CONFIDENTIAL TIBU4306-00

There have been reports of low brake pressure warnings sounding on the listed machines. The Operation and Maintenance Manual advises the operator to shut the machine down when the low brake pressure warning sounds. On 740 EJECTOR machines the problem may manifest itself by slow retraction of the ejector blade.

Investigation into the problem initially leads the serviceman to believe that the cause of the problem is the 172-9322 Pump Gp (725 and 730) or the 187-9090 Pump Gp (735, 740 and 740 EJECTOR). There have been occurrences where the pump has been changed and the fault is still apparent.

Further investigation into the cause of the failures, on machines where changing the pump failed to correct the fault, has revealed that an internal O-ring seal in the brake relief valve cartridge (Part number 224-4530 in the 224-1209 Check and Pressure Reducing Valve, refer to Illustration 1) has split. This allows pressure oil to leak back to tank internally and results in low brake pressure or the inability of the pump to maintain brake pressure. For the location of the failed seal, refer to Illustration 2.

The root cause of the problem is not understood at this time. When investigating a problem with the brake charging pressure it is recommended that the pressure relief valve is investigated as a potential root cause of the problem before the brake pump is changed.

Report the results of you investigations to one of the people listed below and enter a separate SIMS report for each incident.

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