Isolator could be turned on with castell system engaged
The potential for an operator to be injured existed when the mechanical locking system failed on the isolator switch for the mixer castell system. Although the operator had turned and removed the castell keys which should have locked the isolator in the 'Off' position. He discovered when implementing the ‘Try Out’ part of the LOTOTO system, the isolator could be turned back to the ‘On’ position.
An examination revealed that the block the castell key bolt should have engaged with had worked loose and turned 90 degrees. This meant that the bolt was not engaged in the recess of the block, this enabled the isolator to be moved with the keys out. The isolator switch locates on end of shaft. Block should turn with shaft if grub screw is done up correctly. See image