Abstract: A power tool (1) has a percussive driving implement for driving an impact tool (8). The driving implement, which may be hydraulic or pneumatic, retracts the impact tool (8) on its return stroke, against the force developed by heavy-duty elastic ropes (24). During the impact stroke the impact tool (8) is urged downwardly by the elastic ropes and, if the tool is upright, by gravity. At the start of the impact stroke the ram (10) is uncoupled by a ball clutch. At the beginning of the return stroke the ball clutch acts to couple the ram once again to the weight (20) and impact tool (8), in order to lift these to the retracted position. The uncoupling of the ram for the impact stroke reduces the loss arising from the resistance of the ram.

Abstract: A power tool (1) has a percussive driving means for driving an impact tool (8). The driving means, which may be hydraulic or pneumatic, retracts the impact tool (8) on its return stroke, against the force developed by heavy-duty elastic ropes (24). During the impact stroke the impact tool (8) is urged downwardly by the elastic ropes and, if the tool is upright, by gravity. At the start of the impact stroke the ram (10) is uncoupled by means of a ball clutch. At the beginning of the return stroke the ball clutch acts to couple the ram once again to the weight (20) and impact tool (8), in order to lift these to the retracted position. It will be appreciated that the uncoupling of the ram for the impact stroke reduces the loss arising from the resistance of the ram.

Abstract: The present invention provides apparatus for applying additional momentum to the movement of a body (1) adapted to reciprocate or flex through a substantially linear or arcuate path, notably for increasing the impact velocity of a linearly travelling weight upon an object (3), which apparatus comprises means (4) for retracting the body from its rest position, notably for retracting a weight from the point of impact between the weight and an object located at the rest position of the weight, means (5) for biassing the body towards its rest position, notably for urging the weight towards the object so as to impart additional impact velocity to the weight as it travels towards the object, characterised in that: a) the means for biassing the body towards its rest position is an elastic polymeric material which is retained under tension or compression when the body is in its rest position; and b) the biassing means is one which undergoes strain crystallisation.

Abstract: Apparatus for applying additional momentum to the movement of a body adapted to reciprocate or flex through a substantially linear or arcuate path, notably of increasing the impact velocity of a linearly travelling weight upon an object. The apparatus includes an element for retracting the body from its rest position, notably for retracting a weight from the point of impact between the weight and an object located at the rest position of the weight and an element for biasing the body towards its rest position, notably for urging the weight towards the object so as to impart additional impact velocity to the weight as it travels toward the object. The apparatus is characterized in that: a) the element for biasing the body towards its rest position is an elastic polymeric material which is retained under tension or compression when the body is in its rest position; and b) the biasing element is one which undergoes strain crystallization. Also a method for breaking or penetrating a surface using the apparatus.