793F Series AC Off-Highway Truck Machine Systems Caterpillar

Removal Procedure

Note: The left side steering cylinder and the right side steering cylinder are not identical. The following procedures pertain to the right side steering cylinder which has a position sensor. The left side steering cylinder does not.

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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.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

1. Release the system pressure. Refer to Operation and Maintenance Manual, "System Pressure Release".

2. Drain the hydraulic tank into a suitable container for storage or disposal. Refer to Operation and Maintenance Manual, "Hydraulic Tank Oil - Change - Steering System".
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   Illustration 1	g03538516

3. Disconnect harness assembly (1).

   Note: If necessary, remove guard (2).

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   Illustration 2	g03538517

4. Remove clips (3), spacer (4), clips (5), and the mounting hardware.
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   Illustration 3	g03538518

5. Disconnect junction block (6) and position out of the way.
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   Illustration 4	g03538519

6. Disconnect grease hose assembly (7). Remove retaining ring (8) and cap (9).
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   Illustration 5	g03538520

7. Disconnect grease hose assembly (10). Remove retaining ring (11) and cap (12).
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   Illustration 6	g03538521

8. Disconnect hose assembly (13).
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   Illustration 7	g03538522

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   Illustration 8	g03539112
   Typical Example

9. Install Tooling (A) to hold the ball stud (14) while the locknut (15) is being loosened.

10. Use Tooling (B) and Tooling (C) to remove locknut (15). Remove locknut (15).
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    Illustration 9	g06205734

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    Illustration 10	g06205097

11. Use Tooling (D) to remove ball stud (14). Refer to M0080743 Tool Operating Manual , "Hammer Group" and , M0083627 , "Hydraulic Power Unit" Tool Operating Manual for the correct procedure to remove ball stud (14). Repeat the step for the remaining steering cylinder ball studs.

12. Attach Tooling (F) and a suitable lifting device onto both ends of steering cylinder (16). Use Tooling (G) to support the steering cylinder . The weight of the steering cylinder is approximately 329 kg (725 lb).
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    Illustration 11	g03539192

13. Use a suitable press to remove spherical bearing race (17) and ball stud (14) from steering cylinder (16). Remove spherical bearing race (17) from ball stud (14). Repeat this step for the opposite end of the steering cylinder.

Installation Procedure

1. Install steering cylinder (16) in the reverse order of removal.

   1. Apply Tooling (H) onto the threads and the taper ball stud (14).

   2. Apply Tooling (H) onto the washer face of locknut (15). Tighten locknut (15) to a torque of 2550 ± 100 N·m (1881 ± 74 lb ft).

Ball Stud Inspection

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 12	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 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	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 13	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. 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 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. 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 to 20 percent of the screen height.
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   Illustration 14	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

Sensor Removal Procedure

Note: The Illustrations that are shown in the following Steps demonstrate the correct removal procedure for the sensor assembly, and these Illustrations may not represent the exact cylinder that is on your machine.

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Illustration 15	g01151971

1. Remove bolts (2) and cover (1).
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   Illustration 16	g01151970

2. Remove connector assembly (3) and sleeve (4) from the harness assembly.

3. Remove plate (5) and grommet (6).
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   Illustration 17	g03539297

4. Install Tooling (A) to sensor assembly (7).
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   Illustration 18	g01151955

5. Remove screw (8) and discard screw (8).
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   Illustration 19	g01152067

6. Remove sensor assembly (7).

7. Remove O-ring seal (9) and backup ring (10) from sensor assembly (7).

   Note: For pistons that are retained with a nut, refer to the following instructions for the removal of the magnet.

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   Illustration 20	g01154825

8. Remove retainer (11) and magnet (12) from carrier (13).

9. Remove carrier (13) from rod (14).

   Note: For pistons that are retained with a bolt, refer to the following instructions for the removal of the magnet.

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   Illustration 21	g01154827

10. Remove retainer (15) and magnet (16) from carrier (17).

11. Remove carrier (17) from bolt (18).

Sensor Installation Procedure

Note: The Illustrations that are shown in the following Steps demonstrate the correct installation procedure for the sensor assembly, and these Illustrations may not represent the exact cylinder that is on your machine.

