Introduction to Sectional Garage Door Extension Springs

Sectional garage doors are hinged, and they bend in the tracks as the door opens and closes. Many of these doors are counterbalanced with extension springs, also designated "stretch springs," and they have seven characteristics. The length is the measurement of all the coils pressed together. This, along with the inside diameter of the coils and wire size - the thickness of the wire from which the springs are made - determine the stretch, the distance the spring is extended - normally half the door height, and pull, the force the spring pulls when stretched its normal length. The type of ends determine how the ends of the spring are mounted. The initial tension is the percentage of pull needed to separate the coils. This is determined by the pitch with which the springs are wound. On sectional garage door springs, this normally is 15 percent. For example, a 100-pound pull spring requires 15 pounds of weight to separate the coils; when a door is open, the two springs will support 15 pounds of door weight without any stretch.

Most extension springs are made of oil tempered wire. These are normally coated or painted. Some springs are made of galvanized wire.

Garage door extension springs counterbalance the weight of garage doors to make them easy to open and close. One end is secured to a stationary angle or bracket, and the weight of the door pulls the other end.

• Engineered For Maximum Application Range.
• Minimum 10,000 Cycles, At +/- 7.5lbs Of Target Door Weight.
• Plug-end extension spring with safety containment rod
• For use with single-panel garage doors, toy hauler doors, etc.
• Black Coated, Oil Tempered Wire Provides A Clean Durable Finish.
• Clear, Easy To Read Spring Markings For Easy Identification.
• Weigh door by disconnecting springs and placing scale under door
• Match measured door weight with same spring weight capacity
• Double-looped ends for stronger connection to lift cables