A broken spring removes part or all of the counterbalance that makes a garage door manageable. The door may still move, but that does not mean moving it is safe for the opener or the people nearby.
Why the door suddenly feels much heavier
Garage-door springs counterbalance the weight of the sections. When a torsion or extension spring breaks, the opener may be asked to lift weight it was not designed to carry alone. The motor can strain, the trolley or drive components can fail, and the door can move unevenly if the cable system is no longer balanced.
Common signs include a loud bang, a visible gap in the torsion coil, a door that rises only a few inches, or one side moving before the other. Stop using the opener when those signs appear.
Do not assume a closed door is harmless
A closed door is usually the most stable position, but spring and cable hardware can still be under tension. Do not loosen winding cones, drums, bottom brackets or extension-spring attachments. Those are not ordinary fasteners.
If extension springs are installed beside the tracks, they should have containment safety cables. DASMA notes that an extension spring remains highly tensioned when the door is down and that a safety cable helps contain a spring if it breaks.
What if a vehicle is trapped inside?
Do not improvise with the opener, tow straps or people lifting from uneven positions. Tell the repair provider that a vehicle is trapped, whether another exit exists, and whether the door is level and fully closed. That information changes how the call is prepared.
If there is an immediate life-safety emergency, use emergency services. Property convenience alone is not a reason to work beneath or force an unsupported door.
What to send before service
Photograph the complete door from inside the garage, the spring assembly above or beside it, both cable drums or lower corners, and the opener rail. State whether the door is open, closed or between positions. Those details help distinguish a broken spring from a cable, track or opener fault.
Safety reference
This guide also reflects consumer-safety guidance published by DASMA: garage-door system safety tips.