Abstract: Pump or motor comprising at least one cylinder housing being closed at both ends and a piston body received in said housing so that at both ends of said housing a working compartment is formed, the piston body being provided with a cavity shaped such that in it one piston rod can be received, one end of which is connected to the piston body and the other end to a crankshaft which pass through the piston body.

Abstract: A rotary piston machine comprising a housing, a central shaft fixedly connected to said housing, a cylinder mounted in said housing for rotation about said shaft, a cam on said shaft, a piston mounted within said cylinder, said piston having a recess functioning as a camming track co-operating with said cam for axially moving the piston in the cylinder upon rotation of said cylinder in the housing, said housing and said cylinder each having at least one fluid inlet and at least one fluid outlet. If the machine is formed as an internal combustion engine, the cylinder comprises at least one combustion space connectable to said fluid inlet and said fluid outlet and to ignition means.