Disclosed are crankshaft, single-plate cam and beam mechanisms that provide significant improvements in performance for 2 & 4-stroke engines, compressors and pumps. These cost effective mechanisms include linkages with the new and improved use of pivoting arms that operate with a variety of cylinder arrangements. One embodiment of the crankshaft mechanism has its crankpin roller positioned within a novel yoke-arm. The cam mechanism uses a pair of centrally positioned parallel links that are connected to roller cam followers and single or diametrically-opposed pistons. A pair of laterally extending follower arms connects to the ends of the links to provide support and alignment for the piston rods. Between the reciprocating links, cam followers and follower arms is a rotating odd-lobe plate cam. A beam mechanism uses opposite-direction extending balancing beams that are connected to links, cam followers and piston rods.