Abstract: A machine for attaching threaded caps to containers continuously moving in a longitudinal path and having endless belts disposed at opposite sides of the caps with the cap engaging belt portions traveling in opposite directions to impart twisting motion to the cap. The belts are moved transversely of the path into and out of engagement with the caps at a uniformed but variable rate to impose two or more pulses of twisting movement to each cap. The times of engagement and disengagement of the belts with the caps, the maximum twisting force and speed of the belts all are under the control of a programmable logic controller.