Drive arrangement to produce a rotary or turning motion by means of a fluid or gaseous pressure medium

Claim 1

A drive arrangement for executing a rotary or swivel motion by means of a liquid or gaseous pressure medium, comprising: a housing; a working shaft mounted in said housing; an eccentric part operatively connected to said shaft; at least one inflatable expansion cell mounted between the internal wall of said housing and said eccentric part along the outer surface of said eccentric part; and being operatively connected thereto; and input and output means connected at a single location to said cell for feeding and exhausting pressure medium to and from said cell in a predetermined sequence; wherein said expansion cell is in the form of a freely inflatable cell attached to said input means in a small area with respect to the total surface area of said cell such that during a change in volume of said cell, said cell squeezes and the difference between the circumference of said eccentric part and the interior of said housing is at least partially taken up by the squeezing of said expansion cell and wherein in the minimum volumne phase of the sequence, the periphery of said eccentric part confronts the surface of the internal wall of said housing forming substantially similar surfaces so that a maximum area in a tangential position of said expansion cell contacts said eccentric part or the internal wall of said housing; whereby when said expansion cell expands, said eccentric part moves away from said housing and said expansion cell exerts a rotational moment on said eccentric part, a force that is directed along the central axis thereof and therefore along said working shaft.