V O Design and Innovation Limited

Vagn-Erik Dall

Peter Lawes

David John Reed

A tool for breaking a shaft includes two aligned tubular elements (), each having an end portion for receiving a contiguous length of the same shaft (). Means are provided for locking each end portion against rotation relative to the shaft length received therein, and the elements are adapted for rotation relative to one another with the end portions so locked, to relatively twist the shaft lengths and shear the lengths at the interface between them. The element end portions will normally have juxtaposed faces, and it is preferred that the faces are moved towards each other during the relative rotation and as the shaft lengths are twisted relative to each other. This assists in achieving a substantially planar face at the fracture plane. A compressible washer may be disposed between the juxtaposed faces. This can stabilize the moving parts as the shaft is broken, although normally screw threads on the tubular elements will effect the movement of the element. towards each other, and this in itself may provide sufficient stability.

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Vagn-Erik Dall