A power cam drive assembly for generating and delivering two different degrees of force serially to a body, the second force being greater than the first force. A main drive gear is coupled to a driven cam gear which is coupled to an outer cam shell. A cam core is nested within the cam shell for rotation along an eccentric path therewithin. The cam core has an axial extension also coupled to the driven cam gear. A windable clock spring located between the cam core and cam shell has one end secured to the cam core and the other end locked to the cam shell. A cam roller is disposed within the cam core. The clock spring has a greater rotational torque than required to rotate the cam core. The driven cam gear rotates, causing the cam shell to rotate, through the clock spring interconnection, causing rotaton of the cam core with attendant rotation of the cam roller which impacts on a cam stop in its path preventing further rotation of roller and cam core, causing the first force to be transmitted via a lever arranged to transmit the first force to the body. Further rotation of the cam shell causes the cam roller to move in a downward direction, winding the clock spring, resulting in further rotation of the cam core producing the second downward force for transmission to the body via the lever.