Background and Identification
A garage door opener is a motorized device that opens and closes garage doors and is controlled by switches on the garage wall. Most garage door openers include a handheld radio remote control that is carried by the owner and can be used to open and close the door from short distances away.
The electric overhead garage door opener was invented by C.G. Johnson in 1926, though electric garage door openers did not become popular until Era Meter Company began to sell them after World War II. These overhead garage doors could be opened using a keypad located on a post at the end of the user’s driveway or with a switch inside the garage.
Similar to an elevator, a garage door opener’s electric motor does not provide the majority of the power to move the door. Rather, most of the garage door’s weight is offset by the counterbalance springs attached to the garage door. Manually-operated garage doors also have counterbalances, allowing an individual person to be able to open or close the door. Typically, torsion springs are used to apply torque to a shaft, and that shaft applies a force to the door with steel counterbalance cables. The electric garage door opener is generally used to provide only a small amount of force, controlling how far the garage door opens or closes. The garage door opener can also hold the door closed in the place of a lock.