Springs and cables rarely fail because of the cold alone. They fail because they were already worn, and a cold morning adds the last bit of stress. Steel gets less forgiving in the cold, lubricant thickens and doors get stiffer, so a tired spring snaps on the first cycle of the day. If one breaks, stop using the door, keep people and vehicles out from under it, and call for repair.
The short answer
A torsion or extension spring is a piece of steel that is wound and unwound every time the door moves. Each cycle adds a little fatigue. After enough cycles, a small crack forms and grows until the spring breaks. The cold does not create that crack. It just tends to be the moment the crack finally gives way.
In Surrey, the first cold snaps of the season are often when a worn spring finally shows it. Inland areas such as Cloverdale and Clayton Heights see slightly colder nights than the rest of the city, and doors on shops and warehouses there often show it first.
What changes on a cold morning
Several small things stack up when the temperature drops overnight.
- Steel is less forgiving. A spring that is already cracked has less give in the cold, so the crack is more likely to run through on the first cycle.
- Lubricant thickens. Grease on bearings, hinges and rollers gets stiffer, so the door takes more effort to start moving.
- Seals stick. A bottom seal that is damp from the autumn rain can cling to the slab, adding load just as the door begins to lift.
- The operator pushes harder. A motor working against a stiff door puts extra strain on the springs, cables and drums.
- First cycle of the day. The door has sat still and cold all night, and then a crew opens it at the start of a shift.
None of these breaks a healthy spring. Together, they can finish one that was near the end of its life.
Why cables go too
Lift cables run from the bottom corners of the door up to the drums on the spring shaft. Damp air rusts the strands from the inside, and a door that is out of balance makes one cable carry more than its share. A frayed cable can snap without warning, and when one side lets go the door can twist in its track.
Busy doors wear out faster
A service bay in Newton or a loading door in an industrial unit near Guildford might open and close many times a day. Every cycle uses up part of a spring's life. Standard springs on a busy door can wear out much sooner than expected. High-cycle springs are built for that kind of use and last longer on busy bays.
Signs a spring or cable is about to go
You can spot many failures ahead of time if staff know what to look for.
- A visible gap between coils on a torsion spring
- Rust on springs or cables, or cables with loose or broken strands
- A door that feels heavy, lifts unevenly or drifts down when stopped partway
- The operator straining, slowing down or stopping before the door is fully open
- Squealing or grinding from the spring shaft or drums
What to do when a spring or cable breaks
A broken torsion spring usually makes a loud bang, like something heavy dropping. The door may then refuse to open, or open only a few inches before the operator gives up. A broken cable often leaves the door hanging crooked.
Make the area safe
- Stop using the door. Do not press the wall button again or try to force it open with the operator.
- Keep everyone out from under it. A door with a broken spring or cable can drop with no warning.
- Move forklifts, trucks and stock away from the opening if you can do so without going under the door.
- If the door is stuck partway open, leave it where it is. Do not try to pull it down or prop it up.
- If the opening needs to be secure overnight, tell the repair company so the door can be made safe on the first visit.
What not to do
Do not try to wind, adjust or replace a torsion spring yourself. The spring holds a large amount of stored energy, and the winding process needs the right tools and training. Loose cables and drums under spring tension are just as dangerous. This is work for a technician.
Getting the bay back in use
When you call, have the door size, a rough idea of its age, whether it is sectional or roll-up, the operator brand if it has one, and photos of the damage. Most spring, cable and roller repairs take a few hours. If you run deliveries through that door, the repair can often be booked early or late so the bay is out of use for as little time as possible.
If one spring has broken on a door with two, it usually makes sense to replace both, since the other has done the same number of cycles.
Getting ahead of the next cold snap
Fall is the time to have springs, cables and balance checked on every door at a site in Fleetwood, South Surrey or anywhere else across the city. A worn spring found in October is a planned repair. The same spring found on a frosty morning is a door that will not open when the first truck arrives.
When to call a professional
Call as soon as you hear a bang, see a frayed cable, or notice a door that has gone heavy or crooked. Those are not problems to work around for a few weeks. If nothing looks wrong but your doors have not been checked in a long time, booking an inspection before the coldest mornings is a reasonable step.