Garage Door Repair Glossary

This garage door repair glossary is your quick-reference tool for the 12 most important terms every Somerville homeowner needs to know before winter arrives. Learn what each part does, why it matters, and when to call Jerry & Terry Garage Door's Repairs LLC before the first Nor’easter hits.

Garage doors in Somerville face brutal seasonal swings—from summer humidity to winter freeze-thaw cycles—so knowing the lingo helps you spot trouble early and keep repair costs down. Whether you’re troubleshooting a noisy roller or upgrading insulation before January’s sub-zero nights, this plain-English glossary explains the key parts and functions. Need a pro? See our full services or request a free estimate before peak season hits.

Torsion spring

A tightly wound metal spring mounted above the garage door that counterbalances the door’s weight, making it easy to open and close. Unlike extension springs, torsion springs unwind slowly to lift the door, reducing stress on the opener. If a torsion spring snaps in Somerville’s winter cold, the door can slam shut—call Jerry & Terry immediately to avoid damage or injury.

Extension spring

A spring that stretches along the sides of the garage door track, pulling the door upward when it opens. These springs are cheaper than torsion springs but wear out faster under heavy use or cold snaps. If you hear a loud bang near the door tracks in your Arlington home, it’s likely an extension spring breaking—schedule a spring replacement before it leaves your door unbalanced.

Track

The metal channels (usually vertical and horizontal) that guide the garage door as it moves up and down. Tracks must stay aligned and free of debris; even a slight bend can cause the door to derail or bind. In Somerville’s older homes, tracks often collect rust—inspect them during your fall tune-up.

Roller

The small wheels attached to the door’s sides that roll inside the track, keeping the door aligned and reducing friction. Nylon rollers last longer than steel in humid summers, while steel rollers can corrode. If your Medford garage door squeaks, worn rollers are often the culprit—replace them before winter’s damp air worsens the problem.

Opener

The motorized unit that automates your garage door’s movement, controlled by a remote, wall switch, or smart device. Modern openers (like Chamberlain or LiftMaster) include safety features like auto-reverse and photo-eye sensors. If your opener struggles in Everett’s cold, check the power source or call Jerry & Terry for a diagnostic.

Photo-eye sensor

A pair of infrared beams mounted near the garage floor that detect obstructions (like a child’s bike or pet) and stop the door from closing. If the sensor is dirty or misaligned, the door may reverse unexpectedly. Test yours monthly—especially before winter sets in—to avoid a costly repair; Somerville’s foggy mornings can obscure the beams.

Limit switch

The safety device that tells the garage door opener when to stop moving up or down. If the limit switch is set too high or low, the door won’t fully open or close, straining the opener. In older Cambridge homes, limit switches often drift with age—adjust them during your winter prep.

Weatherstripping

The rubber or vinyl seal along the bottom and sides of the garage door that blocks drafts, pests, and moisture. High-quality weatherstripping with a high R-value (see below) keeps your garage (and home) warmer in winter. Check it annually—especially in Somerville’s windy neighborhoods like Union Square—before the first freeze.

R-value (insulation)

A measure of how well garage door insulation resists heat flow; higher R-values (e.g., R-12 or R-16) mean better temperature control. Insulated doors reduce energy bills and prevent ice buildup on the door in Watertown’s cold winters. If your door feels like a sheet of metal in January, consider upgrading during your insulation service.

Cable drum

The cylindrical spool that winds and unwinds the lift cable as the garage door opens or closes. If the cable drum is cracked or the cable slips, the door can become unbalanced or even fall. In older Belmont homes, cable drums often wear out—replace them during a spring replacement to avoid a dangerous failure.

Bottom seal

The thick rubber strip attached to the bottom edge of the garage door that seals the gap between the door and the driveway. A worn bottom seal lets in water, pests, and cold air—especially problematic in Somerville’s low-lying areas like Teele Square. Replace it every 2–3 years or after a harsh winter.

Travel module

The electronic brain of modern garage door openers that controls speed, force, and safety features. If your opener acts erratically (e.g., stops mid-cycle), the travel module may need reprogramming or replacement. In Lexington’s newer subdivisions, travel modules often fail after power surges—schedule a diagnostic if your door behaves strangely.

Trolley

The part of the garage door opener that moves along the rail, pulling the door open or closed via the arm. If the trolley is misaligned or the arm is bent, the door won’t operate smoothly. In Arlington’s hilly neighborhoods, trolley issues are common—check it during your seasonal maintenance.

Manual release

A red-handled cord or lever inside the garage that disconnects the door from the opener, allowing you to open or close it by hand in a power outage. Always test yours twice a year—especially before a Nor’easter—to ensure it works. If the cord snaps or the release is stuck, call Jerry & Terry to avoid being locked out during a winter blackout.

Frequently Asked Questions