1996/01/29 Caterpillar

768C (02X),
772B (64W),
776C (2TK),
784B (5RK) Tractors;
771C (3BJ),
775B (7XJ) Quarry Trucks;
769B (35W),
773B (63W),
777B (4YC),
777C (4XJ, 8JL),
785B (6HK),
789B (7EK),
793B (1HL) Trucks

SUPPLEMENT: 05\06\96

Service Magazine; January 29, 1996; Page 6;"Wheel Bearing Adjustment Intervals" for 771C and 775B Quarry Trucks, 768C, 772B, 776C and 784B Tractors, and 769C, 773B, 777B, 777C, 785B, 789B and 793B Trucks.

Disregard the January 29, 1996 Service Magazine article. The information in that article is superceded by an article with the same title in this issue.

--------------- END SUPPLEMENT ---------------

NOTE: Various publications (Operation & Maintenance Manuals, Service Magazines, Service Manuals, etc.) have been released with recommended intervals between wheel bearing adjustments. This article supersedes all previous publications with reference to these recommended periods or intervals between adjustments. Refer to specific criteria and correct chart for applicability of wheel bearing adjustment intervals for each individual truck.

Wheel bearings DO NOT need to be adjusted or inspected until scheduled overhaul (10,000-12,000 hours) or symptoms of an obvious failure appear. Effective IMMEDIATELY, previously recommended wheel bearing adjustments at 2,000 hours and every 4,000 hours thereafter, are no longer required for any Off-Highway Truck manufactured.

Specific Criteria:

* (A) within the below stated PIN numbers ranges.

* (B) those equipped with all of the parts noted below.

* (C) trucks refitted with the REMAN Wheel Arrangements.

Conditions Requiring Adjustment Or Indicating Potential Early Failure For All Trucks:

An adjustment or failure may be indicated by one or any combination of the following:

1. Amount of metal found on the magnetic plug is found to be higher than normal.

NOTE: Magnetic wheel plugs attract metallic flakes in the wheel oil. A failure is indicated by an increased amount of metallic flakes on the magnetic plug. A weekly inspection of these magnetic wheel plugs is STRONGLY recommended.

2. Transfer of oil (internally or externally).

3. Sudden increase in particle count size or elevated concentrations of iron or nickel found in SOS samples.

NOTE: Oil samples taken to measure particle count can indicate wheel bearing failure is imminent. Sudden elevated concentrations of iron or nickel noted in the wheel compartment SOS samples can also be an indicator of a failure is imminent.

4. Scheduled overhaul or failure.

Additional Service Information For 784B Tractors, 785B And 789B Trucks ONLY

Wheel deflection measurements can:

* (A) verify a normal wheel condition

* (B) indicate abnormal wear of other various wheel parts which can lead to a wheel bearing failure.

NOTE: Wheel deflection measurements for 784B Tractors, 785B and 789B Off-Highway Trucks should be recorded on new/rebuilt wheel stations and new trucks. Wheel deflection measurements should then be performed at 1,000 hour intervals or less. These records should be kept and reviewed on a regular basis.

The machines and components in which these recommendations apply are listed in the following charts.