DDM Garage Doors

One Spring or Two?

Torsion springs not only have torque, but they are also stretched horizontally along the shaft. As the door opens the spring loses about 7 coils and the ends pull toward each other. Since the spring anchor bracket is anchored to the wall, the winding plug pulls the shaft through the bracket, frequently forcing the cable drum into the end bearing plate. Older style plates were not reinforced, and the supporting horizontal angle would bend as a result, causing the drum to scrape and the cables to peel off the drums.
	One solution for doors that use the flat end bearing plates is to brace the plate with angle iron or wood in a similar manner as pictured. If you have this kind of plate, a brace will usually prevent the drum from scraping the end bearing plate. If you use a single spring with wire that is .273 or larger, however, the extra pull may wear out the bearing. The extra cost of two springs would be justified. On a single car door, however, the spring anchor bracket would need to be mounted above the center of the door to provide space for two springs.
Newer doors often have bearing plates that are anchored to the vertical angle on doors with 12" radius tracks, or secured to the header on doors with 15" radius tracks. This plate was designed to eliminate the problem with drums scraping the plates. It does not, however, prevent the problem of worn bearings with larger wire sizes.
	In addition, to cut costs, many door manufacturers have been using a single spring on double wide 16' steel doors causing disasterous results. If the single spring breaks near the stationary plug, one or both cables often break. If the opener up force is set too strong, it is more likely to wreck the top section or the whole door.
If the spring breaks as the door is closing, or if the door is disengaged from the opener when it is in the open position, the door often slams down like a guillotine endangering life and crinkling the door sections like an accordion.

Conclusion

To protect your door we strongly recommend using two springs if your double-wide door weighs over 150 pounds. Also, if you are converting to longer life springs with wire larger than .250 on a single or double wide door we recommend using two springs rather than one.

When converting from one spring to two on single car doors, the spring anchor bracket needs to be near the center above the door to allow room for a spring on either side of the bracket. If the bracket is offset to one side, relocate it to the center above the door.







In addition, spring brackets normally come with only one bearing or bushing. If you convert from one to two springs, you will not need a second bearing or bushing. Only one bearing inside the center bracket or inside either stationary cone is needed.

You may, however, need longer bolts that secure the stationary cones to the spring anchor bracket. The threaded part of the bolts needs to be 1 1/2". If your bolts are shorter than this, you can pick up longer bolts at any hardware store.

Please feel free to contact us if you have any questions regarding this.