Investigation EA89025: Vehicles

Status

CLOSED

Opened

Jun 8, 1989

Closed

Jan 29, 1990

Model years

—

Subject

Steering lockup

Component: Steering

Summary

Summary:the pe revealed that the steering system on the subject vehiclesconsists of two right angle gear boxes which are connected to the twosteering wheel assemblies in the cab.the output from these gear boxes isconnected, via u joint fitted cross shafts, to a three way right angle gearbox which receives input from either steering wheel and operates thesteering box on the chassis.analysis by the chassis manufacturer (gm)indicates probable cause of hard steering and component failure isexcessive side thrust loads in the chassis gear box.probable cause ismisalignment between the three way gear box and the chassis gear box.elgin has modified at least 12 units in the field with a dual u jointarrangement which reduces the need for a perfect shaft alignment betweenthe boxes.although no accidents have occurred, the high failure rateindicates further analysis is needed to determine if modification of theremaining units is necessary.===

An NHTSA investigation looks into whether a safety defect exists. Opening one is not a finding. Outcomes can include a recall, closure without action, or further inquiry.