Procedure to Improve the Coupling Adapter Group on Certain 795F AC and 795F XQ Off-Highway Trucks {3252, 4456} Caterpillar

Off-Highway Truck/Tractor

795F AC (S/N: ERM153-172,174-206,208-300)

795FAC XQ (S/N: SNT1-105)

Reference: Coupler Adapter and Mounting-Assemble section in Disassembly and Assembly, KENR8715, "795F and 795F series AC Off-Highway Truck Power Train"

Reference: Reuse and Salvage Guidelines, SEBF9338, "Inspection of Rubber Blocks for 793F AC, 794 AC, 795F AC, and MT4400D AC Off-Highway Trucks"

Reference: Special Instruction, M0079855, "Procedure for Checking Crankshaft End Play on Certain 794 and 795F Series AC Off-Highway Trucks"

Reference: Crankshaft-Type 1Crankshaft Type 2 in Specifications, KENR9187, "C175-16 Engine for 795F Series AC Off-Highway Trucks" for crankshaft end play values.

Introduction

This special instruction provides information to improve the coupling adapter group on the machines listed above.

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

Safety Section

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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.

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Failure to follow all safety guidelines prescribed in this document and by governing authorities and regulatory agencies may result in severe injury or death of personnel or machine damage.

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When removing a major component or attachment, ensure that it is properly blocked or secured before removing mounting hardware. An assembly that is disconnected without proper blocking may shift or fall, resulting in serious injury or death of personnel or machine damage.

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Personal injury or death can result from improper maintenance procedures. To avoid injury or death, follow the procedures exactly as stated below.

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Personal injury can result from improper handling of chemicals. Make sure you use all the necessary protective equipment required to do the job. Make sure that you read and understand all directions and hazards described on the labels and material safety data sheet of any chemical that is used. Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

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Climbing equipment may be required to access this service point. Refer to the Operation and Maintenance Manual, "Mounting and Dismounting" topic for safety information.

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Before servicing/performing maintenance on the machine, electrical power must be physically disconnected; battery plugs must be disconnected from the batteries, or the trailing cable must be unplugged, and warning tags and padlocks shall be applied by a certified electrician. Certified electricians shall perform or direct any electrical work, including any energized testing, repair work in controllers, motors, or other approved compartments, and shall insure that all compartments are properly closed and inspected prior to re-energization. All applicable lock out and tag out procedures must be followed.

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Do not operate the machine if any guards or covers are missing or inadequately secured. Personnel could be seriously injured or machine damage may occur.

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Observe the safe working load limits of all lifting and blocking devices and keep a safe distance from suspended/blocked loads. Personnel may be seriously injured or killed by falling loads.

Required Parts

Required Tools

Rework Procedure

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Illustration 1	g06287296
(A) 552-3724 Hub

1. Remove and retain hub (A) from adapter group.

   Note: 395-4219 Coupling Hub can be modified into 552-3724 Hub (A).

   Reference: Coupler Adapter and Mounting-Assemble section in Disassembly and Assembly, KENR8715, "795F and 795F series AC Off-Highway Truck Power Train"

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   Illustration 2	g06342187
   Cross section - 552-3724 Hub (B) Datum (C) Datum (D1) 45 degrees, 2 places (D2) radius 0.40 ± 0.25 mm (0.016 ± 0.009 inch) (D3) 340.0285 ± 0.0285 mm (13.387 ± 0.001 inch) ( 0.10 mm (0.004 inch) true position to Datum B and Datum C) (D4) 0.5 ± 0.20 mm (0.02 ± 0.008 inch) (D5) 8.5 ± 0.25 mm (0.33 ± 0.009 inch) (G1) Critical surface finish 3.2 mm (0.13 inch) (G2) Critical surface finish 6.3 mm (0.25 inch)

2. Create a counter bore using information provided in Illustration 2.
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   Illustration 3	g06287655
   552-3724 Hub (D6) 132.83 mm (5.230 inch) (D7) 115.47 mm (4.546 inch) (D8) 175.57 mm (6.912 inch) (D9) Drill 16X holes, 5.2 mm (0.20 inch) diameter, 20 mm (0.8 inch) deep and tap holes to M6 X 1, 15 mm (0.6 inch) deep (D10) 12.28 mm (0.483 inch)

3. Create 16 threaded holes as shown in Illustration 3.
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   Illustration 4	g06287678
   (A) 552-3724 Hub (1A) 552-3657 Ring

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   Illustration 5	g06352152
   (A) 552-3724 Hub (1A) 552-3657 Ring

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   Illustration 6	g06372762

4. Verify if the surface is flush all the way around by placing ring (1A) over machined hub (A) as shown in Illustration 4 and Illustration 5.

