|
There are two kinds of garage door springs -- torsion springs and extension springs. Torsion springs are the kind wound-up on a rod above the garage door opening. There are a pair of them--one on each side of the center of the door. When one breaks the other often follows, so have both replaced when one breaks. Hire a professional.
Torsion springs are devices that lift most of the weight of a garage door so that the door can be opened manually or by an electric opener. The torsion principle is applied via an efficient and economical apparatus consisting of a torsion shaft under spring torsion, which turns lift drums, which wind cables attached to the door near the bottom. All of this apparatus is mounted over the top of the door. The energy stored is very powerful.
The most common grade of torsion springs have an expected life of about 10,000 cycles. The hardened and tempered steel experiences tremendous forces each time the door opens or closes. If you average about two car trips per day, opening and closing the door a total of 4 times daily when you come and go, then that expected life becomes 2500 days, or only about 7 years. Gradually, the steel fatigues with each flexure, and eventually cracks and breaks, usually releasing its stored energy in an instant. If you have an automatic opener, you probably tend to cycle the door even more frequently, and can expect the need for spring replacement even sooner.
|
|
The other kind of springs - the kind that run along the upper, right and left door tracks, and extend/stretch to do their job, called extension springs -- are not as difficult a home repair. However, some safety measures are in order. Remember, when these springs are extended (door down) they are stretched to potentially deadly force--they may be lifting a 400 pound door. Extension springs are also used for trampoline springs.
Garage door extension springs are designed to accommodate easier garage door lifting. A typical size is 25" X 42" springs for 7 foot doors (25 inches in length, detached (relaxed). Springs can be ganged for heavier doors. Extension spring containment cables are avaiable and recommended (required in California). Quality springs resist rust and moisture, and are made of heavy gauge material for strength, durability and easy installation. They go up to 84 inches of overall length when stretched.
Higher capacity metal springs are available for 14' doors and doors weighing 400 lbs.
Extension springs have a design that helps them to wound to resist the extension and provide the return force to devices with extended positions so that they come back to their original position. These springs have hooks, eyes or other such shapes at the ends to connect to the components that they attach to.
Their use is mainly to provide the return force to the components that extend from their original position. When you search for extension springs the important parameters you need to keep in mind while searching for them are outer diameter, wire diameter and free length. You need to consider the design units too. Design units can be specified in English or metric units. Spring parameters that are important to consider when searching for trampoline springs springs include the maximum load, the spring rate, and the extended length. The spring rate is the force per unit spring deflection. The length experienced at full extension is extended length. The maximum load is the load experienced at full extension.
|
|
|
|