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

Removal Procedure

Start By:

1. Remove the cab rear cover. Refer to Disassembly and Assembly, "Cover (Cab Rear) - 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.

Note: Put identification marks on all hose assemblies and on all tube assemblies for installation purposes. Plug all hose assemblies and all tube assemblies. This helps to prevent fluid loss and this helps to prevent contaminants from entering the system.

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Illustration 1	g00520724

1. Remove bolt (2) and the clip from pressure protection valve (1).
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   Illustration 2	g00520726

2. Disconnect hose assemblies (3), (4), (5) and (6).
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   Illustration 3	g00520737

3. Remove bolt (7) and the washer in order to remove pressure protection valve (1).

4. If necessary, remove the fittings from pressure protection valve (1).

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 4	g00520737

Note: Apply 5P-3413 Pipe Sealant to the threads of the fittings that are used during the installation procedure.

1. If necessary, install the fittings onto pressure protection valve (1).

2. Use one bolt (7) and the washer in order to install pressure protection valve (1).
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   Illustration 5	g00520726

3. Connect hose assemblies (6), (5), (4) and (3).
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   Illustration 6	g00520724

4. Position the brake air pressure sensor onto pressure protection valve (1). Install bolt (2) and the clip to pressure protection valve (1), as shown.

5. 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 rear cover. Refer to Disassembly and Assembly, "Cover (Cab Rear) - Remove and Install".

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