793C Off-Highway Truck Machine Systems Caterpillar

Ball Stud Inspection

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: Use a known damaged ball stud and a new ball stud as baselines.

Note: The following Steps will help determine the condition of the ball studs. These Steps provide instructions for the ultrasonic inspection of the steering cylinder and steering linkage ball studs. These instructions provide a means of inspecting for cracks without removing the ball studs from the machine. This procedure is not a destructive test. Perform this procedure while the ball stud is still in the steering arm or in the steering box. The recommended interval for this procedure is every 1000 service hours unless an inspection interval has been established for your particular application.

Note: The recommended replacement interval for the steering cylinder and steering linkage ball studs is between 12000 operating hours and 15000 operating hours or at the planned component rebuild of the steering cylinder. The replacement interval will depend on the following conditions: haul road condition, length of hauls, number of turns per cycle, load, and grade of the haul road.

Note: Inspect the condition of the tapered steering bore whenever a ball stud is replaced. Refer to Reuse and Salvage Guideline, SEBF8271, "Salvage of Steering Arm and Steering Arm (T-Bar) Tapers on 785, 789, 793, and 797 Off-Highway Trucks" to determine whether the tapered bore can be reused or machined to an oversized dimension.

Note: The 797B Off-Highway Truck does not have an oversized bore.

Note: If the tapered bore is out of the specification and the tapered bore is still salvageable, then an oversize ball stud may be used. If the taper is too far out of the specification, then an oversize ball stud cannot be used. In this case, either the steering arm or the steering box must be scrapped and replaced.

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Illustration 1	g00842904

1. Use a wire brush or use a scraper to thoroughly clean the end of the ball stud. A clean surface ensures a good seal with the transducer.
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   Table 2

   Critical Dimensions of Ball Studs
   Sales Model	Pt. No. of Ball Stud	A	B	C	D	E	F
   784/ 785	8X-9619	273 mm (10.7 inch)	188.283 mm (7.4127 inch)	25.9 mm (1.02 inch)	53 mm (2.1 inch)	53.75 mm (2.116 inch)	82.55 mm (3.250 inch)
   789	8X-9620	295 mm (11.6 inch)	210.283 mm (8.2788 inch)	25.9 mm (1.02 inch)	53 mm (2.1 inch)	53.75 mm (2.116 inch)	82.55 mm (3.250 inch)
   793	8X-9620	295 mm (11.6 inch)	210.283 mm (8.2788 inch)	25.9 mm (1.02 inch)	53 mm (2.1 inch)	53.75 mm (2.116 inch)	82.55 mm (3.250 inch)
   797	156-8136	295 mm (11.6 inch)	210.283 mm (8.2788 inch)	25.9 mm (1.02 inch)	53 mm (2.1 inch)	53.75 mm (2.116 inch)	82.55 mm (3.250 inch)
   797B	192-5702	341 mm (13.4 inch)	225.006 mm (8.8585 inch)	25.9 mm (1.02 inch)	80.26 mm (3.160)	79.53 mm (3.13 inch)	109.73 mm (4.320 inch)

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   Illustration 2	g00843601
   (1) Gel compound (2) CRT screen (3) Krautkramer Branson USN 52 (4) Transducer

2. Apply standard gel compound to the transducer and to the end of the ball stud. This will ensure proper contact with the transducer.

3. Set the gate at 20 percent of the screen height.

4. Use a 2.25 MHz - 5Mhz straight beam transducer. The diameter of the transducer should measure 12.7 mm (0.5 inch) to 25.4 mm (1.0 inch). The area of concern is dimension (B) for this type of defect.

5. Apply the transducer to the threaded end of the ball stud.

6. Use the range key to move the reflected signal to "9" on the CRT screen. Keep the signal at "9" on the CRT screen. Adjust the reflected signal for each ball stud to 100 percent of the screen height. This will ensure that the surface is the opposite end of the ball stud and that the surface is not the bottom of the drilled holes.

