Door stuck?A loud bang and a door that won't lift is usually a broken spring.What to do

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Garage door parts

Parts of a garage door

Short answer: A sectional garage door hangs on springs, not on the opener. Torsion springs on a bar above the door, or extension springs along the tracks, carry its weight through cables and drums. Rollers ride in the tracks. The opener only pushes and pulls, and since 1993 it must reverse when it hits something, usually using two sensors near the floor.

Source: HomeBlue, garage door spring replacement cost · 16 CFR Part 1211, safety standard for garage door openers. Checked November 4, 2026.

What each part does, and which ones are safe to look at yourself.

The drawing

Not to scale. The torsion springs carry most of the door's weight through the cables and drums. When a spring breaks, the door feels like it weighs hundreds of pounds and the opener can't lift it. Some doors use extension springs along the tracks instead. Since 1993, openers must reverse when they hit something, and most use the two sensors near the floor as the second safety device.

What each part does

Torsion springs: coils on a steel bar above the door. They twist as the door closes and lift it as it opens. Some doors use extension springs along the tracks instead.
Cable drums and lift cables: the drums at each end of the bar wind the cables that run down to the bottom corners of the door.
Bottom brackets: where the cables attach. They are under tension too.
Tracks and rollers: the rollers ride in vertical tracks that curve back along the ceiling.
Panels: the sections of the door, joined by hinges.
Opener, rail and arm: the motor on the ceiling moves a trolley along a rail; an arm connects it to the top panel.
Emergency release: the red handle that disconnects the door from the opener.
Safety sensors: two photo eyes near the floor. When the beam is blocked, the door won't close.

Which parts to leave alone

Springs, cables, drums and bottom brackets hold the door's weight under high tension. Leave adjustments and replacements to a garage door company. You can safely clean and line up the sensors, replace remote batteries, and check the outlet.

Sources: HomeBlue, garage door spring replacement cost · 16 CFR Part 1211, safety standard for garage door openers · DASMA, factors affecting spring cycle life (PDF)