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 rotary cam radial engine formed of two primary components engaged at a mid section to allow for an easy repair to the vehicle. The device features a body having radially oriented apertures; and a plurality of pistons in a respective reciprocating engagement, within each respective said cylinder. The pistons are driven by low pressure fluids and/or a vacuum and the engine being formed of two main components can be taken apart without tools for maintenance and reconfiguration.