Abstract: The invention provides a press action machine having a body which supports an operative element and means mounting the operative element for simple linear reciprocatory movement, the body itself being in the form of a curvilinear loop such as a circle or ellipse, and the arrangement of the operative element being such that the direction of its linear reciprocatory motion is parallel with a diameter of the body.Since there may be more than one operative element, the arrangement is preferably such that the reaction to the vector addition of the operative forces is substantially on a diameter of the body.Arrangements are described in which there are reinforcing struts arranged chordally of the body loop and in one arrangement, the body comprises a plurality of concentric loops. In another arrangement, the body comprises a series of loops secured together end-to-end.