Garage Door Repair Hugo MN › Parts Glossary
Garage Door Parts Glossary
Plain-language definitions of the parts of a sectional garage door and opener, with a note on which ones only a trained technician should touch. Definitions are paraphrased from DASMA terminology where noted.
Parts defined door, springs, tracks, opener
Pro-only flags springs, cables, bottom brackets
Source DASMA terminology
Diagrams track and spring
The door and its hardware
| Term | What it means |
|---|---|
| Section or panel | One horizontal piece of a sectional door |
| Hinge | Joins sections so the door bends through the curve |
| Roller | Wheel that guides the door along the track |
| Strut | A stiffener that reduces flex and helps with wind load |
| Weather seal | Material around the door that blocks air, including the bottom seal |
| Header | The frame piece above the opening |
| Jamb | The upright framing on each side of the opening |
Springs and cables: leave to a technician
DASMA calls springs the most dangerous part of the door and says cables and bottom brackets are for trained technicians only.
| Term | What it means | Who |
|---|---|---|
| Torsion spring | A spring on a shaft above the door that stores force by twisting | Technician |
| Extension spring | A spring that stretches along the horizontal track | Technician |
| Torsion shaft | The shaft that carries spring force to the drums | Technician |
| Drum | A grooved wheel on the shaft where the lift cable winds | Technician |
| Lift cable | Braided steel cable that lifts the door | Technician |
| Bottom bracket | The fitting on the bottom section that holds the roller and cable end | Technician |
| Spring anchor bracket | Fixes the spring assembly to the header | Technician |
| Center bearing plate | Holds a bearing that supports the shaft | Technician |
| Cycle | One full open and close of the door | n/a |
See spring repair and cable repair.
Tracks and brackets
| Term | What it means |
|---|---|
| Track | The metal channel the rollers ride in |
| Vertical track | The straight part beside the opening |
| Horizontal track | The part that runs along the ceiling |
| Radius | The curved section between the two |
| Jamb bracket | An L-shaped bracket that links the vertical track to the jamb |
| Flag angle | An L-shaped angle that connects the vertical track to the jamb, useful in low headroom |
See track repair and off-track repair.
The opener
| Term | What it means |
|---|---|
| Opener | The motor unit that raises and lowers the door |
| Chain, belt and screw drive | The three common drive styles, using a chain, a rubber belt or a threaded rod |
| Jackshaft opener | A wall-mounted opener that turns the door shaft |
| Safety sensors | Photo eyes near the floor that reverse the door if the beam is blocked |
| Auto-reverse | The door reverses when it meets an obstruction |
| Release cord | The red cord that disconnects the opener so the door can be moved by hand |
Definitions here are common trade usage. See the openers guide and the safety guide.
Room and ratings
| Term | What it means |
|---|---|
| Headroom | The clear space above the opening the door needs |
| Side room | The space beside the opening to the nearest obstruction |
| Backroom | The depth from the door into the garage to the first obstruction |
| R-value | Thermal resistance of the door section |
| U-factor | Heat loss through the whole installed door |
| Wind load rating | The wind pressure the door is designed to resist |
DASMA says U-factor and R-value are not reciprocals. See winter care.
Easy mix-ups
Torsion springs sit on a shaft above the door and twist. Extension springs stretch along the side tracks. The track belongs to the door, the rail belongs to the opener. The opener does not lift the door’s weight, the springs do.
Call about a garage door part
Describe what the door is doing, when it started and what you have already tried.
What to have ready
- Your address and the nearest cross street
- What the door is doing, and any bangs or smells
- Door material and approximate age, if you know
- Photos of the broken part, if you can