The Buffer Seal Assembly in the Steering Cylinder Group May Wear Prematurely on Certain 773G, 775G, and 777G Off-Highway Trucks {4303, 7555} Caterpillar

OEM

CAT WDS (S/N: M6J127-UP)

Off-Highway Truck/Tractor

777G (S/N: GT7190-UP; T5A1-123,300-UP; TNM1-884,1000-UP; RDR1-385,522-UP; T4Y1-210,520-UP)

Quarry Truck

773G (S/N: MWH1-UP; JWS427-UP; T5S126-UP; T5T1-UP)

775G (S/N: T5F103-UP; RFM1-UP; MJS651-UP; T5W1-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	g06312564
Typical example of steering cylinder group (1) 289-2937 Buffer Seal As

Illustration 2	g06315301
Area of wearing in cylinder head

The buffer seal assembly in the steering cylinder group may wear prematurely on the machines listed above. The premature wear is due to the fine contaminants that were bypassing the wiper seal over time and debris along with the buffer seal design allowing the fine material to erode the buffer seal groove.

Solution

Caterpillar is aware of this problem, but an Interim Repair has not been defined.

Replace 342-6559 Head with same part in 105-3357 Steering Cylinder Gp and 376-0011 Head with same part in 334-8695 Steering Cylinder Gp and in 417-2644 Steering Cylinder Gp and the respective seal kit needed to service the cylinder group currently installed on the machine.