Disclosed and taught is a novel drive mechanism for a cyclic operating tool employing an energized flywheel to provide the necessary energy to perform a working cycle. The drive mechanism disclosed is particularly useful in hand tool applications such as a hand held nailing machine. The flywheel may be energized by a corded or battery powered motor. The herein disclosed mechanism teaches a novel pair of ball ramp cam plates wherein a first pair of ball ramps cause an initial engagement of a clutch with the energized flywheel whereupon rotation of the clutch causes activation of a second pair of ball ramps which affect compression of a spring which acts to increase the pressure applied to the clutch thereby assuring a slip free engagement between the clutch and he flywheel throughout the working cycle of the drive mechanism. Upon completion of the drive mechanisms working cycle, the second pair of ball ramp cam plates further act to disengage the clutch from the flywheel whereby the flywheel may dissipate the unused kinetic energy remaining within the flywheel as the drive mechanism returns to the start position.