A drive transmission has two counter-rotating cams bearing-mounted within a housing about a rotational axis. The counter-rotating cams have asymmetrical lobe profiles which are operative to drive a corresponding pair of coaxial drive shafts in opposite directions along the rotational axis. The asymmetry of the lobe profiles prevents the cams from locking when the lobe apexes pass the top and bottom dead center positions relative to the follower or drive pins.

An internal combustion engine featuring a radial array of cylinders and pistons; the pistons having rods including cam followers engaging the surface of a cam drive to transfer reciprocating linear motion into rotary motion; wherein between the piston rods and the engine housing are disposed arrays of toothed rollers to provide a rolling interface.

A drive transmission has two counter-rotating cams bearing-mounted within a housing about a rotational axis. The counter-rotating cams have asymmetrical lobe profiles which are operative to drive a corresponding pair of coaxial drive shafts in opposite directions along the rotational axis. The asymmetry of the lobe profiles prevents the cams from locking when the lobe apexes pass the top and bottom dead center positions relative to the follower or drive pins.

A drive transmission, having two counter-rotating cams bearing-mounted within a housing about a rotational axis. The counter-rotating cams have asymmetrical lobe profiles which are operative to drive a corresponding pair of coaxial drive shafts in opposite directions along the rotational axis. The asymmetry of the lobe profiles prevents the cams from locking when the lobe apexes pass the top and bottom dead center positions relative to the follower or drive pins.

A drive transmission, having two counter-rotating cams bearing-mounted within a housing about a rotational axis. The counter-rotating cams have asymmetrical lobe profiles which are operative to drive a corresponding pair of coaxial drive shafts in opposite directions along the rotational axis. The asymmetry of the lobe profiles prevents the cams from locking when the lobe apexes pass the top and bottom dead center positions relative to the follower or drive pins.