Reference
Garage door glossary
17 garage door parts and terms in plain language. Springs and cables are high-tension parts — they're for trained technicians, not DIY.
Lifting & counterbalance
- Torsion spring
- A tightly wound spring mounted on a bar above the door that stores energy to counterbalance the door's weight so the opener (or a person) can lift it. It is under high tension and is not a DIY part.
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- Extension spring
- Springs mounted along the horizontal tracks that stretch and contract to counterbalance the door, most common on lighter single-car doors. Like torsion springs, they are high-tension components.
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- Lifting cable
- The steel cable that connects the bottom bracket to the spring system and carries the door's weight as it travels. Fraying or a snapped cable makes the door hang unevenly and unsafe to operate.
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- Cable drum
- The grooved wheel at each end of the torsion bar that winds and unwinds the lifting cable evenly, keeping both sides of the door balanced during travel.
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- Door balance
- How well the spring system offsets the door's weight. A balanced door holds its position when raised halfway; a door that slams down or springs up is out of balance and strains the opener.
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Movement & guidance
- Track
- The metal channel on each side (and overhead) that guides the door's rollers through its path. Bent or misaligned track causes binding, grinding, and off-track doors.
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- Roller
- The small wheels attached to each door section that ride inside the track. Worn or seized rollers cause noise, drag, and uneven movement.
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- Hinge
- The hardware that connects door sections so they flex around the track's curve. Loose or cracked hinges create noise and let sections shift out of alignment.
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- Off-track door
- A door whose rollers have left the track, usually after a broken cable, an impact, or a seized roller. An off-track door is unstable and should not be operated until inspected.
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Opener & safety
- Opener (operator)
- The powered unit that drives the door open and closed via a chain, belt, or screw. The opener guides movement — the springs do the heavy lifting — so a humming opener that won't lift often points to a spring or balance problem, not the motor.
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- Photo-eye sensor
- The pair of sensors near the floor on each side of the opening that stop and reverse a closing door if the beam between them is blocked. Misaligned or dirty photo eyes are a common reason a door reverses on its own.
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- Auto-reverse
- The safety function that reverses a closing door when it meets resistance or the photo-eye beam is broken. It should be tested periodically to confirm the door does not continue closing on an obstruction.
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- Limit switch
- The opener setting that tells the door how far to travel to fully open and fully close. Incorrect limits leave a gap at the floor or make the door reverse before it seals.
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- Manual release
- The emergency cord that disconnects the door from the opener so it can be moved by hand during a power failure. Pulling it on a door with a broken spring is dangerous because the door is then unbalanced.
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Sealing & upgrades
- Weatherseal (bottom seal)
- The flexible strip along the door's bottom edge (and perimeter) that blocks drafts, water, and pests. Cracked or flattened seals are a common, low-cost maintenance replacement.
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- Insulated door
- A door built with a foam core between steel skins to reduce heat transfer and noise — useful for attached garages and rooms above the garage.
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- R-value
- A measure of a door's resistance to heat flow; a higher R-value indicates more insulation. It is one factor among construction and sealing when comparing replacement doors.
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Want the bigger picture? Browse the Learning Center.
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