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Action required to prevent unintended movement of mobile crusher tracks
HSE have issued Safety Notice FOD 4 – 2011: Mobile crushing plant – unintended movement of tracks highlighting the potential, on some mobile crushers, for unintended movement of a machine track if an earth/ground fault occurs because of damage to the outer sheath and insulation of the electrical cable that controls the proportional control valve for the track.
This can result in unintended movement of the machine track(s) and the potential for injuries from being struck by or trapped by the machine. Where damage/deterioration of the electrical control cables can lead to a risk of unintended movement HSE state:
The following actions should be taken
The incident occurred on a BL Pegson 1000 Maxtrak cone crusher (year of manufacture 2001), though the risk may be present on any machine with a similar control system.
Owners should contact the manufacturer/ main agent/ supplier of their machine(s) in the first instance to identify if there is a risk of unintended movement of the machine through the electrical control system developing an earth/ground fault.
Where damage or degradation of electrical control cables can lead to a risk of unintended movement, the following measures should be taken to reduce the risk to as low as reasonably practicable:
Install helical sleeving (or similar) to provide additional protection to the control cables and route/secure the cables away from the machine chassis and any other potential rubbing points; and
Consider the installation of fault monitoring to reduce the likelihood of unintended movement should an earth/ground fault occur.
or
Take other appropriate measures.
If improved physical protection is not supplemented by fault monitoring, a system of inspection and maintenance to evaluate and monitor for any damage/degradation to the control circuit, including the electrical cables, will be an essential part of the overall maintenance regime for the machine.
Note: Whilst this safety notice focuses on unintended movement of the plant, it is important that any maintenance or similar work is undertaken following a safe system of work and an appropriate isolation procedure.