Steering Tie-Rod Failure in Dump Truck

Information:

What

A Caterpillar CAT 785 dump truck while travelling at 5 to 10 kph lost steering control when a steering ball stud socket pulled out of its tie-rod. The operator noticed that something was wrong and managed to stop the truck without further incident. Inspection of the steering system revealed that incorrect installation of the assembly had caused fretting of the threads leading to the failure.

Why

The incident was caused by incorrect component installation at some point during steering system maintenance (truck assembly, tie-rod replacement or steering geometry adjustment) caused the failure, and the clamp assembly not being aligned with one of the slots in the end of the tie-rod causing damage to the assembly.

Recommendations

Recommendations include ensuring that up-to-date maintenance information is available to persons conducting work on critical systems, checking the steering tie-rod assembly to ensure that they are correctly located and aligned, tightened to the correct torque, and in accordance with the manufacturer's instructions and recommendations, and establishing/improving appropriate maintenance schemes to ensure reliability of the steering tie-rod assembly.

Organisation:

Department of Natural Resources and Mines

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Jurisdiction:

Relates to Queensland (QLD)

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