesitation before reaching the relief pressure. Purge the signal lines of the air.

7. If the pressure for the relief valve is correct, then go to Step 14. If the relief pressure is not correct, then the relief valve needs adjusting.

8. Stop the engine.

9. Remove the cap on relief valve (3).
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   Illustration 3	g02788521

10. Loosen locknut (4) on relief valve (3).

11. Turn the screw (5) clockwise to increase the pressure. Turn the screw (5) counterclockwise to decrease the pressure.

12. Tighten locknut (4) to a torque of 20 N·m (15 lb ft).

13. Repeat Steps 5,6, and 7. If the relief valve cannot be set correctly, repeat Steps 9,10,11, and 12.

14. Turn off the engine and remove the test equipment.