In operation, cartons pass over belt-driven cam rollers. A metered restriction in the N740A valve body limits the depletion of the air bag. The spring tensioner reactivates the valve before the drive disengages, and replenishes the bag.
When the carton stops on the cam roller, the Humphrey N740A valve is held open long enough to exhaust the air bag. This disengages the drive belt from the rollers, and creates a cascade effect along the entire conveyor line.