Product Support Program For Adding Orifice Plates To The Rear Brake Cooling Return Lines On Certain 789B And 793B Trucks Caterpillar

NOTE: The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

NOTE: This Program can be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS8887" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and use "T" as the SIMS Description Code. If administered after failure, use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.

Termination Date

Problem

The rear brake hub may wear against the housing due to the increased duo-cone face load on certain 789B and 793B Trucks. New orifice plates have been added to the rear brake cooling return lines. This modification will increase the internal pressures and reduce the amount of brake hub wear on the housing.

Affected Product
Model & Identification Number

Group 1

789B (7EK283-457)

Group 2

793B (1HL205-499)

Parts Needed

Group 1

2 - 6J2680 Seal-O-Ring

8 - 8T4835 Bolt

2 -1374276 Plate

Group 2

2 - 2H6338 Seal-O-Ring

8 - 8T4140 Bolt

2 -1374275 Plate

Action Required

Remove the brake cooling lines at the hydraulic tank and install orifice plates and longer bolts.

Reference Service Magazine dated August 19, 1996, Page 9 "New Orifice Plate To The Rear Brake Cooling Return Oil Line Significantly Reduces Hub Wear".

Service Claim Allowances

Parts Disposition

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.