CB-534C and CB-634C Vibratory Compactors Propel System Caterpillar

Reverse Relief Valve (High Pressure)

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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 power train.

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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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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.

Relief Valve

1. Use the following procedure before you perform testing and adjusting:
   • Place the propel control lever in NEUTRAL.

   • Place wedges of wood under each drum.

   • Make sure that the parking brake is applied.

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Illustration 1	g00593744
Needle Valve CB-534C (1) Needle valve.

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Illustration 2	g00593764
Needle Valve CB-634C (1) Needle valve.

2. Loosen the setscrew with a 5/64 allen wrench. The setscrew is located on needle valve (1). Turn the needle valve clockwise in order to close the valve.

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Illustration 3	g00594514
Propel Pump (2) Propel pump. (3) Cap for the relief valve (forward). (4) Relief valve pressure tap (reverse). (5) Relief valve pressure tap (forward). (6) Tap for the relief valve (forward).

3. Connect two 8T-0861 Pressure gauges to pressure taps (4) and (5) .

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Illustration 4	g00722335
Cross Section Of The Pump Head (3) Cap for the relief valve (forward). (6) Cap for the forward relief valve. (7) Adjustment screw. (8) Relief valve cartridge.

4. Loosen the adjuster nut on the pressure override relief valve (POR). Turn adjustment screw (7) clockwise. Turn only half of a turn. Tighten the locknut.

5. Release the parking brake.

6. Start the engine. Run the engine at high idle.

7. Move the propel control lever to the full reverse direction. Read the maximum pressure at pressure tap (4). The relief valve pressure should be 45000 ± 1380 kPa (6527 ± 200 psi).

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Illustration 5	g00594804
Relief Valve Cartridge (8) Relief valve cartridge. (9) Locking setscrew. (10) Spindle (adjuster).

8. If the relief valve pressure is not correct, the following steps must be done in order to adjust the reverse main relief valve:

   1. Stop the engine.

   2. Remove the cap on the reverse relief valve.

   3. Remove relief valve cartridge (8). Reinstall the cap on relief valve (3), so the oil does not leak during the adjustment to the cartridge.

   4. Clamp the cartridge in a soft vise jaw. See the arrows in illustration 5. Loosen locking setscrew (9) with a 3 mm allen wrench.

   5. Use a 5 mm wrench to turn spindle (10). The adjustment will be for the pressure. Turn the spindle clockwise in order to increase pressure. Turn the spindle counterclockwise in order to decrease pressure. One full revolution of spindle (10) equals 4400 kPa (638 psi).

   6. Tighten locking setscrew (9) .

   7. Remove the relief valve (reverse) from the vise.

   8. Reinstall the relief valve cartridge (reverse) (8). Install the cap (3) on the relief valve. Tighten to the torque specifications.

9. Start the engine. Check the pressure at tap (4) .

10. Stop the engine.

11. Readjust the pressure override valve back to the original position. Turn adjuster (7) counterclockwise. Turn only one half turn.

12. Turn needle valve (1) counterclockwise in order to open the valve. Tighten the setscrew on the needle valve (1) with a 5/64 inch allen wrench.

Forward Relief Valve (High Pressure)

Follow the same adjustment procedure as the Reverse Relief Valve test. Place the propel control lever in the FORWARD position. The relief valve cartridge (forward) is under the cap of the relief valve (6). The pressure is checked at the pressure tap (5) .

If the minimum low pressure is not obtainable, there is too much leakage in the internal circuit.