PURPOSE: To stop a driven side at the optional position by cancelling a reciprocating motion of a driving side, by actuating the driven side in a direction opposite to the driving side, in a driving slider, reciprocating along both the upper and lower surfaces of a base bed, and a driven slider.

CONSTITUTION: A driving slider 6 and a driven slider 16 are respectively installed in a freely slidable state along both the end surfaces of a base bed 1. Then a sector gear 22 and a rack 18 are installed between both the sliders 6 and 16 to make an interlocking between both the sliders possible through an engagement of the gear 22 and the rack 18. On the other hand, a pair of cam followers 24a and 24b are mounted rotatably to the sector 22 to be engaged with both a straight cam surface 25a and an inclined cam groove 25b. Further, when the cam follower 24b at one side enters the groove 25b to give a turning action to the gear 22, the slider 16 is actuated in a direction opposite to a sliding direction of the slider 6 to cancel a reciprocating motion of the slider 6, and then the stroke of the driven side is optionally controlled when the stroke of the driving side is constant.