One of these "sproing" events at our house finally motivated me to research how these repairs are done. This happened in 2002, when my wife parked the chariot and shut the door. After the door closed, there was a horrific noise that she could only astutely describe as, "a big spring snapping and vibrating". Although I have hired professionals several times in the past to install or repair garage doors, the difference this time was the innovation of Google and newsgroups like alt.home.repair. I was determined to learn the process and to search for online parts vendors.
If this manipulative, we-are-your-nanny business approach is truly in our best interests as consumers, then we shouldn't be allowed near ladders, lawn mowers, or power tools. Those products are just as hazardous and prone to misuse as torsion springs, yet no one thinks of them as forbidden. The only genuine difference is that torsion springs are a hazardous thing you need only rarely, while a lawn mower is a hazardous thing you need all the time.
The Heavy Duty Chain Extension Kit for 10 The Heavy Duty Chain Extension Kit for 10 ft. High Garage Doors is required for reliable everyday operation of Chamberlain heavy duty chain drive models in 10 ft. garage door applications. Featuring a quick-install extension rail and replacement chain the kit includes everything needed for quick and easy installation. Includes ... More + Product Details Close
The deluxe-model upsell trick: Don't you want the best? Don't you want to protect your family? Galvanized springs may be offered to you at extra expense as "longer lasting". Although bare springs (also called "oil tempered") can develop a light film of rust, the eventual failure is due to fatigue and not corrosion. The use of coated springs (whether galvanized, painted, powder-coated, or surface-converted) is mostly about appearance: the customer likes his new door to look shiny, and the customer doesn't like repair parts that show superficial rust from storage.
The typical electric garage door opener consists of a power unit that contains the electric motor. The power unit attaches to a track. A trolley connected to an arm that attaches to the top of the garage door slides back and forth on the track, thus opening and closing the garage door. The trolley is pulled along the track by a chain, belt, or screw that turns when the motor is operated. A quick-release mechanism is attached to the trolley to allow the garage door to be disconnected from the opener for manual operation during a power failure or in case of emergency. Limit switches on the power unit control the distance the garage door opens and closes once the motor receives a signal from the remote control or wall push button to operate the door.
Two of the spring references specifically for the garage-door industry are the APCO Spring Manual by Bill Eichenberger, and the Torsion Spring Rate Book by Clarence Veigel; these give tables of spring sizes and torque constants. Spring engineering principles in general are described in the Handbook of Spring Design published by the Spring Manufacturer's Institute; the formulas allow you to calculate torque constants knowing only the geometry and the Young's modulus of the material. You can also find some brief spring information in standard references like Machinery's Handbook and Marks' Standard Handbook for Mechanical Engineers.