Pusher springs create a downward acting force against the top section of your garage door to prevent cables from slipping off the drums. They are most often required when jackshaft side mount openers are installed on standard lift doors which lack a natural downward acting force. 1. What are pusher springs used for? The main purpose of spring pusher installation is to assist in maintaining constant cable tension when the door is starting the down cycle. This is especially the case on standard lift doors that lack a downward acting force achieved with high lift or full vertical lift doors. When an opener starts running with the door in the open position there is a tendency for the door to initially jump - causing cables to be thrown of the drums. Jack shaft operators installed on standard lift doors are especially prone to cables being thrown off the drums because they lack a natural downward acting force. Another secondary benefit of pusher springs is the prevention of the door flying off the back end of the horizontal tracks in the event of user or operator error. This is especially the case on manually opened and closed doors where the user might fling the door open with excessive force. This problem is quite common in loading dock bays and storage facilities where people fling the door upward as fast as they can. Although track bolts are fastened to the ends of the horizontal track to stop door travel, pusher springs do a much better job stopping door travel. 2. Do I Need Pusher Springs or Track Bumpers? Pusher springs are often called plungers or bumpers, but shouldnt be confused with a different part called a leaf bumper. As the name implies, pusher springs are spring loaded and leaf bumpers are not. As the garage door travels towards the end of horizontal track the top section compresses against the pusher spring. Then when the door starts downward travel the pusher springs unloads the compression force against the top panel, avoiding the sudden jump at the start of door travel. This push force is usually enough to keep the cables from slipping over the grooves of the drum. If you are looking for an aid to keep your garage door cables from jumping off the cable spools pusher springs are needed. If you are looking to keep your garage door from slamming into the track bolts at the end of the horizontal tracks leaf stylebumpers are needed. Pusher springs are installed at the back of the horizontal tracks compressing against the top section as the door opens. When the door starts closing that tension is slowly released to prevent the sudden jump start that causes cables to slip off the drums. Pusher springs are often referred to by other names such as plungers, bumpers, stoppers and pushers.