Garage Door Glossary: Common Terms Explained
Plain-language definitions for the terms you’ll see across this site and hear from any technician.
Springs & Lifting
Torsion Spring
A spring mounted horizontally on a metal shaft directly above the closed door. It winds and unwinds to lift the door and is the most common spring type on doors installed in the last 20 years. See our spring repair page.
Extension Spring
A spring that runs along the upper tracks on either side of the door and stretches to provide lifting force. More common on older or lighter doors. See our comparison guide.
Cable
A steel cable that works alongside the springs to guide the door evenly as it lifts. See our cable repair page.
Drum
The spool at each end of the torsion spring shaft that the cables wind around as the door opens and closes.
Openers & Electronics
Trolley
The part that connects the opener’s drive chain or belt to the door itself. When disconnected (often via the emergency release cord), the opener can run without moving the door.
Drive Gear
The internal gear inside the opener motor that translates the motor’s spin into movement along the chain or belt. A common failure point in older openers.
Photo-Eye Sensor
The small sensors mounted near the floor on each side of the door that detect obstructions and prevent the door from closing on a person, pet, or object.
Travel Limit
The opener setting that tells the door how far to travel before stopping, both fully open and fully closed. Drifting limits can cause a door to stop short or reverse unexpectedly.
Learn Button
The button on the opener motor unit used to pair or reprogram a remote or keypad.
Tracks & Hardware
Track
The metal rail the door’s rollers travel along as it opens and closes. See our track replacement page.
Roller
The wheel attached to each door panel that rolls along the track. Available in steel or nylon. See our roller replacement page.
Hinge
The metal bracket connecting door panels to each other and holding the rollers in place.
Weatherstripping
The rubber seal along the bottom and sides of the door that blocks drafts, moisture, and pests. See our weatherstripping page.
Door Structure
Panel
One section of a sectional garage door. Damaged panels can sometimes be replaced individually. See our panel replacement page.
Jamb
The vertical framing on either side of the garage door opening that the track hardware attaches to.
Header
The horizontal framing above the garage door opening.
Balance
How evenly a door’s weight is supported by its springs. A balanced door stays in place when lifted halfway and released; an unbalanced door strains the opener and wears out faster.
Still Not Sure What’s Wrong?
Try our free troubleshooting tool, or check our full FAQ page.