793B TRUCK MACHINE SYSTEMS Caterpillar

Hoist Cylinders

Usage:

Remove & Install Hoist Cylinders

1. Drain the oil from the hydraulic tank.

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Make sure all the pressure in the hydraulic system has been released before disconnecting any oil lines.

Typical Example

2. Disconnect oil lines (1) from the bottom of the hoist cylinder.

3. Disconnect lubrication line (2) from the hoist cylinder.

Typical Example

4. Fasten chain (4) to hoist cylinder (3) to support the cylinder when the top pin is removed.

Typical Example

5. Remove the bolts and bar (5) that hold the top pin in place.

Typical Example

6. Remove the top pin with tooling (A). Remove the two spacers.

Typical Example

7. Install tool (B) on the bucket of a wheel loader or a suitable hoist.

8. Put tape on the hoist cylinder rod for protection when tool (B) is installed. If a nylon strap is used, the tape is not necessary.

9. Fasten a chain or nylon strap and tool (B) to hoist cylinder (3). Support the weight of the hoist cylinder with tool (B).

Typical Example

10. Remove the bolts and cover (6) from the lower hoist cylinder pin.

Typical Example

11. Remove bolt (7) and plate (8).

12. Use the three threaded holes at the bottom of the hoist cylinder to install tooling (C) as shown.

13. Remove hoist cylinder (3) from the machine. The weight of hoist cylinder is 1150 kg (2535 lb).

NOTE: The following steps are for the installation of the hoist cylinders.

14. Install tool (B) on the bucket of a wheel loader.

15. Fasten tool (B) to a hoist cylinder (3). Put the hoist cylinder in position on the bottom pin.

16. Install plate (8) with bolt (7).

17. Install cover (6) with three bolts.

18. Align the end of the hoist cylinder with the pin boss in the truck body, and install the top pin with the two spacers.

19. Install bar (5) and the bolts to hold the pin in place.

20. Connect oil lines (1) to the bottom of the hoist cylinder.

21. Connect lubrication line (2).

22. Fill the hydraulic tank with oil to the correct level. See the Operation & Maintenance Manual.

Disassemble Hoist Cylinders

NOTE: Photos are from a 785 Truck. Procedures are similar for a 793B Truck.

Start By:

a. remove hoist cylinders

NOTE: Make sure all of the oil is removed from the cylinder before it is disassembled.

1. Put the hoist cylinder in position on tooling (A) as shown.

2. Remove bolts (1) and the washers. Use tool (A), and pull cylinder assembly (3) away from head (2).

3. Put two wood blocks (5) 152.4 mm (6.00 in) long between the cylinder assembly and head (2) as shown. Use tooling (A) to push head (2) off of cylinder (4).

4. Use tooling (A), and pull cylinder assembly (3) part way off of cylinder (4).

5. Put support (6) in position under cylinder (4). Remove cylinder assembly (3) the rest of the way.

6. Fasten a hoist to cylinder assembly (3), and remove it from tooling (A). The weight of the cylinder assembly is approximately 238 kg (495 lb).

7. Put tape around cylinder (4) to protect the cylinder when it is fastened to tooling (A).

8. Fasten cylinder (4) to tooling (A) as shown.

9. Remove ring (8) from the cylinder.

10. Remove bolts (9) that hold piston (7) to the rod assembly.

11. Use tooling (A), and pull the rod assembly part way out of the cylinder.

12. Put two wood blocks (10) in position between the rod assembly and piston (7) as shown. Use tooling (A), and push the piston out of the cylinder.

13. Remove rings (11) and (13) and seal assembly (12) from piston (7).

14. Use tooling (A) to pull cylinder (4) part way off of rod assembly (14). Put support (6) in position under rod assembly (14) as shown. Pull the cylinder off of the rod assembly.

15. Remove wiper (18), seal (15), seal (17) and ring (16) from the cylinder.

16. Fasten a hoist and tool (B) to head (2). Remove the head from the rod assembly. The weight of the head is approximately 56 kg (123 lb).

17. Remove O-ring seal (22) and ring (23) from the outside of head (2).

18. Remove seals (19) and (20) and wiper (21) from the inside of head (2).

Assemble Hoist Cylinders

NOTE: Photos are of a 785 Truck. Procedures are similar for a 793B Truck.

NOTE: Put clean hydraulic oil on all O-ring seals, seals and wipers before they are installed. Also, put clean hydraulic oil on the rod assembly and cylinder.

1. Put seals (19) and (20) and wiper (21) in position in the inside of head (2). The thick seal (19) goes toward the inside (pressure side) of the head. The thin seal (20) goes to the outside (atmosphere side of the head). Install wiper (21) with the lip toward the outside.

2. Install O-ring seal (22) and back-up ring (23) on the outside of head (2). Install the O-ring seal toward the inside (pressure side) of the head.

3. Fasten a hoist and tooling (B) to head (2). Put the head in position on the rod assembly as shown.

4. Install ring (16), seals (15) and (17) and wiper (18) in the grooves in the end of the cylinder. The thick seal (17) goes toward the inside of the cylinder. The thin seal (15) goes toward the outside of the cylinder. Install wiper (18) with the lip toward the outside of the cylinder.

5. Put head (2) in position on cylinder (4).

6. Use tool (A) to push cylinder (4) on rod assembly (14).

7. Put rings (13) and (11) and seal assembly (12) in position in the grooves in piston (7).

NOTE: Make sure the bolt holes in piston (7) are in alignment with the bolt holes in the rod assembly before it is installed.

8. Align the bolt holes in piston (7) with the bolt holes in the rod assembly, and put the piston in position in the end of the cylinder. Use a soft hammer, and carefully install the piston in the cylinder.