Abstract: A mechanism for translating rotation motion to linear motion utilizing a turret rotatable about a first axis carrying a crank shaft rotatable about a second axis parallel to but offset from the turret axis and carrying a crank arm which in turn carries a drive element having a third axis parallel to but offset from the first and second axes, the drive element contacting and driving a driven element guided for movement along a generally linear path upon the rotation of the turret between first and second generally diametrically opposite positions relative to the arc of rotation of the turret, a pair of cooperative abutment members for absorbing the momentum of a load driven by the driven element, one of the abutment members being carried by the turret and gearing meshingly interconnecting another of the abutment members and the crank shaft, the one abutment member being effective to contact and move the other abutment member upon the driving element moving contiguous the first and second positions, and a sprin