What component of the garage door opener connects to the door arm?

The component of the garage door opener that connects to the door arm is the trolley. The trolley serves as a key mechanism that moves along the rail when the garage door opener is activated. Attached to the door arm, it transfers the motion generated by the opener to the garage door itself, allowing the door to ascend and descend smoothly.

In addition to its connection to the door arm, the trolley is designed to engage and disengage, which provides the ability to operate the door manually when necessary. This feature is important in situations where power might be lost, allowing users to open or close the garage door without relying on the electric opener.

Other components like the rail, motor unit, and drive mechanism, while essential to the overall functionality of the garage door opener, do not perform the direct connection to the door arm. The rail serves as the pathway for the trolley, the motor unit drives the trolley along the rail, and the drive mechanism refers to the way power is transmitted in the opener, but the specific connection made to the door arm is accomplished solely by the trolley.