Failure analysis of solenoid valve components from a hydraulic roof support

摘要

In modern mining practice the use of hydraulic roof supports is common, allowing mined faces to advance or retreat quickly with significant benefits to productivity.These units vary considerably in size but the fundamentals of operation are essentially the same. A high pressure hydraulic fluid is pumped into hydraulic cylinders, controlled by valves. Solenoid valves control the flow of pilot pressure to spool valves that, in turn, control the power lower and power raise functions of the supports.Following an incident when a roof support powered down unexpectedly resulting in fatal crush injuries to a miner, an investigation was carried out to establish the cause. The investigation considered both control system and mechanical failures. Early work focussed on the potential failure of the power lower solenoid valve and the possibility that the valve could have passed hydraulic fluid when in the de-energised position.