# Garage door glossary The words that turn up on a quote and nobody explains. Every part carries its safety verdict. [Torsion springCall a professional](https://garagedude.shop/glossary/torsion-spring/)[Extension springCall a professional](https://garagedude.shop/glossary/extension-spring/)[Lift cableCall a professional](https://garagedude.shop/glossary/lift-cable/)[Cable drumCall a professional](https://garagedude.shop/glossary/cable-drum/)[Bottom bracketCall a professional](https://garagedude.shop/glossary/bottom-bracket/)[Winding barCall a professional](https://garagedude.shop/glossary/winding-bar/)[Counterbalance systemCall a professional](https://garagedude.shop/glossary/counterbalance/)[CycleOne opening plus one closing. Springs are rated in cycles rather than …](https://garagedude.shop/glossary/cycle/)[High-cycle springCall a professional](https://garagedude.shop/glossary/high-cycle-spring/)[Photo eyeSafe to DIY](https://garagedude.shop/glossary/photo-eye/)[Edge sensorDIY with caution](https://garagedude.shop/glossary/edge-sensor/)[Entrapment protectionThe systems that stop a closing door trapping a person. Federal rule 1…](https://garagedude.shop/glossary/entrapment-protection/)[Inherent primary entrapment protectionThe opener sensing an obstruction itself, by force or travel, and reve…](https://garagedude.shop/glossary/inherent-primary/)[Secondary entrapment protectionAn external device — photo eye, edge sensor or equivalent — that rever…](https://garagedude.shop/glossary/secondary-entrapment/)[Reversal testSafe to DIY](https://garagedude.shop/glossary/reversal-test/)[Emergency releaseSafe to DIY](https://garagedude.shop/glossary/emergency-release/)[UL 325The safety standard for door, gate and window operators. Its entrapmen…](https://garagedude.shop/glossary/ul-325/)[16 CFR 1211The federal Safety Standard for Automatic Residential Garage Door Oper…](https://garagedude.shop/glossary/cfr-1211/)[Unattended operationClosing the door without someone present to watch it, as from a phone …](https://garagedude.shop/glossary/unattended-operation/)[RollerDIY with caution](https://garagedude.shop/glossary/roller/)[HingeDIY with caution](https://garagedude.shop/glossary/hinge/)[TrackDIY with caution](https://garagedude.shop/glossary/track/)[StrutDIY with caution](https://garagedude.shop/glossary/strut/)[Jamb bracketDIY with caution](https://garagedude.shop/glossary/jamb-bracket/)[Center bearing plateCall a professional](https://garagedude.shop/glossary/center-bearing/)[End bearing plateCall a professional](https://garagedude.shop/glossary/end-bearing-plate/)[Weather sealSafe to DIY](https://garagedude.shop/glossary/weather-seal/)[AstragalSafe to DIY](https://garagedude.shop/glossary/astragal/)[Stop mouldingSafe to DIY](https://garagedude.shop/glossary/stop-moulding/)[Threshold sealSafe to DIY](https://garagedude.shop/glossary/threshold-seal/)[Garage door openerDIY with caution](https://garagedude.shop/glossary/opener/)[Chain driveAn opener that moves the trolley with a metal chain. Cheapest and loud…](https://garagedude.shop/glossary/chain-drive/)[Belt driveAn opener using a reinforced rubber belt instead of a chain. The usual…](https://garagedude.shop/glossary/belt-drive/)[Screw driveAn opener that moves the trolley along a threaded steel rod. Fewer mov…](https://garagedude.shop/glossary/screw-drive/)[Direct driveAn opener where the motor itself travels along a stationary chain in t…](https://garagedude.shop/glossary/direct-drive/)[Jackshaft openerA wall-mounted opener driving the torsion shaft from beside the door, …](https://garagedude.shop/glossary/jackshaft/)[TrolleyDIY with caution](https://garagedude.shop/glossary/trolley/)[Travel limitSafe to DIY](https://garagedude.shop/glossary/travel-limit/)[Force settingSafe to DIY](https://garagedude.shop/glossary/force-setting/)[Learn buttonSafe to DIY](https://garagedude.shop/glossary/learn-button/)[Rolling codeA security scheme where the transmitted code changes on every press, s…](https://garagedude.shop/glossary/rolling-code/)[Battery backupSafe to DIY](https://garagedude.shop/glossary/battery-backup/)[Sectional doorThe common US garage door: horizontal panels hinged together that trav…](https://garagedude.shop/glossary/sectional-door/)[One-piece (tilt-up) doorA single rigid slab that swings out and up as one panel. Common on old…](https://garagedude.shop/glossary/one-piece-door/)[Roll-up doorA door of narrow slats that coils around a drum above the opening. Mor…](https://garagedude.shop/glossary/roll-up-door/)[Carriage house styleA look imitating swing-out barn doors. Usually a standard sectional do…](https://garagedude.shop/glossary/carriage-house/)[Rough openingThe framed opening the door and its track fit into, measured before fi…](https://garagedude.shop/glossary/rough-opening/)[HeadroomThe distance from the top of the opening to the lowest ceiling obstruc…](https://garagedude.shop/glossary/headroom/)[BackroomThe depth needed behind the opening for the horizontal track and the o…](https://garagedude.shop/glossary/backroom/)[SideroomThe clear width needed at each side of the opening for the vertical tr…](https://garagedude.shop/glossary/sideroom/)[High-lift trackCall a professional](https://garagedude.shop/glossary/high-lift/)[GaugeSteel