422E, 428E, 432E, 434E, 442E and 444E Backhoe Loaders Hydraulic and Steering System 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 hydraulic system.

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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.

The Line relief valves are not adjustable on the 422E and 428E machines.. If the circuit is below system pressure, replace the line relief valve for that circuit.

Note: Put identification marks on all lines, on all hoses, on all wires, and on all tubes for installation purposes. Plug all lines, all hoses and all tubes. This helps to prevent fluid loss and this helps to keep contaminants from entering the system.

Valve Identification

There is no main relief valve.

The line relief valves in the valve group are very sensitive to flow and the line relief valves cannot be accurately set with the hydraulic pump.

The line relief valves must be removed from the machine.

Prior to removing the line relief valve, perform the swing test, and the test for the implement. Then, perform the margin pressure test, the low pressure standby test and the high pressure stall test. If a function is still suspected, stall that function and listen for the line relief valve to open. If the line relief valve does not open, then the line relief valve is set above the system pressure. Check the line relief valve pressure settings in order to verify that the line relief valves are within the specifications.

Mechanical Loader controls

Illustration 1	g01626219
248-0482 Bank Valve (Three) (1) Auxiliary control valve (2) Tilt control valve (3) Lift control valve (4) Inlet manifold (5) A ports (6) B ports (7) Load signal relief valve

Note: The auxiliary control valve (2) is optional.

Pilot Loader Controls

Illustration 2	g01626234
293-8702 Bank Valve (Three) (1) A ports (2) Auxiliary control valve (3) Makeup and relief valve (5) Inlet manifold (6) Priority valve (7) Lift control valve (8) Tilt control valve (9) B ports

Illustration 3	g01626238
293-8703 Bank Valve (Three) (1) A ports (2) Auxiliary control valve (3) Makeup and relief valve (4) Load signal relief valve (5) Inlet manifold (6) Priority valve (7) Lift control valve (8) Tilt control valve (9) B ports

Note: The auxiliary control valve (2) is optional.

Pilot Backhoe Controls

Illustration 4	g01291907
266-2558 Bank Valve Gp (Eight) (1) Outlet Manifold (2) Left Stabilizer Control Valve (3) Auxiliary Control Valve (4) Extendable Stick Control Valve (5) Bucket Control Valve (6) Swing Control Valve (7) Stick Control Valve (8) Boom Control Valve (9) Right Stabilizer Control Valve (10) Pilot On/Off Solenoid Valve (11) Inlet Manifold (12) A Ports (13) B Ports (14) Signal Relief Valve

Note: The auxiliary control valve (3) is optional. The extendable stick control valve (4) is optional.

Illustration 5	g01291910
266-2568 Bank Valve Gp (Eight) (1) Outlet Manifold (2) Auxiliary Control Valve (3) Extendable Stick Control Valve (4) Bucket Control Valve (5) Swing Control Valve (6) Left Stabilizer Control Valve (7) Right Stabilizer Control Valve (8) Stick Control Valve (9) Boom Control Valve (10) Pilot On/Off Solenoid Valve (11) Inlet Manifold (12) A Ports (13) B Ports (14) Solenoid for the Sideshift Lock (15) Signal Relief Valve

Note: The auxiliary control valve (2) is optional. The extendable stick control valve (3) is optional.

Relief Valve Test

1. Use the following Steps in order to test or check the appropriate relief valve setting:

2. Lower all of the work tools and the stabilizers to the ground.

3. Stop the engine.

4. Turn the key to the ON position and move all of the control levers to all of the positions. This will release the system pressure.

5. Turn the key to the OFF position.

6. Remove the line relief valve that will be tested.

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Illustration 6	g01296672

7. Secure 288-6823 Manifold (E) in a suitable holding device.

8. Install two 030-8370 Adapters (G) and two 1P-2375 Couplers (H) in 288-6823 Manifold (E) .

9. Attach two 1P-2376 Adapters (J) to two 8F-0024 Hose Assemblies (K) .

10. Install line relief valve (F) in 288-6823 Manifold (E) .

11. Connect two 8F-0024 Hose Assemblies (K), two 3B-7722 Bushings, and 7J-8611 Elbow to 3S-6224 Electric Hydraulic Pump .

12. Connect 8T-0860 Gauge to 3S-6224 Electric Hydraulic Pump .

13. Turn the 3S-6224 Electric Hydraulic Pump to the ON position. Check for leaks at the connection.

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NOTICE
The 3S-6224 Electric Hydraulic Pump only has a 7.6 L (2 US gal) reservoir. Pump damage may result if the pump is operated with an empty reservoir.

14. Slowly increase the pressure. Record the pressure, when the line relief valve opens. Compare this pressure to Table 2.

15. Stop the pump.
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    Table 2

    Line Relief Valve Pressure Settings		Actual
    Hydraulic Circuit	432E, 434E, 442E, and 444E
    Rod End for STICK OUT	29000 kPa (4206 psi)
    Head End for STICK IN
    Extendable Stick (if equipped) Rod End for retracting the stick	26500 kPa (3844 psi)
    Auxiliary for backhoe (if equipped) Head end and Rod end	26500 kPa (3844 psi)
    SWING Swing LEFT Swing RIGHT	27000 kPa (3916 psi)
    Backhoe BUCKET DUMP	31500 kPa (4569 psi)
    Backhoe BUCKET CLOSE
    BOOM RAISE	31500 kPa (4568 psi)
    BOOM LOWER	16500 kPa (2393 psi)
    Loader Rod End for the Dump Operation	Single Tilt 29000 kPa (4206 psi)
    	Parallel Lift 27500 kPa (3989 psi)
    Loader Rod End for the Dump Operation 434E and 444E	Single Tilt machines 31500 kPa (4569 psi)
    Head End for the Tilt Back Operation of the Loader	Parallel Lift 16500 kPa (2393 psi)
    	Single Tilt 19000 kPa (2756 psi)
    Auxiliary (if equipped) for the Loader Line valve for the Head End Port B	24500 kPa (3553 psi)

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Illustration 7	g01296607
Line Relief Valve (A) Cap (B) Screw for Adjusting (C) Locknut

16. If the line relief valve is within the specification, then go to Step 18. If the line relief valve is not within the specification, then an adjustment is required.

    1. Remove cap (A). Loosen locknut (C) and turn adjusting screw (B) clockwise in order to increase pressure. Turn adjusting screw (B) counterclockwise in order to decrease pressure.

    2. Check the oil level in 3S-6224 Electric Hydraulic Pump and refill the oil if it is necessary. Repeat Steps 13, 14, 15, and 16.

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

18. Remove the line relief valve .

19. Install a new O-ring on the line relief valve .

20. Install the line relief valve to a torque of 70 N·m (50 lb ft).