797 Off-Highway Truck Caterpillar

Removal Procedure

Start By:

1. Remove the steering link.

Show/hide table

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

Note: SERVICE DATA: TOOLING (ZZ) WILL NOT BE IDENTIFIED IN PHOTOGRAPHS IN THE REMOVAL OR THE INSTALLATION. THIS TOOLING IS SHOWN IN ORDER TO ASSIST THE EXPERIENCED SERVICEMAN.

Note: The following procedure is performed on the left steering cylinder. The same procedure is used on the right steering cylinder.

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 hydraulic tank into a suitable container. The steering hydraulic tank contains approximately 360 L (95 US gal). Refer to Operation and Maintenance Manual, "Steering System Oil - Change".
   Show/hide table

   Illustration 1	g00763238

2. Disconnect hose assembly (1).

3. Disconnect hose assembly (2).
   Show/hide table

   Illustration 2	g00763239

4. Disconnect hose assembly (3).
   Show/hide table

   Illustration 3	g00763240

5. Disconnect hose assembly (4).
   Show/hide table

   Illustration 4	g06223574
   Typical Example

6. Loosen the clamp and remove the cap. Repeat for the other end of the steering cylinder.
   Show/hide table

   Illustration 5	g06210157

   Show/hide table

   Illustration 6	g06210158

   Show/hide table

   Illustration 7	g06210160

7. Use Tooling (A) to support steering cylinder (7). Attach a suitable lifting device to remove steering cylinder (7). The weight of steering cylinder (7) is approximately 329 kg (725 lb).

8. Use Tooling (B) to retain ball stud (10) while nut assembly (6) is loosened.

9. Loosen two setscrews (9).

10. Loosen each jackbolt (8) 45 degrees following a one round circular pattern.

11. Loosen each jackbolt (8) 90 degrees in a circular pattern.

12. Continue loosening 90 degrees for third and successive rounds until all jackbolts (8) are loose.

13. Remove nut assembly (6).

14. Repeat Step 8 through Step 13 to remove nut assembly (5).
    Show/hide table

    Illustration 8	g06210162

    Show/hide table

    Illustration 9	g06210163
    Typical Example

15. Use Tooling (C) to remove ball stud (10). Refer to M0080743Tool Operating Manual, "Hammer Group" and , M0083627Tool Operating Manual, "Hydraulic Power Unit" for the correct procedure to remove ball stud (10).
    Show/hide table

    Illustration 10	g06210167

    Show/hide table

    Illustration 11	g06208811

16. Use Tooling (D) to remove spherical bearing race (11) from ball stud (10). Refer to Tool Operating Manual, M0069418 for additional information on using Tooling (D).
    Show/hide table

    Illustration 12	g06208819

17. Slide the end of steering cylinder (7) outward.

18. Remove two covers (13), two shims (12) and two spacers (14).

19. Repeat Step 15 through Step 18 for the other end of steering cylinder (7).
    Show/hide table

    Illustration 13	g06210807

20. Remove steering cylinder (7).

Ball Stud Inspection

Note: Cleanliness is an important factor. Before the removal procedure, the exterior of the component should be cleaned thoroughly 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 and 797F Off-Highway Trucks do not have an oversized bore.

Note: If the tapered bore is out of the specification and the tapered bore can still be salvaged, 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.

Show/hide table

Illustration 14	g00842904

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

   Table 3

   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 797F	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)

   Show/hide table

   Illustration 15	g00843601
   (1) Gel compound (2) Display screen (3) Krautkramer Branson USN 52 (4) Transducer

2. Apply standard gel compound to the transducer and to the end of the ball stud to 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 display screen. Keep the signal at "9" on the Display screen. Adjust the reflected signal for each ball stud to 100 percent of the screen height to 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 to 20 percent of the screen height.
   Show/hide table

   Illustration 16	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 display 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 display screen. Reflected signals from the drilled holes should occur approximately between 8 grid marks and 9 grid marks on the display 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

Disassembly and Assembly Information

Show/hide table

Illustration 17	g06210455

1. Apply Tooling (F) to threads of locknut (1). Tighten locknut (1) to a torque of 6000 ± 500 N.m (4425 ± 369 lb ft).

2. Lubricate sealing lips (3) with the lubricant that is being sealed.

3. Apply Tooling (G) to wiper seal groove (4) prior to assembly.

4. Tighten bolts (2) to a torque of 900 ± 100 N·m (664 ± 74 lb ft).

Installation Procedure

Note: The following procedure is performed on the left steering cylinder. The same procedure is used on the right steering cylinder.

Note: Cleanliness is an important factor. Before the installation procedure, the exterior of the component should be thoroughly cleaned. This will help to prevent dirt from entering the internal mechanism.

Show/hide table

Illustration 18	g06211470

1. Use Tooling (A) to position steering cylinder (7) for installation. The weight of steering cylinder (7) is approximately 329 kg (725 lb).
   Show/hide table

   Illustration 19	g06208819

2. Install two spacers (14), two shims (12) and two covers (13) into steering cylinder (7).
   Show/hide table

   Illustration 20	g00763612

   Show/hide table

   Illustration 21	g06210167

   Show/hide table

   Illustration 22	g06208811

3. Apply Tooling (H) to the tapered ends of two ball studs (10).

4. Use Tooling (D) to install spherical bearing race (11) and ball stud (10) into the steering cylinder. Refer to Tool Operating Manual, M0069418 for additional information on using Tooling (D).

5. Repeat Step 2 through Step 4 for the other end of the steering cylinder.
   Show/hide table

   Illustration 23	g06210157

   Show/hide table

   Illustration 24	g06210158

6. Apply Tooling (H) on the washer faces under nut assembly (6) and jackbolt (8) threads.

7. Ensure that all jackbolts (8) are flush or recessed with the bottom face of nut assembly (6).

8. Spin on nut assembly (6) by hand until nut assembly (6) seats against the washer or bottoms out.

9. Back off nut assembly (6) by a half turn but no more than 3/4 a turn to provide a gap between nut assembly (6) and the washer.
   Show/hide table

   Illustration 25	g06223690
   Typical Example

10. Use Tooling (J) and Tooling (K) to tighten jackbolts (8).

11. Tighten jackbolts (8) in a star pattern to a torque of 42 N.m (31 lb ft).

12. Tighten jackbolts (8) in a star pattern to a torque of 118 N.m (87 lb ft).

13. Repeat Step 12 until all jackbolts (8) rotate less than 10 degrees.
    Show/hide table

    Illustration 26	g06223652
    Typical Example

14. Tighten two setscrews (9) to a torque of 20 N.m (177 lb in).
    Show/hide table

    Illustration 27	g06223574
    Typical Example

15. Install the cap over nut assembly (6) and secure with the hose clamp as shown in the Illustration above.

16. Repeat Step 6 through Step 15 to install nut assembly (5).
    Show/hide table

    Illustration 28	g00763240

17. Connect hose assembly (4).
    Show/hide table

    Illustration 29	g00763239

18. Connect hose assembly (3).
    Show/hide table

    Illustration 30	g00763238

19. Connect hose assembly (2).

20. Connect hose assembly (1).

21. Fill the steering hydraulic tank with hydraulic oil to the correct level. Refer to Operation and Maintenance Manual, "Steering System Oil - Change" for the correct procedure.

End By:

1. Install the steering link.