   Note: Drilled holes will reflect the signal.

7. Set the gate at 20 percent of the screen height.
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   Illustration 3	g00843670
   (B) Interruptions that are in this area will appear between the 0 grid mark and the 6.4 grid mark. (C) Interruptions that are in this area will appear between the 8 grid mark and the 9 grid mark. (G) Interruptions that are in this area will appear between the 6.5 grid mark and the 8 grid mark. (H) Cracks that are in this area CAN NOT be detected.

8. Slowly move the transducer over all surfaces of the end of the ball stud.

   Note: An indication from approximately 0 to 6.4 grid marks on the CRT screen indicates a damaged ball stud. A complete loss of the reflected signal may also indicate a damaged ball stud.

   Note: The area of concern (B) should occur approximately between 0 grid marks and 6.4 grid marks on the CRT screen. Reflected signals from the drilled holes should occur approximately between 8 grid marks and 9 grid marks on the CRT screen.

   Note: Although the ultrasonic beam spreads slightly, cracks that are in Area (H) CAN NOT be detected.

9. Identify the ball stud as an acceptable ball stud or as a damaged ball stud.

10. Document the following information.

    • Date of inspection

    • Serial number of the inspected truck

    • Part number of the inspected ball studs

    • Number of inspected ball studs

    • Number of ball studs that were damaged per truck

    • Initial of operator that performed the inspection

    • Any corrective action that was taken

Removal Procedure

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Personal injury can result from hot oil or hot components. At operating temperature, oil is hot and under pressure. Hot oil can cause burns. Remove the fill cap only when the engine is stopped, and the fill cap is cool enough to touch with your bare hand. Do not allow hot oil or components to contact skin.

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.

1. Drain the hydraulic oil from the steering system.
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   Illustration 4	g00944853
   Rod end of cylinder

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   Illustration 5	g00944846
   Head end of cylinder

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   Illustration 6	g00944854
   Rod end of cylinder

2. Disconnect lubrication hose (1) from the plug (2) at each end of the steering cylinder (4).

3. Disconnect hose assembly (3) from each end of the steering cylinder (4).
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   Illustration 7	g00944850

4. Use a screwdriver to remove retaining ring (5) and plug (2) at each end of the steering cylinder (4).
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   Illustration 8	g00944847

5. Install Tooling (A) to hold the ball stud (6) while the locknut (7) is being loosened.
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   Illustration 9	g00944851
   Shown for photo purposes

6. Use Tooling (B) to locknut (7). Remove locknut (7).
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   Illustration 10	g06201465

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   Illustration 11	g06201513

7. Use Tooling (C) to remove ball stud (6). Refer to M0080743 Tool Operating Manual , "Hammer Group" and , M0083627 , "Hydraulic Power Unit" Tool Operating Manual for the correct procedure to remove ball stud (6). Repeat the step for the remaining steering cylinder ball studs.

8. Use Tooling (D), to support the steering cylinder. The weight of steering cylinder is approximately 110 kg (243 lb).

9. Remove the steering cylinder.

10. Repeat Steps 2 through 9 to remove the remaining steering cylinder.
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    Illustration 12	g06203995

11. Use a suitable press to remove spherical bearing race (9) and ball stud (6) at each end of the steering cylinder (4).

12. Remove retaining ring (8) that holds spherical bearing race (9) to each ball stud (6). Remove the spherical bearing race (9) from each ball stud.

13. Repeat Steps 11 and 12 for the remaining steering cylinder.

Disassembly and Assembly Information

Illustration 13	g00944845

(1) Apply Tooling (F) to threads of nut. Tighten the nut to the following torque: ... 2200 ± 220 N·m (1623 ± 162 lb ft)

Lubricate the following sealing lips with a small amount of the lubricant that is being sealed: (2), (3) and (4).

(5) Apply Tooling (G) to the sealing groove prior to assembling the wiper seal.