Swashplate Engine

Swashplate Engine

Axial engines, including barrel engines, swashplate engines and cam engines, are a type of reciprocating engine with pistons arranged around an output shaft with their axes parallel to the shaft.

The key advantage of the axial design is that the cylinders are arranged in parallel around the output shaft rather than at 90 degrees as in crankshaft engines. As a result it is a very compact, cylindrical engine, allowing variation in compression ratio of the engine while running. In a swashplate engine the piston rods stay parallel with the shaft, and piston side-forces that cause excessive wear can be eliminated almost completely. The small-end bearing of a traditional connecting rod, one of the most problematic bearings in a traditional engine, is eliminated. An alternate design, the Rand cam engine, replaces the plate with a sine-shaped cam.

A wobble-plate is similar to a swashplate, in that the pistons press down on the plate in sequence, forcing it to nutate around its center. This motion can be simulated by placing a Compact Disc on a ball bearing at its centre and pressing down at progressive places around its circumference. The difference is that while a wobble plate nutates, a swash-plate rotates.