thickness on an inverse scale: a lower gauge number is thicker s…](https://garagedude.shop/glossary/gauge/)[R-valueThermal resistance, calculated through the centre of one door section …](https://garagedude.shop/glossary/r-value/)[U-factorThermal transmittance measured on the entire installed door assembly. …](https://garagedude.shop/glossary/u-factor/)[ANSI/DASMA 105The test standard for the U-factor of a complete garage door assembly,…](https://garagedude.shop/glossary/dasma-105/)[Thermal breakA non-conductive separation between the outer and inner skins of a doo…](https://garagedude.shop/glossary/thermal-break/)[Polyurethane insulationFoam injected into the door section, expanding to fill the cavity and …](https://garagedude.shop/glossary/polyurethane/)[Polystyrene insulationRigid foam board cut and fitted into the door section. Cheaper than in…](https://garagedude.shop/glossary/polystyrene/)[Wind loadThe pressure a door must resist without failing. In high-wind zones th…](https://garagedude.shop/glossary/wind-load/)[Notice of Acceptance (NOA)Miami-Dade County product approval, published per product. It covers t…](https://garagedude.shop/glossary/noa/)[High-Velocity Hurricane ZoneThe Florida designation covering Miami-Dade and Broward counties, wher…](https://garagedude.shop/glossary/hvhz/)[California SB 969The 2018 law requiring a battery backup on residential openers manufac…](https://garagedude.shop/glossary/sb-969/)[Design pressureThe positive and negative pressure a door is rated to withstand, set b…](https://garagedude.shop/glossary/design-pressure/)[BalanceCall a professional](https://garagedude.shop/glossary/balance/)[Off trackCall a professional](https://garagedude.shop/glossary/off-track/)[BindingDIY with caution](https://garagedude.shop/glossary/binding/)[Photo eye misalignmentSafe to DIY](https://garagedude.shop/glossary/photo-eye-misalignment/)[Stripped drive gearDIY with caution](https://garagedude.shop/glossary/stripped-gear/)[Safety cableCall a professional](https://garagedude.shop/glossary/safety-cable/)[Manual modeSafe to DIY](https://garagedude.shop/glossary/manual-mode/)[DASMAThe Door and Access Systems Manufacturers Association, which publishes…](https://garagedude.shop/glossary/dasma/)[CPSCThe US Consumer Product Safety Commission, the federal agency whose ru…](https://garagedude.shop/glossary/cpsc/) ## How does a garage door actually hold its own weight? A garage door is not lifted by the opener. It is lifted by the spring, and the opener only guides it. That distinction explains almost everything else on this page. A residential door weighs between 85 and 400 pounds depending on size and material. The counterbalance system — springs, cables, drums and bottom brackets — stores the energy needed to raise that weight and gives it back on the way up. With the counterbalance set correctly the door stays put when released halfway, and the opener only has to overcome friction. This is why an unbalanced door destroys openers: the motor ends up lifting a load it was never sized for. And it is why springs and cables are professional work while sensors and remotes are not — one group holds that stored energy and the other does not. The test is available to anyone. Disconnect the opener with the red release, lift the door halfway by hand, and let go. If it stays where you left it, the counterbalance is right. If it drifts down or shoots up, it is not, and CPSC says a door in that state should be serviced by a professional. ## How do I know whether a spring is what failed? Look at the spring itself before anything else. A fractured torsion spring shows a visible gap of roughly one to two inches in the coil, and it is the single clearest diagnostic on the whole door. Extension springs run along the horizontal tracks on each side and show the same break. The sound is the other tell. A spring failing releases its stored energy at once, and people consistently describe it as a bang loud enough to be mistaken for something falling over in the garage — often heard from inside the house. Then test the weight, carefully, with the opener disconnected and the door already closed. A door with an intact counterbalance can be lifted by one person. A door with a broken spring feels like what it is: 85 to 400 pounds of dead weight. If it will not move easily, stop and leave it closed. Do not use the opener to test this. With the spring gone the opener is lifting the entire door weight through a drive gear rated for a balanced load, which is how a spring bill becomes a spring and opener bill. ## What does federal law actually require here? More than most people assume, and in writing. Every residential opener manufactured on or after January 1, 1993 for US sale must meet 16 CFR 1211, which incorporates the entrapment protection provisions of UL 325. Three concrete requirements matter to a homeowner. A downward-moving door must begin reversing within 2 seconds of hitting an obstruction and return to the fully open position. There must be a second, independent protection system — a photo eye, an edge sensor, or an equivalent device — which must also prevent the opener closing an open door. And the manual release handle must be red , reachable at 6 feet, and release under no more than 50 pounds