The Slack Adjuster Group May Fail on Certain 770G, 772G, 773G, and 775G Off-Highway Trucks {4261} Caterpillar

Off-Highway Truck/Tractor

770G (S/N: RMA1-UP; KDH1-442,445-UP; ECM1-384,387-387,392-UP; ECX114-UP)

772G (S/N: RME1-UP; LTS1-1,465-UP; KEX1-1,103-418,429-UP; LTX1-UP)

Quarry Truck

773G (S/N: MWH1-UP; JWS447-UP; T5S126-UP; T5T1-UP)

775G (S/N: T5F104-UP; RFM1-1074,1076-UP; MJS695-UP; T5W1-UP)

Introduction

The problem that is identified below has a known solution. Use the solution that is identified below.

Problem

Illustration 1	g06362380
View of slack adjusters

The slack adjuster sensing piston seal, inside the 441-5290 Slack Adjuster Gp, is allowing oil to accumulate in the spring cavity causing hydraulic lock.

Solution

Illustration 2	g06362420
Cutaway view of slack adjuster (A) Assembled view (B) Floating piston (C) Sensing piston

Check for oil accumulation inside the sensing piston (C) spring cavity. If oil fills the sensing piston (C) spring cavity, the slack adjuster will not function properly. Rebuild or replace the slack adjuster group.

Use the 448-5566 Piston Kit to rebuild the 441-5290 Slack Adjuster Gp. Refer to the Disassemble and Assemble Manual, Slack Adjuster (Rear)-Remove and Install, Slack Adjuster (Rear)-Disassemble, Slack Adjuster (Rear)-Assemble for your machine for more information.