(under subclass 368) Apparatus including relatively rotatable screw and follower (e.g., nut) elements, the follower engaging the thread of the screw, and the elements being also bodily displaceable as a unit (either axially or rotatably); the input signal means, the valve means and the working member being operatively connected to the elements such that the signal input means will cause operation of the valve means to initiate movement of the working member by moving a first one of the elements either by bodily displacement or rotation relative to the second element while the working member remains stationary; the operation of the valve means causing movement of the working member which will cause the second element to move by the other type of movement than that caused by the input signal means to cause operation of the valve means to stop movement of the working member while the input signal means remains stationary.
(1) Note. The screw element of the above definition is intended to be limited to an element having a helical track of more than 360 deg. and is by this characteristic distinguished from a cam device as provided for in subclass 382.
