Glossary

Garage door parts names and terms

Connecticut Garage Door Repair put together this list of garage door parts names so you can describe the problem on the phone and understand a quote. Parts marked as under tension are for technicians only.

Springs and counterbalance

Torsion spring: A tightly wound spring mounted on a steel shaft above the door. It twists as the door closes and unwinds to lift it. HomeAdvisor rates torsion springs at 10,000 to 20,000 cycles. See torsion vs. extension springs.
Extension spring: A long spring that stretches along each horizontal track when the door closes. Always used in pairs; rated at 8,000 to 15,000 cycles per HomeAdvisor. Each needs a safety cable.
Safety cable: A cable threaded through the center of an extension spring and anchored at both ends, so a broken spring stays contained instead of flying across the garage.
Cycle rating: How many open-and-close cycles a spring is designed for. One cycle is one open plus one close. High-cycle springs are rated for 20,000 or more.
Counterbalance: The spring system's job: offsetting the door's weight so it lifts easily and stays put when stopped halfway. A balanced door is the test of a correct spring repair.
Winding cone: The cast fitting at the end of a torsion spring that technicians turn with winding bars to set its tension. Not a homeowner part.

Cables, drums, and brackets

Lift cable: The steel cable on each side of the door, running from the bottom bracket to the cable drum (torsion) or pulleys (extension). Usually frays first near the floor. See off-track and cable repair.
Cable drum: The grooved spool at each end of the torsion shaft that the lift cable winds onto. A cable that jumps its drum is a common reason doors hang crooked.
Bottom bracket: The bracket at each lower corner of the door where the lift cable attaches. It's under spring tension; never loosen it.
Torsion shaft (tube): The steel bar above the door that carries the torsion springs and cable drums.

Door, tracks, and rollers

Section (panel): One of the horizontal pieces, usually four or five, hinged together to make a sectional door. A damaged section can often be replaced alone. See panel repair.
Vertical and horizontal track: The steel channels the rollers ride in: vertical beside the opening, horizontal along the ceiling, joined by a curved radius.
Roller: The wheels on stems that ride in the track. Worn rollers make noise and can throw the door off track.
Strut (reinforcing bar): A horizontal steel stiffener on the inside of a section, common on wide doors and on the top section where the opener attaches.
Bottom seal (astragal): The rubber or vinyl strip along the bottom of the door. It freezes to the slab in Connecticut winters and tears when the door is forced.
Weatherstripping: Seals along the sides and top of the door opening that keep out drafts, water, and pests.
R-value: A measure of an insulated door's resistance to heat flow. Higher is better; insulation adds weight, so springs must be sized to the door.

Openers and safety

Photo eyes (safety sensors): A pair of sensors mounted 4 to 6 inches above the floor that reverse a closing door when something breaks the beam. Required on openers made since January 1, 1993 under 16 CFR Part 1211.
Auto-reverse: The opener's built-in response to resistance or a blocked sensor: it stops and reverses the door. It's tested at the end of any proper repair.
Emergency release: The red cord that disconnects the door from the opener so it can be moved by hand. Use it only with the door fully closed; with a broken spring, an open door can drop.
Trolley: The carriage that rides along the opener's rail and connects to the door's top section; the emergency release detaches it.
Chain, belt, screw, and wall-mount drives: How the opener moves the trolley. Chain drives are least expensive, belt drives quietest, screw drives have few moving parts, and wall-mount (jackshaft) openers turn the torsion shaft directly. See opener repair.
Travel limits and force settings: Opener settings that control how far the door moves and how much resistance triggers a reverse. Adjusting them is part of the safety system and best left to a technician.
Logic board: The opener's circuit board. A failed board is one of the more expensive opener repairs and often a reason to replace an older opener.

Connecticut rules

HIC registration: Connecticut's home improvement contractor registration with the Department of Consumer Protection. Required for residential work over $200, including garage doors. It requires liability insurance and a fee, not an exam. See how to check a company.
eLicense: Connecticut's free online lookup for licenses and registrations, at elicense.ct.gov.
Three-day cancellation right: Connecticut home improvement contracts let you cancel until midnight of the third business day after signing; Saturday counts. A bona fide emergency you request in writing is the only exception.
Home Improvement Guaranty Fund: A state fund that can reimburse eligible homeowners up to $25,000 when a project with an actively registered contractor goes wrong.
Wind-load rating (ANSI/DASMA 108): The test standard Connecticut's building code (based on the 2021 International Residential Code) uses for garage door wind-load performance.

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