One of the staples of modern life in the suburbs and country-side is the garage door that you open and close multiple times throughout a given week. Modern garage doors make the process of operating them a fairly easy one by using some simple machinery to assist with the process of opening and closing the door. If you have ever wondered how garage door works then here's a quick primer on the machinery that makes the process of getting your car in and out of your garage a simple one.

How Garage Door Works

There are two basic types of systems that assist in taking the weight off the garage door to help you to open it. Each system acts as a type of counter-balance which stores energy in a spring as the door is closing and releases that energy as the door is opening.

Garage Door Functioning

As the door is closing it switches from a supported horizontal alignment to an unsupported vertical alignment which means that the weight of the door and the corresponding force required to stop it from closing too fast increase. As the door is opening the force required to lift it is high when the door is mostly vertical and lower when most of the door is in the horizontal alignment. By storing the energy that is required to lift the door in a spring when the door is being closed and using that energy to help assist in lifting the door when it is being opened it is possible to even out the force required to open and close the door. This makes opening and closing the door far more manageable for both a person manually opening the door and the motor in a motorized door-opener system. For heavier doors it would be near impossible for the average person to open the door or close it safely without the springs balancing the load.

The two main spring systems used with a garage door are:

1. The Torsion Spring Garage Door System

This system uses torsion springs that store the energy required to open the door in the rotational torque of the springs. The two springs are mounted on a rotating shaft that sits horizontally above the door opening with one end of each spring allowed to turn with the shaft and the other end being anchored to the door frame at the middle of the shaft. As the door is closed the closing door pulls on a cable wound onto a reel on the shaft which causes the shaft to rotate and turn the torsion springs. This winds the springs and stores the energy from the closing door in the spring as a result. When the door is opened the opposite process occurs with the energy bound up in the springs being used to assist in opening the door.

The torsion spring system is the most common system found on modern garage doors. It is more robust and has fewer exposed parts than the extension spring system so it lasts longer and is safer to use. It tends to be more expensive than the other system in the short term, but will likely end up costing you less over the longer term as it tends to cause fewer problems.

2. The Extension Spring Garage Door System

This system uses springs which expand to absorb the energy from closing the door and contract to release that energy when it is required to assist in opening the door. One end of the spring is attached to the bottom of the door via a cable running on a system of pulleys with the other end of the spring anchored to the door opening framework. When the door is closed the bottom of the door pulls the cable and expands the spring. When the door is opened the spring is allowed to retract and assist with the opening of the door by pulling in the cable that runs from the spring to the bottom of the door.

The extension spring system tends to be cheaper than the torsion system, but the springs and cables will last a fraction of the time and it has more exposed parts which may become a hazard.

For safety, this system usually has a retaining cable running through the middle of the spring that is designed to stop pieces of the spring from flying free if the spring breaks. If you find that your garage door doesn't have these cables inside the springs then you should get them installed by professionals, as this can be very dangerous.

Converting an Extension Spring System to a Torsion Spring System

If you have an extension spring system then it is usually possible to get it converted to a torsion spring system. Many garage doors are designed to work with both systems which makes converting one to the other much easier and far less expensive than it would otherwise be. It's a good idea to get a professional to do this conversion rather than doing it yourself as there is a lot of energy bound up in the springs in the door you can hurt yourself if you don't know what you are doing and aren’t following the proper safety tips.

Bottom Line 

It's worth learning how garage door works, as your door opening machinery will wear out over time and eventually break. Once this happens you will be left with the problem of getting the door open without the mechanism that makes the whole process manageable, and even possible in the case of heavier doors. The more tips and knowledge you know, the less risk you have of hurting yourself by tampering with something that may have parts under dangerous tension -- even if you’re simply replacing your garage door opener.