   Note: The correct chamfer is 6.096 mm (0.2400 inch) at 15 degrees with radii of 12.0 mm (0.47 inch) at the non-insertion end and 1.50 mm (0.059 inch) at the insertion end.

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   Illustration 7	g06288078
   (A) 552-3724 Hub (D) Coupling group housing

5. Clean hub (A) and coupling housing (D) completely to bare metal.

6. Lubricate the pockets of the housing that contact the silicone elements

   Note: Refer to Reuse and Salvage Guidelines, SEBF9338, "Inspection of Rubber Blocks for 793F AC, 794 AC, 795F AC, and MT4400D AC Off-Highway Trucks" for reusability of the Coupling Elements.

7. Insert hub (A) into coupling housing (D) and turn it counter clockwise as shown in Illustration 7.
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   Illustration 8	g06288099
   (D) Coupling group housing (2) 396-1559 Drive Coupling Gp (FLEXIBLE)

8. Lubricate the main elements and trailing elements (2).

   Insert first main of flexible drive coupling group (2) to coupling housing (D).

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   Illustration 9	g06288100
   (D) Coupling group housing

9. Insert first trailing element to coupling housing (D).
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   Illustration 10	g06288102
   (D) Coupling group housing

10. Insert second main to coupling housing (D) in the opposite side.
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    Illustration 11	g06288105
    (D) Coupling group housing

11. Insert second trailing to coupling housing (D) in the opposite side.
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    Illustration 12	g06288109
    (D) Coupling group housing (2) 396-1559 Drive Coupling Gp (FLEXIBLE)

12. Lubricate the remaining main elements and trailing elements and insert them in order shown above.
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    Illustration 13	g06288115
    (1B) 552-3658 Seal (1C) 552-3659 Cover Plate

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    Illustration 14	g06288131
    (1B) 552-3658 Seal (1C) 552-3659 Cover Plate

13. Clean cover plate (1C) and seal (1B).

    Lubricate and install seal (1B) into groove of cover plate (1C).

    Note: Ensure that seal (1B) is fully seated in the groove.

    Note: To assist in assembly, Loctite 480 may be used to secure seal (1B) in the groove.

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    Illustration 15	g06288138
    (D) Coupling group housing (1B) 552-3658 Seal (1C) 552-3659 Cover Plate (3) 7X-2563 Bolt (4) 154-1580 Hard Washer

14. Install cover plate (1C) and seal (1B) to coupling housing (D) using eight bolts (3) and eight hard washers (4).

15. Tighten eight bolts (3) gradually to 460 ± 60 N·m (340 ± 44 lb ft) in a star pattern.
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    Illustration 16	g06288147
    (1A) 552-3657 Ring

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    Illustration 17	g06288150
    (1A) 552-3657 Ring

16. Lubricate outer diameter and lead in chamfer of ring (1A).
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    NOTICE
    To avoid cutting the seal, do not use a sharp blade in this step.

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    Illustration 18	g06288163
    (1A) 552-3657 Ring (1B) 552-3658 Seal (T1) 7X-0465 Bolt

17. Position ring (1A) on seal (1B) using four bolts (T1) as guide pins.

    Note: Check that seal (1B) has not pulled out of the groove before trying to pull ring (1A) on with bolts (T1).

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    NOTICE
    Take caution not to pull the threads out of the star hub. If necessary, tap lightly and evenly with a hammer on ring (1A).

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    Illustration 19	g06288166
    (1A) 552-3657 Ring (T2) Palette knife

18. Tighten the bolts evenly until the entire seal is engaged.

    Note: Ensure the seal does not roll over when tightening the bolts. If the seal begins to roll over, use palette knife (T2) between ring (1A) and the seal as shown in Illustration 19.

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    Illustration 20	g06288168
    (T1) 7X-0465 Bolt (1D) 8C-8451 Bolt (1E) 9X-8256 Washer (1F) 552-3655 Deflector

19. Install deflector (1E) to ring (1A) using bolt (T1) as guide.

20. Remove all bolts (T1) and guide studs.

21. Install 16 bolts (1D) and 16 washers (1E) as shown in Illustration 20.

    Note: Confirm that ring is fully seated on the hub after bolts are fully tightened.

22. Use Loctite 243 and tighten bolts (1D) to 12 ± 3 N·m (9 ± 2 lb ft).