Overcutter

It is estimated that the capacity of an overcutter is three times that of a chain-breast machine and twice that of a shortwall machine;

The top and bottom portions of the machine are exactly alike and it may consequently be turned over and employed as an overcutter as well as an undercutter.

In addition to its work on longwall faces, the A.B. Fifteen has been adapted for shortwall work either as undercutter or as overcutter, particular care having been taken to give it increased manoauvrability by the provision of special pulleys, and increased mobility by the addition of a tilting underframe.

Deep settlement points revealed that ground losses were concentrated at the overcutter at the front of the shield which had a radius 19 mm greater than the body of the shield to aid in negotiating the short radius turn.