If you’re a curious soul or a DIYer, it’s good to know how your garage door opener works. It’ll help when shopping for a new one, fixing an old one, or explaining what’s wrong while speaking over the phone to a professional repair person.

Three elements work together to form a garage door opener: a spring system, tracks, and drive mechanism. The spring system lifts and lowers the garage door. The tracks guide the garage door. And the drive mechanism – which includes a motor and chain system – moves the garage door.

Attached to the drive mechanism is a sensor. Your remote control sends a signal to this sensor, telling it to open or close the garage door. The sensor then directs the drive mechanism to move the door along the tracks until the desired function is completed.

There are three types of garage door opener systems: chain drive, belt drive and screw drive. Each works basically the same way.

Chain drive. This is the oldest method and the cheapest. It’s also the loudest. A chain – not unlike a bicycle chain – moves the door as the tracks guide it.

Belt drive. It’s usually the quietest (and most expensive) style of garage door openers. A belt of Kevlar polymer is molded so that one side is serrated. These teeth rotate through a gear to pull the door.

Battery backup. You usually only find this feature in higher-end models, but it’s a good one to have. It enables you to keep using your garage door opener during power outages.

Screw drive. This system employs a long, threaded steel rod which turns, pushing or pulling the door into position. The downside? It wears out the trolley quicker than the other two options. However, it’s usually less expensive than a belt drive, and less noisy than a chain system.