of pull. The part almost nobody cites is §1211.16(b), which specifies the exact words the manufacturer must print in your manual. Among them: “Have a qualified service person make repairs to cables, spring assemblies and other hardware.” That is why this page's verdict on springs and cables is not our opinion. [What UL 325 and 16 CFR 1211 require](https://garagedude.shop/safety/ul-325/) covers the full standard. ## What is the one-minute test everyone should be doing? The reversal test, monthly. This is not our advice — it is the text federal law requires the manufacturer to print in your opener's manual. > “Test door opener monthly. The garage door MUST reverse on contact with a 1½ inch object (or a 2 by 4 board laid flat) on the floor.” Lay it flat on the floor in the door's path and close the door. It must reverse on contact. If it does not, stop using the opener until it is adjusted per the manual, repaired, or replaced. It matters because this system fails silently. A door whose reversal has stopped working looks and sounds exactly like one that still does, right up until something is underneath it. CPSC reports about 73 children aged 2 to 14 trapped and killed under automatic garage doors since March 1982 — roughly 3 a year — and that record is why the standard exists. CPSC also recommends inspecting the door and opener every 30 days. [Children, pets and the garage door](https://garagedude.shop/safety/child-safety/) covers the rest. ## How long does this actually last, and why is it measured in cycles? Springs are rated in cycles, not years , and one cycle is one opening plus one closing. That is the difference between a specification and a rule of thumb, and it explains why two identical doors last different lengths of time. A standard spring is typically rated at about 10,000 cycles. High-cycle springs, wound from thicker wire on a larger inside diameter, run 25,000 to 100,000. Translate that to your own house. At 4 cycles a day — leaving for work, back at lunch, one errand — that is 1,460 cycles a year, so 10,000 cycles is a little under 6.8 years . A household with teenagers and two cars burns through them well before the "seven to ten years" figure that gets repeated everywhere. The cycle rating is a manufacturer specification rather than a standard, so you have to ask for it. It is also the number that makes two quotes comparable: without it, a cheap spring and a good one look identical on paper. ## At what point should I stop and call someone? There are four signals, and any one of them on its own is enough to stop. - The door is very heavy by hand with the opener disconnected. The counterbalance has failed, and nothing but you is holding the door. - You can see a gap in the spring coil , or a cable that is frayed, slack, or off its drum. - The door sits crooked , higher on one side, or has come off its track. It is still under full tension and can move suddenly. - The door does not reverse on the board test. The entrapment protection is not working. None of those is calling too early. They are precisely the cases where the federally required manual text directs the work to a qualified service person, and where the cost of being wrong is not a broken part. The rule worth teaching at home comes from that same federal text, in capitals: “NEVER GO UNDER A STOPPED PARTIALLY OPEN DOOR.” ## Questions that come up next ### Does a door that reverses mean something is broken? No — the opposite. A door that stops and goes back up when it touches something is the entrapment protection doing exactly what 16 CFR 1211 requires. The fault worth investigating is a door that fails to reverse. ### Can I disable the photo eyes to get the door closed? No. That removes the external entrapment protection required since 1993, and it is the protection that exists because of the CPSC child fatality record. If a sensor is genuinely faulty, replace it — it is among the cheapest parts on the door. ### Is it safe to use the emergency release with the door open? The federally required manual text says to use it only when the door is closed wherever possible, because weak or broken springs may allow the door to fall rapidly. A great deal of DIY content advises the opposite. ### Should I replace one spring or both? If the door has two, quote both. The second is the same age and has taken the same number of cycles, so it is next. This is one of the few upsells in the trade that is genuinely honest. ## Sources - [16 CFR Part 1211 — Safety Standard for Automatic Residential Garage Door Operators](https://www.ecfr.gov/current/title-16/chapter-II/subchapter-B/part-1211) — US Consumer Product Safety Commission Tier 1 accessed 2026-08-17 - [16 CFR 1211.16 — required installation and user instructions (81 FR 20231)](https://www.govinfo.gov/content/pkg/FR-2016-04-07/html/2016-07552.htm) — US CPSC via Federal Register Tier 1 accessed 2026-08-17 - [Publication 523 — Non-Reversing Automatic Garage Door Openers Are a Hazard](https://www.cpsc.gov/s3fs-public/garage.pdf) — US Consumer Product Safety Commission Tier 1 accessed 2026-08-17 - [Technical Data Sheet 163 — U-factor and R-value for Residential and Commercial Garage Doors](https://www.dasma.com/wp-content/uploads/2022/09/TDS163..pdf) — DASMA Tier 2 accessed 2026-08-17