5 ms·

I don’t understand why it’s even considered safe to have one of these springs in one’s garage without a solid shield of some sort. While the energy involved is

• imoverclocked 3y ago
  > A rather small motor with a lot of mechanical advantage can easily open a close a garage door, and if a DC or low voltage AC motor is used, it could do so quite a few times even if the power goes out. Garage doors are actually fairly heavy. By balancing the weight with a spring, you do a lot of favors to your mechanical advantage systems. (Eg: less wear, less advantage needed, the door can open in a reasonable amount of time…) You also do yourself a few favors for when things fail. (Eg: you pull the safety release and it’s possible to open the door without the motor.) Finally, power isn’t free and motors aren’t either; A spring is a really cheap way to reduce the cost of both of these things.
  • BizarroLand 3y ago
    I imagine that garage door openers would either need to be a lot beefier or would work a lot slower without the springs.
  • codethatwerks 3y ago
    What about a counterweight or a piston instead (pistons are used in pull down beds which might be a similar load)
    • nradov 3y ago
      Sure, but then you have to put the counterweight somewhere which would occupy garage floor or wall space. And the counterweight track would have to be enclosed for safety.
      • shiroiushi 3y ago
        It's easy: you dig a deep shaft under the garage and put the counterweight in there. Of course, there may be some cost issues with this solution...
        • naikrovek 3y ago
          you have an odd definition for "easy" I think. garage door springs are safe if you are careful and you use the correct tools and procedures. the instant you take a shortcut with these, you increase the likelihood of a bad outcome. so, don't take shortcuts, and don't do the work if you don't know what you're doing. the professionals know this and that's why we pay them, but they're not special creatures with special abilities; they're people who understand that this is a situation which can bite you, and they act accordingly. Just about anyone can change their garage door springs, if they do so correctly.
        • kayodelycaon 3y ago
          Deep shafts have a tendency to flood. And that’s assuming you can drill one in the first place.
    • MadnessASAP 3y ago
      Still need to store the same amount of energy. A counter weight or piston also has more opportunities for uncontained failure. At least when a garage door spring fails it is still constrained by the shaft running through the middle. For what it's worth, I have also replaced my own garage door spring, and I really have no desire to do that again.
• kelnos 3y ago
  If the garage door opener breaks, or the power is out, many people might have a really tough time opening the door manually without those springs. They might not be able to even do it at all. It is still, of course, a valid question to ask if it's worth having dangerous springs up there all the time for the rare event of the opener being inoperative. Or maybe we just shouldn't have doors that are that heavy?
  • LoganDark 3y ago
    > many people might have a really tough time opening the door manually without those springs I think that would be most people. Who can lift over 450lbs from the ground?
    • codethatwerks 3y ago
      450lbs but because it is not straight up but up and back that probably gives a 2-1 leverage so 225lb or 100kg. using your legs to lift it would be in the realm of a regular male weight trainer but not the average jo or jane.
      • notact 3y ago
        Sure it gets progressively easier as more and more of the door rides horizontally on its rails. But those first few inches where the door is nearly entirely vertical, must be some significant fraction of the total weight, probably >90%.
        • LoganDark 3y ago
          Not to mention you have to get your fingers or something underneath the closed door in order to begin lifting it in the first place. So the "from the ground" part is not insignificant.
          • ComputerGuru 3y ago
            All garage doors I’ve seen had a heavy yank handle on the inside.
• itsgrimetime 3y ago
  I’m not an expert in how springs break but wouldn’t an ejection of material require the spring breaking in at least 2 places that are close enough to not loop around the rod? I’m curious if anyone’s ever been hurt by one breaking (other than when actively working on it).
  • spdustin 3y ago
    I’ve also never heard of a shrapnel-based injury. Only door falls or torsion bars breaking arms. I’ve actually replaced these in two houses, and yes, they’re dangerous, but honestly a little common sense and a straightforward (printed, with a buddy double-checking) list of steps you take with each quarter turn. It’s super important to have the right torsion bars. