325B Excavator Machine Systems Caterpillar


Relief Valve (Pilot) - Remove and Install

Usage:

325B L 1GS

Removal Procedure

Note: The pilot relief valve is installed in the pilot manifold which is located behind the right rear access door of the main hydraulic pump compartment.


NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products.

Dispose of all fluids according to local regulations and mandates.


    ------ WARNING! ------

    At operating temperature, the hydraulic oil is hot and under pressure. Hot oils can cause burns.

    To prevent possible personal injury, release the pressure in the implement hydraulic circuit (boom, stick, bucket, and swing), travel circuits, and the hydraulic oil tank at the filler cap before any hydraulic lines or components are disconnected or removed.

    Remove the filler cap only when the engine is stopped and the filler cap is cool enough to touch.


  1. Release the hydraulic system pressure. Refer to Disassembly and Assembly, "Hydraulic System Pressure - Release" in this manual.


    Illustration 1g00537889


    Illustration 2g00372875

    Note: Oil will drain out of the pilot manifold when the pilot relief valve is removed. Place a suitable container under the pilot manifold in order to contain the oil.

  2. Use the following procedure to remove pilot relief valve (1) from the pilot manifold.

    1. Remove cartridge (8), spring (7), spool (3), and poppet (2) from the pilot manifold.

    2. Remove O-ring seal (5) and plug (4) from the cartridge.

    3. Remove the O-ring seal and the backup ring from the plug.

    4. Remove nut (9) and screw (6) from the cartridge.

Installation Procedure

Note: Make sure that all of the parts of the pilot relief valve are clean and free of dirt and debris. Put clean hydraulic oil on the components prior to installation.



    Illustration 3g00537889


    Illustration 4g00372875

  1. Use the following procedure to install pilot relief valve (1) in the pilot manifold.

    1. Temporarily install nut (9) and screw (6) in cartridge (8). Check the condition of O-ring seal (5). If the O-ring seal is damaged, use a new part for replacement. Install O-ring seal (5) on the cartridge.

    2. Check the condition of the backup ring and the O-ring seal for plug (4). If the backup ring and the O-ring seal are worn or damaged, use new parts for replacement. Install the backup ring and the O-ring seal on plug (4). Install plug (4) in the cartridge.

    3. Install spool (3) in poppet (2). Install spring (7) and poppet (2) in the cartridge.

  2. Install pilot relief valve (1) in the pilot manifold. Tighten cartridge (8) to a torque of 80 ± 8 N·m (60 ± 6 lb ft).

  3. Check the oil level in the hydraulic oil tank. Fill the hydraulic oil tank with oil to the correct level. Refer to Operation and Maintenance Manual, "Lubricant Viscosities" for the proper oil viscosity and Operation and Maintenance Manual, "Hydraulic System Oil Level - Check" for the correct filling procedure.

  4. Adjust the pilot relief valve pressure. Refer to Testing and Adjusting, SENR8961 for the correct adjustment procedure. After adjustment of the pilot relief valve pressure, tighten nut (9) to a torque of 16 ± 1 N·m (12 ± 1 lb ft).

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