Abstract: A variable feed drive mechanism comprises a novel linkage for delivering an adjustable amount of motion from a reciprocating drive lever to a unidirectional clutch output mechanism. A first linking member is pivotally joined to the distal end of the reciprocating lever and disposed substantially perpendicular thereto. An adjustment lever is joined at one end to a fixed pivot, and a second linking member is pivotally joined at one end to a distal portion of the adjustment lever, and at the other end to the distal end of the first linking member. A third linking member is pivotally joined at one end to an arm extending from the ratchet-clutch mechanism, and is pivotally joined at the other end to the junction of the first and second linking members.