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Illustration 22	g01152067

1. Lubricate backup ring (10) and O-ring seal (9) with the lubricant that is being sealed. Install backup ring (10) and O-ring seal (9) on sensor assembly (7).

   Note: Install backup ring (10) so that the split in backup ring (10) is in alignment with the slotted notch on the side of sensor assembly (7).

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   Illustration 23	g03539316

2. Assemble Tooling (B), as shown. Refer to Tool Operating Manual, NEHS0935.
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   Illustration 24	g03539317

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   Illustration 25	g03539319

3. Install sensor assembly (7) into Tooling (B).

4. Slide Tooling (C) over sensor assembly (7) until Tooling (C) has cleared the dimple in the side of sensor assembly (7), as shown.

   Note: If Tooling (C) is installed to the point which exposes the O-ring seal on sensor assembly (7), continue pulling sensor assembly (7) through Tooling (C) and repeat Steps 3 and 4. This will help prevent cutting the O-ring seal with Tooling (C).

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   Illustration 26	g01151972

5. Install sleeve (4) over the harness assembly.
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   Illustration 27	g03539324

6. Start by threading Tooling (D) through the wire passage of the cylinder. Continue threading Tooling (D) through the cylinder and secure Tooling (D) to the wires of sensor assembly (7), as shown.
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   Illustration 28	g03539327

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   Illustration 29	g03539328

7. With the help of another person, use Tooling (B) and Tooling (D) to guide the sensor assembly into position.

   Note: Use the alignment marks on Tooling (B) to ensure proper alignment of the sensor assembly into the counterbore. The sensor assembly should be installed with the alignment marks that are found on Tooling (B) toward the top, or in line with the wire passage in the cap if the wire passage is not in a vertical position.

8. Use Tooling (B) to push the sensor assembly into the counterbore until the pin engages the slot on the side of the sensor assembly. Make sure that the sensor assembly has engaged the counterbore correctly. Gently try to rotate Tooling (B) in both directions to ensure proper engagement of the sensor assembly.

9. Use a suitable mallet and Tooling (B) to tap the sensor assembly into the counterbore until the sensor assembly rests against the face of the counterbore.
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   Illustration 30	g01151955

10. Apply Tooling (E) to set screw (8). Install set screw (8). Tighten set screw (8) to a torque of 25 ± 6 N·m (18 ± 4 lb ft).
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    Illustration 31	g01151970

11. Install grommet (6).

12. Apply Tooling (F) to the mating surface of plate (5) and install plate (5).

13. Install sleeve (4) and connector assembly (3).
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    Illustration 32	g01151971

14. Install cover (1) and bolts (2).

    Note: For pistons that are retained with a nut, refer to the following instructions for the installation of the magnet.

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    Illustration 33	g01154825

15. Apply Tooling (G) to the threads of carrier (13) and install carrier (13) into rod (14). Tighten carrier (13) to a torque of 35 ± 5 N·m (26 ± 4 lb ft).

16. Install magnet (12) into carrier (13).

17. Apply Tooling (G) to retainer (11) and install retainer (11) into carrier (13). Tighten retainer (11) to a torque of 35 ± 5 N·m (26 ± 4 lb ft).

    Note: For pistons that are retained with a bolt, refer to the following instructions for the installation of the magnet.

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    Illustration 34	g01154827

18. Apply Tooling (G) to the threads of carrier (17) and install carrier (17) into bolt (18). Tighten carrier (17) to a torque of 35 ± 5 N·m (26 ± 4 lb ft).

19. Install magnet (16) into carrier (17).

20. Apply Tooling (G) to the threads of retainer (15) and install retainer (15) into carrier (17). Tighten retainer (15) to a torque of 35 ± 5 N·m (26 ± 4 lb ft).

Disassembly and Assembly Information

Illustration 35	g00996543

(1) Apply Tooling (B) to threads of nut. Tighten the nut to the following torque: ... 6000 ± 500 N·m (4425 ± 370 lb ft)

(2) Lubricate the sealing lips with a small amount of the lubricant that is being sealed.

(3) Apply Tooling (C) to the wiper seal groove prior to assembly.