Um pouco de graxa nos cabos ou mancais das portas suspensas faria com que as molas quebrassem?

9

I have a roll-up (2 car-width) garage door. The right top torsion spring broke. I would have fixed it myself, but no time. I called out a repair company, and they guy came out and said that I need to replace both torsion springs. He claimed that the rollers were the cause of the springs snapping and that the rollers weren't moving. Said there was garage lube (lithium grease on the rollers) preventing them from moving.

Is this guy lying to me, or can this spring snapping be caused by rollers not moving? He also said there was lithium grease or lubricant on the garage door rails. Would grease cause these rollers to cease movement? Seems kinda sketchy to me, but want to rule this out.

insira a descrição da imagem aqui

por Dan Pollack 12.06.2019 / 16:48

3 respostas

TLDR: The spring failed naturally due to old age or manufacturing defect. Not your fault. As an aside, learn to properly grease garage doors.

Oh boy. The bull-oney here is thick. Let's start with Springs vs Door Motion.

The Spring is a counterweight. THAT IS ALL.

We're not even talking about lifters yet. Just the door, with no external forces to move it. Capische?

The door is heavy. You could not hand-lift it. You não deveria rely on an active mechanism to sheer-muscle-lift that door. Why not? First if the lifter breaks, the door guillotines and everyone under it is dead. Problems start out as minor (and reveal by stiff motion) so you want to detect that early, not brute force it, breaking the door further until guillotine. So muscle-lifting a door is Right Out.

The trick with counterweighting a door is as it rolls upward, it weighs less and less, because part of it is going horizontal. That is pretty linear. Springs are also "pretty linear", so they're a natural.

The point of counterweighting is that the door weighs effectively zero in all positions and will stay where you put it, not wanting to go up more than down in any position.

The counterweight interacts ONLY with the door. If the door moves, the counterweight imediatamente tracks with it. No interference! If the counterweight slackens, catastrophe follows. Which brings us to the First Rule Of Garage Doors:

Opening forces act ONLY on the door, never the counterweight.

We had four large 14x20' tall doors. The door and spring were conventional, but some genius put a geared lifter on the spring shaft. Worked going up. But going down, you were slackening the spring, and hoping gravity would pull the door down to keep the cable taut. Springs are instant. They follow the door motion no matter where it goes and how fast. Doors, not so much, especially when horizontal and gravity isn't working on them. The cable did not remain taut, came off the spool, guillotined... And that's why you never do that.


So. Back to your problem. Assuming your installer did not make the above mistake... It does not matter how the door moves. The spring counterweight should be able to keep up with it no matter what. Therefore, anything that affects door motion - like grease in the tracks - has no bearing on the performance of the spring.

The spring failed all by itself, in its own time, simply because it was old. Final answer.

Why are you greasing door tracks?

Grease is not a magical "make things move that should" elixir. Actually, making things not stick together is a complex problem that you can't just throw one chemical at. And garage doors are a case in point of this.

Grease, being sticky, is a magnet for dirt and dust. Those are abrasivo, so the net effect of greasing is the opposite - you might as well have used spray sandpaper. Grease makes sense inside areas sealed from the environment, like roller bearings.


Now what about door tracks? Remember how a door functions. The vertical part of the track, the track is basically a guide. The door is hung by the counterweight cables, and has basically no horizontal motion at all, except for wind loads. So on a still day, garage door rollers are doing zero work (in the vertical) and certainly don't need any grease.

But, the horizontal part of the door tracks? When the door is horizontal, all its weight rests on the rollers, and that's where they earn their pay. (However if your door is sticky when it's barely open, that's not the problem since it isn't horizontal). Effectively, the horizontal track is a estrada and the rollers are the rodas de bicicleta. Now let me ask you something. To make your bike roll freely, do you grease the road? Of course not! You make sure your bike wheels are top top. You limpar the road to keep debris out of it, because debris slows you down.

The same here with garage door rollers. Make sure the rollers are tip-tip. Don't lubricate them with grease, because dirt magnet. Rollers are cheap and if they seem to be anything but excellent, just replace them. As for the horizontal pista, make sure it is spic-and-span. Particularly remove any grease and the accumulated dust/dirt/sawdust that it attracted, that got up there.


There is one spot that really does need lubrication, but grease really will not do. You notice the garage door's track is on a very slight angle, so the door slides slightly para the building as it drops. At bottom, it makes a tight seal to the building.

If the door is sticky at the first few inches of opening, look there. However, grease is right out, because it'll get on your clothing. Go to a tractor supplier and get a quart of Paint-On Graphite Lubricant and a few acid brushes. This stuff looks, walks and quacks like dark grey paint, but is nicely slick. It's oil based, so be prepared to throw the brushes away.

The graphite is heavy, and adora mesmo to settle to the bottom leaving useless resin at the top. It's like cookie dough on the bottom and water on the top, and it takes 20 minutes to hand stir it to lump-free. So ask the hardware store to give it a good long run in their paint shaker upside down. (Buy quarts; the gallon is too heavy and would break their paint shaker).

To keep it from separating while you paint, pour out 1/4" of depth into a paint cup or old soup can, at that depth it will stir as you wet your brush.

Rollers are cheap and I don't sweat just replacing them, but graphite paint is one thing I will use on rollers with open bearings. A light touch will suffice, don't drown it.

12.06.2019 / 19:03

Torsion springs have a finite lifespan. They break. I seriously doubt that a little grease was a factor. Replace them ambos and move on with life.

After you've done so, disconnect the opener (if present) and lift the door to mid-height. Does it balance there? Does it move freely throughout the range of travel? If not, deal with that. If so, you're done.

Be aware that these springs must be replaced with identical models. Number of rotations and wire size is critical for proper operation. Too many turns and the door will have too much upforce when open or too much downforce when closed. Too few and your cable will jump the pulley when open.

12.06.2019 / 16:57

Steel springs fail by fatigue determined by stress and number of cycles unless the stress is below the endurance limit where they have unlimited life. There are a few cautions:

  1. The manufacturer may use a smaller ,cheaper spring ,
  2. there can be defects in the steel.
  3. Corrosion can pit the steel, increasing stress at that point.
  4. Service loads may be higher than expected, such a rollers that drag and skid because they are not lubricated.
  5. Stuff I forgot.

So, to maximize life - lubricate the rollers so that they roll. Coat the whole spring with a light coating of oil to reduce possible corrosion pits. And check the adjustments and factors of the other answers.

13.06.2019 / 18:03