The Brake Cooling and Brake Charging Pump May Lose Efficiency Prematurely on Certain 777G Off-Highway Trucks {5073} Caterpillar

OEM

CAT WDS (S/N: M6J127-UP)

Off-Highway Truck/Tractor

777G (S/N: GT7190-UP; T5A1-123,300-UP; TNM1-884,1000-UP; RDR1-385,525-UP; T4Y1-210,524-UP)

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.

Problem

The brake cooling and brake charging pump may lose efficiency on the machines listed above. This will result in low brake accumulator pressure alarms.

Solution

Caterpillar is aware of this problem, but a permanent solution is not defined yet.

Caterpillar is recommending the following suggestions:

• Check brake and parking brake accumulator pre-charge pressures.

• Inspect hydraulic tank and brake charge filter for contamination.

• If excess contamination is found, create a Dealer Solution Network (DSN) ticket quoting CPI 413375.

• Once pre-charge pressures and system cleanliness are in order, follow the below rework procedure to install 564-2050 Service Kit (pressure plate) to bring the brake charge pump efficiency back up.

Rework Procedure

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Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.

Note: The 564-2050 Service Repair Kit only contains the seals that are installed in the pressure plates. The kit does not include the shaft and body seals that are required to do a complete rebuild. If a complete rebuild is desired, a 526-9861 Seal Kit is required.

1. Remove the pump from the machine.

   Reference: Refer to Disassembly and Assembly, KENR9939, Gear pump (Hoist, Brake charge, Brake cooling) - Remove and Install for more information.

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   Illustration 1	g06319248
   Pump

2. Secure the pump in the vice by grabbing from the flat surface.

   Note: Protect the flat surface by installing an aluminum bar between the vice jaws and the pump.

   Reference: Refer to Disassembly and Assembly, KENR9939, Gear pump (Hoist, Brake charge, Brake cooling) - Disassemble for more information.

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   Illustration 2	g06319249
   (A) Bolt (B) Washer

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   Illustration 3	g06319251
   (A) Bolt (B) Washer

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   Illustration 4	g06319252

3. Remove and save the four bolts (A) and four washers (B) by using an Allen wrench. Remove the second section of the pump. Refer to Illustration 2 and Illustration 3.

   Note: If needed, a flat-headed screwdriver and mallet can be used to help disassemble the pump.

   Note: Be careful not to lose the nylon spacers near the connecting hub between first section and second section. Refer to Illustration 4.

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   Illustration 5	g06319270
   Second Section (C) Gears (D) Thrust plates (Front and rear) (E) Seals

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   Illustration 6	g06319275
   Second Section (C) Gears (D) Thrust plates (Front and rear) (E) Seals (F) Rings

4. Remove two gears (C), front thrust plate and rear thrust plate (D), two seals (E), and two rings (F) as shown in Illustration 5 and Illustration 6. Save two gears (C) and discard the rest of the parts.
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   Illustration 7	g06319276
   564-2050 Service Kit

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   Illustration 8	g06319279
   Thrust plate

5. Check the components of the replacement from 564-2050 Service Kit.

   Note: A small amount of grease has been put on the thrust plate to keep the seals in place while installing the components into the body. Use more grease if seals do not stay in place.

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   Illustration 9	g06319282
   Second Section (1) Rear thrust plate

6. Install rear thrust plate (1) into the body as shown in Illustration 9.

   Note: Ensure that seals are seated into groove.

   Reference: Refer to Disassembly and Assembly, KENR9939, Gear pump (Hoist, Brake charge, Brake cooling) - Assemble for more information.

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   Illustration 10	g06319284
   Second Section (C) Gears

7. Install gears (C) in the correct position as shown in Illustration 10. Ensure that the nylon spacer is still correctly installed in the female spline of the driving gear, add more grease if necessary.
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   Illustration 11	g06319285
   Second Section (1) Front thrust plate

8. Install front thrust plate (1) into the body as shown in Illustration 11.

   Note: Ensure that the seals do not come out of the seat. Use more grease on seal to keep in place during the assembly of the pump.

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   Illustration 12	g06319286

9. Check that the connecting hub is in the first section and install the second section on the first section and rotate the first section shaft to match the hub with gear female spline.

   Note: A mallet can be used to install the second section.

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   Illustration 13	g06319289
   (A) Bolt (B) Washer

10. Install the bolts (A) and washers (B) as shown in Illustration 13 that were saved in Step 3.

    Note: Tighten screws (A) to 140 N·m (103 lb ft).

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    Illustration 14	g06319291

11. Ensure that the shaft rotates freely prior to installing. If the shaft does not rotate freely, the thrust plate seal may be damaged and the previous steps should be repeated.

12. Reinstall the pump.