Garage door torsion springs are secured to a metal tube or shaft in the header area of the garage door. Torsion springs have a 1-inch hole which allows a tube or solid shaft to pass through. For setups where the shaft passes through the inside of the spring, the spring can be mounted on the end of the tube or in the middle using a center bearing plate. Torsion springs have a cone at each end called stationary and winding cones. Stationary cones secure the spring to the center bearing plate. Since this plate is secured to the wall, the stationary cone doesn’t move, but it can be bolted through the center bracket to another spring. Winding cones are at the outside end of the spring line assembly. These cones are used to apply tension to the spring system through a series of winds or turns during installation or repair. Torsion springs are wound up in a standard lift door and down for doors with low headroom requirements.
Garage door torsion springs are turned with torque being applied between the shaft and the center bearing plate. This tension is filtered to the drums, cables and bottom brackets to lift your garage door. Torsion springs depend on balance to function properly. Each spring or 2-spring system is calibrated to match the weight and size of your garage door. Failing to use the correctly calibrated springs will cause serious problems with a garage door including personal injury. Springs unwind as a garage door opens and load as the garage door closes. This loading process takes the majority of the lifting load so your operator can do the rest.
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Properties of Garage Door Torsion Springs
Torsion spring setups have three distinct characteristics that help identify their application. These characteristics determine the lifting power and number of cycles the spring will have.
- Wire Size (gauge)
- Inside Diameter (I.D.)
- Length (inches)
- Right or Left Wound?
- One or Two Springs?
Wire size can be easily measured by a spring gauge tool. The wire size, known as gauge, is simply the thickness of one coil. If you don’t have a spring gauge tool there is no need to worry – you simply need to count the length of 20 coils on the spring. Lay a small tap measure flat on top of the spring, putting the flanged end of the tape down between coils to hold it in place. Count 20-coils and take not of the length. The length of 20-coils is used in a formula to calculate the gauge of the spring. Spring companies like Service Spring have handy charts to input that type of data.
The inside diameter (I.D.) is a measurement of the width of spring on the inside of the coil. Again use a tape measure to measure the width of the hollow part of the spring – from inside edge to inside edge. Do no confuse this with outside diameter which takes into account the coil width as well. Inside diameters or I.D’s vary by spring manufacturer and the company that installs them. The most common residential spring inside diameters are 1.75 and 2-inch I.D. However some residential springs can go up to 2.5 inches in inside diameter. Commercial springs used on larger doors can go up to 6-inches in inside diameter or more.
The length of the spring is usually measured in inches, including all of the coil, but not the end cones on each side. When measuring springs for replacement be sure not to measure the spring while it is still wound on the tube as this will add about 3-6 inches to the length due to the torque applied to it. If you are measuring a broken spring you will obviously need to piece together the broken end as well.
Unlike extension springs, torsion springs are either right or left wound. From the inside of your garage looking out (ISLO) a spring on the right side of the center bearing plate is left wound. A spring on the left side of the center bearing plate is actually right wound. You may also hold the spring upright with the end of the coil facing you. If the end of the coil points left it is left wound, if it points to the right it is right wound.
These three factors (length, gauge, inside diameter) determine the lifting power, which determines what size and weight of door the springs can be applied to. Larger wire sizes (gauges) are stronger and used on heavier doors and commercial applications. Springs with larger inside diameters are used on commercial applications as well. Residential doors generally have 1 3/4″ , 2″ and 2 5/8″ inside diameters. Commercial sized springs are usually 2 5/8″ , 3 3/4″ and 6″ inside diameters.
Note: If you are ever in need of a torsion replacement spring you will need to identify those four characteristics in order to purchase a new one (Inside Diameter, Length, Wire Size, Side). You can also measure the weight of your garage door using a bathroom scale or identify the size and model of door you have and consult the manufacturer.
One Spring or Two Springs?
Residential single car garage door applications generally use a single torsion spring. Double car doors or heavy residential doors will utilize a dual spring setup for more lift and balance. Two spring setups are generally much safer – if one spring breaks when the door is open the other spring should be able to stabilize the door until a repair is made. Dual spring setups are more expensive, but last longer and help the door operate smoothly by balancing the tension and torque.
What Lifts the Garage Door?
While it is true that an opener both opens and closes a garage door, it is the spring system that does the majority of the work. Most openers don’t have enough horsepower to lift a garage door without the help of springs under tension. Even if garage door openers could open and close your door without springs, they certainly wouldn’t last long doing such heavy lifting. Properly calibrated and installed torsion springs will help the longevity of a garage door opener. They will also allow a user to open and close their garage door manually with ease. Springs are under the most tension when garage doors are fully closed and therefore have the most lifting power at that point. As the door opens the spring unwind and gradually lose power as the door goes up the track and around the radius. Torsion spring systems use gravity to load the springs on the way down. This unique loading and unloading of force helps near 95% of a garage door’s weight be lifted by the springs alone.
Each garage door manufacturer uses different types and sizes of springs for door installation. Some companies use 1.75-inch inside diameter springs, while other companies use 2-inch I.D. springs. Regardless of what type of springs you have, computer programs are available to convert from one spring to another. This is why it is so important that you have the gauge, length and inside diameter measurements available when attempting to purchase a new spring.