the stroke limiter 36 limit switch 38 stop 40 and proximity switch 42 are supported for adjustment to be locked in the adjusted position by providing either conventional elongated slot arrangements or threads with lock nuts this adjustment provides that the proximity switch 42 will emit a signal at the exact moment when the hooks 8 and teeth 16 are in alignment with each other so that the magnetic clutch 26 is energized at the proper time with this arrangement it is possible to insure that the movement of the longitudinal conveyor 1 and movement of the weft thread carriage 35 are maintained in rigid synchronization with the central machine drive the axial adjustment of the stroke limiter 36 thus determines the exact length of the racking movement and thereby permits adjustment of the width of the array of weft threads the adjustability of the limit switch 38 and the stop 40 determines the exact starting position of the rake 2 the reason for continuing to move the rake 2 by means of the cylinder 29 after reaching the limit switch 38 until it hits the stop 40 is that it is not possible to exactly define the starting position by means of the magnetic clutch 26 discontinuing rotation of the sprocket wheel by means of the limit switch 38 however a definite starting position is accurately defined when the carriage bracket 20 engages the stop 40 for.