The most important part of the garage door opener is the springs. These springs are very powerful and under very high tension. This is why one can lift the garage door by him/herself. If one looks at the garage door, there will be a spring, or set of springs running across above the door itself. If the spring is mounted on either side of the door, it is called the extension springs. This is usually common among single car garages, because these are not strong enough to hold the double doors weight. Double doors on the other hand, use what is called the tension spring. This spring will be above the door. This type of spring winds up into a coil, which means when the door is closed, it holds a very large amount of tension in the spring. This means if it is set loose, it can be very dangerous. There are also other parts of the garage door. There are bottom brackets, cable drums, and the vertical and horizontal tracks.
There are generally three types of automatic garage door openers: Chain Drives, which are the most common, Belt Drives, which are the most quiet, and Screw Drives, which are the slowest. The most common example of a chain drive would be the bicycle. As the gear is turned, the chain moves which also moves the garage door. A belt drive is the same concept, except the chain is substituted with a belt. The screw drive system uses a long screw which is inside a rail. When the screw twists, the door moves along the track which lifts it.
Back then remote controls were not the smart choice. The transmitter would transmit on a certain frequency, and the receiver in the garage door opener would recognize that same frequency, then open the door. This is when multiple garages had the same frequency and the problem arose of people opening other people’s garages. Now, with updated technology, most transmitter use the hopping or rolling code technology. The transmitter has a memory chip that holds a 40-bit code. When you push the button on your remote, it sends the 40-bit code to the receiver. The receiver also has a chip that holds a 40-bit code. If the receiver gets the code it expects, it opens the garage door. On both of the transmitter and receiver, there are the same random generators. After each time the transmitter sends the code, it makes a new code, the same with the receiver.