Planet Shaft Assemblies May Be Improperly Manufactured on Certain 797, 797B, and 797F Off-Highway Trucks {3030, 3160} Caterpillar

Off-Highway Truck/Tractor

797 (S/N: 5YW1-UP)

797B (S/N: JSM1-UP)

797F (S/N: LAJ659-UP; WSP1-UP; LTZ1-UP)

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.

Problem

Some 562-9597 Planetary Shaft Assemblies may have been improperly manufactured. The issue can be a combination of inadequate heat treating, and an oversized shaft outer diameter. Being over sized, the planetary shaft assemblies would be difficult to install into the transmission carrier. Being over sized would also cause difficulties installing the planet bearings over the planetary shaft assemblies inside the planet gear bore. The planet shaft assemblies are used in all 797 series transmissions and arrangements.

Solution

Show/hide table

Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.

Inspect all loose 562-9597 Planet Shaft Assemblies for planet shaft hardness. A correctly manufactured planet shaft surface hardness should be a minimum 60 HRC. An inadequately heat-treated planet shaft would measure 20 to 23 HRC. If the planet shaft surface hardness is inadequate, measure the outer diameter of the planet shaft with a suitable tool. The correct diameter of the planet shaft is 47.193 ± 0.006 mm (1.85799 ± 0.00024 inch). The 562-9597 Planet Shaft Assemblies is used in train 3 of the input planetary, and train 4 of the output planetary for all 797 series transmissions.

Note: Only loose, uninstalled 562-9597 Planet Shaft Assemblies are suspect for heat treat and size conformance issues. An oversized planet shaft would be difficult to install in the planet carrier with planet bearings. That fact indicates that an installed suspect planet shaft is unlikely.

Refer to the hardness check information that follows for additional information about testing the planet shaft surface hardness. Replace any 562-9597 Planet Shaft Assemblies that do not have a minimum surface hardness of 60 HRC.

562-9597 Planet Shaft Assemblies Hardness Check Information

Show/hide table

Illustration 1	g06421982
Portable hardness test (1) End face of the 562-9597 Planet Shaft Assembly

1. Use a portable hardness tester. If a portable hardness tester is used, the end faces (1) must be properly cleaned. Refer to Illustration 1.

2. The portable hardness tester must be able to output an HRC value.

3. If the portable hardness tester measures near 20 HRC, then the planet shaft assembly must be checked on a dedicated tester. A correctly manufactured planet shaft surface hardness should be a minimum 60 HRC.

4. Location of the hardness test - end of the shaft

5. Cleanliness, any residue on the surface such as oil, soot, or grease must be removed before testing.