Usually, the largest mechanical thing around your house is the overhead garage door - the one you're driving your car through, sometimes without even opening it - I know that you do :-).
The major, and the most dangerous componnent of the overhead door is the garage door spring - (or springs depending on the design), which supports the entire weight of the door panels (sometimes over 400 pounds) and helps you to lift / lower the entire door assembly. I have personally installed 3 overhead garage doors with 2 different types of springs, and you do have to trust me on that - garage door springs are under enormous pressure and you can get seriously injured or even killed when performing such work. If you decide to take your chances - it is imperative that you follow instructions to the last detail! Even if you have a friend or a professional doing it for you, read it and check everything after the installer finishes the job. The garage overhead doors have no safety brakes (at least I haven't heard about any), that would prevent it from falling down when the supporting spring fails. I've found some US patents for such devices, but apparently none of them were ever implemented into an actual garage door.
According to the US Consumer Product Safety Commission, garage overhead door related accidents account for thousands of injuries every year (average of 30000 per year). For example, these injuries are: fractures, crushings and amputations. It is believed that not all injuries are reported in the United States . (CPSC)
There are basically two types of the garage door spring systems utilizing tracks / side rails (at least these are the most common types in Illinois and probably the rest of US):
1. garage door torsion spring(s) which are wound-up on a rod above the garage door opening top section ( door header)
2. garage door extension springs that are attached on either side of the door and stretch along the horizontal part of the track when the door is closed
You might also have an old, one piece door that swings outward as it goes up and overhead. This particular design will have springs mounted on the sides of the door opening - at about your waist height, secured to a lever bracket system that extends the springs toward the ceiling at the door closing. It is an old and extremely dangerous system, not manufactured anymore. If you have such a system in the garage, I'd highly recommend replacing it.
Garage door torsion springs - there are either single or double spring designs. The spring will usually break while under the maximum stress which is when the overhead garage door closes / travels down, or it is already completely closed (USUALLY). If you're closing it manually and it happens during this operation, don't try to prevent it from crushing down, let it go ... well, unless your foot is where the door will slam!
When one of the two garage door springs breaks you need to have them both replaced at the same time! It will cost some extra money, but having an old and new spring installed will:
- put much more stress on the new one
- the door will loose proper balance
- the remaining old garage door spring will most likely break soon
Torsion springs for residential overhead garage doors have anywhere between 5000 - 30000 cycles life span. Those digits represent an average total number of times you should be able to open and close your door before anticipating garage door spring replacement.
Garage door extension springs - you might have either one or two on each side of your overhead garage door A critical issue with those springs is to have a safety cable installed inside of each single spring and secured properly, so when the door opens and closes, the spring can freely slide on this cable! When the garage door spring snaps without the cable inside, broken ends might severely injure anyone standing within their range. The cables should be always included with the overhead garage doors hardware (assuming that they came equipped with extension springs), but A LOT OF PEOPLE either forget to install them, or don't read instructions and maybe assume that they are not required. Unlike the torsion spring, which doesn't really show any visual wear until it breaks, extension spring wear is much easier to spot, because they simply change dimensions: the coils are over-stretched (best visible when the garage door is open). If you notice such a behavior on your garage door springs - it's time for a replacement.
And for both types of the garage door springs - their tension should be evenly adjusted (on a two spring system) so the overhead door travels properly in its tracks - to test it, stop the door slightly above the garage floor (1" or two) and make sure that its bottom / top edge are perfectly horizontal. Measuring the gap along the bottom might not be the best way to confirm that, because the garage floors are often out of level. Placing a level somewhere in the center section of the garage door top edge would give you the best readout (remember that the door should not be closed completely!). When the springs are properly adjusted, you should be able to raise and stop the garage door at any height, and it should stay at this level without any assistance ( garage door opener arm disconnected).
Important things to remember:
1. Check the rollers / hinges, cables, and the overhead garage door springs often to ensure they are in good working condition
2. Educate your children about garage door safety
3. Never leave children and disabled persons unattended near or in a garage door path
4. Keep your body clear of the door path when closing
5. Don't leave a personal property underneath an open garage door
6. Read more about the garage door opener and other garage components
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