Slide 1 reciprocates along fixed guides b-b and carries a cam consisting of block A, arm B and bar C which imparts reciprocating motion to slide 2 a long fixed guides d-d in a direction perpendicular to the travel of slide 1. Slide 2 has alternating long and short strokes with dwells at both ends of each stroke while roller 3 of slide 2 rolls along block A and bar C of the cam. Bar C is maintained in its horizontal position on both the long and short strokes of slide 2 by means of link 4 which, together with arm B and bar C, forms a parallelogram. The stroke of slide 2 is changed every other stroke by changing the angular position of arm B. For this purpose, star-wheel 6 is turned by pawl 5 through an angle of 90° on each stroke of slide 1 to the right. Star-wheel 6 is rigidly attached to rectangular block 7 which it turns freely on axis E of slide 1. Lug e of arm B rests consecutively on the slides of block 7 and is held in contact with the block by spring 8. Each time star-wheel 6 is turned, block 7 turns arm B which then bears against a different slide of the block.
$3232$CmL,LL$