1997/11/10 Caterpillar

New Anti Rotation Pins Used On Rear Suspension Cylinders To Improve Service Life {7218,7213,7201,7200}

Usage:

784B (5RK) Tractors;
785 (8GB),
785B (6HK),
789 (9ZC),
789B (7EK),
793 (3SJ),
793B (1HL),
793C (4AR) Off-Highway Trucks

Reference: Service Magazine; October 18, 1993; "Bearings Are Used to Prevent Seizure of Rear Suspension Cylinder Pins".

Reference: Service Magazine; May 19, 1997; "New Anti Rotation Bearing Pins and Bearing Lubrication Lines Used on Rear Suspension Cylinder Bearings to Increase Service Life".

Description of Change:

NOTE: This article replaces the May 19, 1997 Service Magazine article referenced above. The former locking mechanism designs announced therein should NOT be used any longer.

NOTE: The "Inboard Lubrication Lines" section found in the May 19, 1997 service magazine article referenced above has been republished in this article. Lubrication lines for the NEW locking mechanism design are IDENTICAL to lines used in the FORMER design.

A new locking mechanism is now used on rear suspension cylinder bearing pins to prevent bearing pin rotation within rear axle housing and truck frame bearing bores. The new anti rotation pin will increase service life of bearings between the pins and bearing bores.

Anti Rotation Pins

Illustration 1.
Typical view of block welded to rear axle housing. (AA) 60 ± 2 mm (2.362 ± 0.079 in). (BB) 88.0 mm (3.464 in). (W1) 12 mm (.472 in) fillet weld, 1.5 mm (.06 in) penetration, 4 sides. (W2) Bevel groove weld, 12 mm (.472 in), 2 sides.

Illustration 2.
Typical view of block welded to truck frame. (AA) 60 ± 2 mm (2.362 ± 0.079 in). (BB) 88.0 mm (3.464 in). (W1) 12 mm (.47 in) fillet weld, 1.5 mm (.06 in) penetration, 4 sides. (W2) Bevel groove weld, 12 mm (.472 in), 2 sides.

Illustration 3.
Typical view of anti rotation pins installed to rear suspension group. (Refer to Charts 1 through 3 for callout parts)

Adaptable To: Serviced parts for 2A-6987 and 5T-0884 Rear Suspension Groups listed in Chart 1 are effective with 784B (5RK26) Tractor and 785B (6HK804) Off-Highway Truck respectively. This change is adaptable to 784B (5RK1-25) Tractors; 785 (8GB1-Up) and 785B (6HK1-803) Off-Highway Trucks.

NOTE: For all 785B (6HK1-100), this change is only adaptable to trucks which have been serviced to include 7I-5494 bearing as described in the October 18, 1993 service magazine article referenced at the beginning of this article.

Serviced parts for 5T-4466 Rear Suspension Group listed in Chart 2 are effective with 789B (7EK654) Off-Highway Truck. This change is adaptable to 789 (9ZC1-Up) and 789B (7EK1-653) Off-Highway Trucks.

NOTE: For all 789B (7EK1-110), this change is only adaptable to trucks which have been serviced to include 8X-8654 bearing as described in the October 18, 1993 Service Magazine article referenced at the beginning of this article.

Serviced parts for 8X-2793 Rear Suspension Group listed in Chart 3 are effective with 793C (4AR253) Off-Highway Truck. This change is adaptable to 793 (9ZC1-Up), 793B (1HL1-Up) and 793C (4AR1-252) Off-Highway Trucks.

NOTE: For all 793 (3SJ1-36) and 793B (1HL1-11) Off-Highway Trucks, this change is only adaptable to trucks which have been serviced to include 8X-8654 bearing as described in the October 18, 1993 service magazine article referenced at the beginning of this article.

The following procedure may be used to update all 784B (5RK23-25) Tractors; 785B (6HK638-803), 789B (7EK498-653) and 793C (4AR80-252) Off-Highway Trucks which have already been fitted with the former anti rotation pin design as described in the May 19, 1997 service magazine article referenced above.

1. Support rear suspension cylinders with suitable lifting device before removing bearing pins and retaining hardware.

2. Disconnect lubrication lines from the upper and lower suspension cylinder bearings.

3. Remove inner and outer retainer plates from four suspension cylinder bearings

NOTE: For 784B, 785B and 789B; keep outer retainer bolts (7) and washers (8) to secure new inner retainers. For 793B, only keep outer retainer washers (8) for use with new inner retainers and bolts.

Remove all four 3T-1208 Blocks from the truck frame and rear axle housing.

4. Weld four 150-3980 Blocks (2) to truck frame and rear axle housing as shown in Illustrations (1,2).

5. Install four Pins (1) to upper and lower suspension cylinder bearings.

Illustration 4.
Typical view of outer retainer plate installed.

6. Install four Outer Retainer Plates (3) to upper and lower pins using six Bolts (6) and six Washers (5) on each plate.

7. Install four Inner Retainer Plates (4) to upper and lower pins using three Bolts (7) and three Washers (8) on each plate. Reuse hardware saved in Step 3 NOTE.

8. Reconnect lube lines.

Inboard Lubrication Lines

Changes For 784B (5RK) Tractors, 785 (8GB), 785B (6HK), 789 (9ZC), And 789B (7EK) Off-Highway Trucks

Adaptable To: Parts listed in Chart 4 have been added to the following lubrication groups:

* 2A-6729 Automatic Lubrication Group effective with 784B (5RK23) Tractor. This change is adaptable to 784B (5RK1-22) Tractor.

* 8X-8260 Automatic Lubrication Group effective with 785B (6HK638) Off-Highway Truck. This change is adaptable to all 785B (6HK102-637) Off-Highway Trucks, and to all 785 (8GB1-Up) and 785B (6HK1-101) Off-Highway Trucks which have bearings installed in rear suspension cylinder mounting bores.

* 8X-8270 Automatic Lubrication Group effective with 789B (7EK497) Off-Highway Truck. This change is adaptable to all 789B (7EK112-496) Off-Highway Trucks, and to all 789 (9ZC1-Up) and 789B (7EK1-111) Off-Highway Trucks which have bearings installed in rear suspension cylinder mounting bores.

The following additional changes to 8X-8260 and 8X-8270 Automatic Lubrication Groups are also effective with and adaptable to the models listed above:

The 5T-4385 Hose Assembly directly replaces 5T-4386 Hose Assembly previously used in 8X-8260 Automatic Lubrication Group.

The 8L-6557 Connector directly replaces 2N-1287 Elbow previously used in 8X-8270 Automatic Lubrication Group. The 6V-1813 Nipple and 8B-4884 Elbow have been removed also.

Changes For 793 (3SJ), 793B (1HL), 793C (4AR) Off-Highway Trucks

Parts listed in Chart 5 have been added to 125-4975 Grease Lines Group effective with 793C (4AR116). This change is adaptable to all 793C (4AR1-116), 793B (1HL12-Up), 793 (3SJ37-Up) Off-Highway Trucks; and to all 793B (1HL1-11) and 793 (3SJ1-36) which have bearings installed on rear suspension cylinder mounting bores.

Illustration 5.
Typical view of automatic lubrication group. See Chart 4 for list of components.