Axial engine is important for various application like power generation aircraft propulsion. Axial engines like Duke engine requires more than five cylinders. construction is complicated and bulky for small power applications.

Basic idea: In this engine rotation motion is generated on the flywheel which is a crown gear mounted on the rear end of the engine via ball bearing (instead of crankshaft). Reciprocating action of piston is converted to rotation motion of flywheel with the help of quad laterally operated quadlateral yoke slot double action multipurpose scotch yoke actuator.

In this engine combustion chamber is same as that of four stroke engine. It has a compression chamber on the rear portion and scotch yoke operation chamber (SOC)in the middle portion. Flywheel which is crown gear with teeth facing (SOC) is mounted on the rear side of rear compression chamber.

Scotch-Yoke actuator have yoke which is a single rod with longitudinal hole with piston having inwardly opening valves at its rear side and a piston with outwardly opening valve on its front side. This yoke with the help of piston helps to suck and compress the air-fuel mixture and transfer compressed air-fuel mixture from rear compression chamber to combustion chamber via longitudinal hole and valve action.

(SOC) have spur gears mounted on its four sides of external surface which in turn is connected to scotch-yoke actuator pins. These gears are appropriately coupled so that there is no conflict between their actions to rotate scotch-yoke Pins. There are four different configurations in the gears can coupled.

Flywheel gear meshingly engages with teeth of the rear side gears of (SOC).

Reciprocating action of piston causes rotation of pins in quadlateral yoke slot which in turn causes rotation of gears on four sides of (SOC) to rotate which in turn cause of flywheel gear. Flywheel gear is attached to counter weight to cause returning motion of the Scotch-Yoke actuator.

Part of the compression air-fuel mixture happens in cold temperature in the rear compression chamber.