Mechanism to control the movements of weft insertion members in shuttleless weaving looms

In a mechanism to control the movements of weft insertion members in the shed of shuttleless weaving looms of the type wherein a gearwheel controlling a gripper carrying strap is caused to rotate forward and backward by a variable pitch cam screw passing longitudinally through a slider which moves forward and backward along a rectilinear path;

• the improvement in which said slider carries means for engaging the thread of said screw and adapted to cause the rotation thereof, comprising opposed pairs of sliding blocks engaging opposite sides of the thread of the screw, and means mounting the blocks for oscillating movement about axes inclined at opposite acute angles to an axis perpendicular to the axis of the screw.