(under subclass 124) Device wherein the means to drive the tool includes first and second rotatable members, each of which has a generally uniform surface of revolution, wherein the first member is supplied with rotary effort and the second member is connected to the tool, the two members being adapted to engage each other at a portion of their respective surfaces of revolution to transmit rotary effort from the first to the second (and thereby to the tool) in proportion with the pressure applied to force the surfaces into engagement with each other.
