| http://www.w3.org/ns/prov#value | - The linear electric motor constituted by the stator 125 and the drill shaft 122, can be operated so as to power both the forward and return strokes of the drill bit 106 by appropriate change of the phase sequence of the electrical supply, or alternatively, the motor could operate to effect only one of the strokes, for example the return stroke, the other stroke being then effected by release of en
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