Engine usable as a power source or pump

An engine including,

• a rotor mounted relative to an output shaft, the rotor having one or more piston cylinder assembly's disposed in or on the rotor with the longitudinal axis/axes of the one or more piston cylinder assembly's orientated to be tangential to a peripheral rim of the rotor, the rotor or output shaft having a lobed cam which rotates at the same, greater, or slower speed than the rotor,
• each said piston cylinder assembly having a piston connected to a distal end of a lever member mounted relative to the rotor at a fulcrum or rocking point which is offset from an axis of the rotor and output shaft, the lever member at a proximal end bears on the lobed cam,
• wherein the lobed cam has a cam surface which is tapered in side elevation, so that axial movement of the lobed cam allows the point of contact of the proximal end to the cam surface to be varied to thereby alter the stroke length up or down as required, and
• wherein via combustion, each piston moves within its cylinder to rotate the rotor continuously relative to a not necessarily stationary part of the engine.