Abstract: A power transfer mechanism for transferring power between rotating components and reciprocating components includes a cam rotatable about an axis and having an odd number of lobes evenly spaced therearound, and a double acting reciprocating member which includes two diametrically opposed pistons, each of which is connected rigidly to a roller follower in operable relationship with the cam, and connecting means disposed between the pistons for resiliently urging the roller followers against the cam.