784C and 785C Off-Highway Trucks Machine Systems Caterpillar

Removal Procedure

Start By:

1. Remove the cab front plate. Refer to Disassembly and Assembly, "Plate (Cab Front) - Remove and Install".

2. Release the air system pressure. Refer to Disassembly and Assembly, "Air Tanks (Brake) - Purge".

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In order to prevent possible personal injury, release the air pressure from the air tank before disconnecting any components of the air system.

Note: Cleanliness is an important factor. Before the removal procedure, the exterior of the component should be thoroughly cleaned. This will help to prevent dirt from entering the internal mechanism.

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Illustration 1	g00521366
This is a view of the Air Control Valve (Manual Retarder).

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Illustration 2	g00521368

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Illustration 3	g00521371

Note: Hose assembly (1) and hose assembly (2) need to be disconnected so that the hose assemblies can be pulled with the air control valve.

1. Disconnect hose assembly (1) from the supply air manifold.

2. Disconnect hose assembly (2) from the ARC double check valve.
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   Illustration 4	g00521374

3. Remove screw (3). Remove handle (4).
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   Illustration 5	g00521375

4. Remove two screws (5). Remove cover (6).
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   Illustration 6	g00521380

5. Remove screw (7).
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   Illustration 7	g00521382

6. Remove three-section grommet (9). Remove retarder air control valve (8).

   Note: Be careful not to damage the three hose assemblies as retarder air control valve (8) is removed.

Installation Procedure

Note: Cleanliness is an important factor. Before the installation procedure, all parts should be thoroughly cleaned in cleaning fluid. Allow the parts to air dry. Wiping cloths or rags should not be used to dry parts. Lint may be deposited on the parts which may cause later trouble.

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Illustration 8	g00521382

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Illustration 9	g00521380

1. Install three-section grommet (9) onto the three hose assemblies. Insert the three hose assemblies into the steering column. Install three-section grommet (9) into the steering column.

2. Use screw (7) in order to install retarder air control valve (8) to the steering column.
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   Illustration 10	g00521375

3. Use two screws (5) in order to install cover (6).
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   Illustration 11	g00521374

4. Use screw (3) in order to install handle (4).
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   Illustration 12	g00521371

5. Connect hose assembly (2) to the ARC double check valve.
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   Illustration 13	g00521368

6. Connect hose assembly (1) to the supply air manifold.

7. Charge the pressure in the air tank. Refer to Operation and Maintenance Manual, SEBU7173, "Starting with an External Air Supply" for the correct procedure.

End By:

1. Install the cab front plate. Refer to Disassembly and Assembly, "Plate (Cab Front) - Remove and Install".

2. Remove the wheel chocks. Refer to Disassembly and Assembly, "Wheel Chocks (Front and Rear) - Remove and Install".