Excessive Wear of the Cross Axle Differential Lock Piston Housing and Hub{3256, 3258} Caterpillar

Articulated Truck:

735B (S/N: L4D1-UP; T4P1-UP)

740B (S/N: L4E1-UP; T4R1-UP)

740B EJECTOR (S/N: L4F1-UP; T4S1-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

Illustration 1	g03409032
152-4093 Housing in position on a differential

Illustration 2	g03409033
Piston housing assembly removed from differential. The arrow indicates the area that may wear

Illustration 3	g03409035
Example of minor wear of the piston housing

Illustration 4	g03409037
Example of extreme wear of the piston housing

Illustration 5	g03409038
Example of damage to the contact face of the 138-3638 Hub

The 152-4093 Housing may wear prematurely due to excessive contact with the 138-3638 Hub . The face of the hub that contacts the piston housing may also be damaged during the failure. Both of these components are part of the cross-axle differential lock arrangement in the front, center and rear axles on the above products. Refer to Illustrations 1, 2, 3, 4, and 5.

Solution

If an increase in iron "Fe" is found in the SOS samples for the front, center or rear differentials, change the oil and take further samples at intervals of 250 hours of operation. Three consecutive SOS samples showing high iron can point to excessive wear of the differential piston housing.

Note: If available, elevated PQI readings on the front, center, or rear differential oil samples can also point to excessive wear of the differential piston housing.

Repair

1. Refer to Disassembly and Assembly, UENR0207, "Differential and Bevel Gear (Center) - Disassemble" to remove the piston housing and hub from the differential.

Show/hide table



Illustration 6	g03409028

2. Determine the amount of wear on the piston housing by measuring the distance between the contact face and the end of the mounting posts. Refer to Dimension (A) in Illustration 6.

3. Dimension (A) must not be greater than 80 mm (3.15 inch). If Dimension A is greater than 80 mm (3.15 inch), the piston housing must be replaced with a new part.

4. If the 138-3638 Hub shows signs of galling and/or smearing as shown in Illustration 5, the hub must also be replaced with a new part.

   Note: A recommended method of measuring dimension (A) is to place a bar across two piston legs and measure down using a caliper or scale (ruler). Make sure to add thickness of the bar to the depth calculation.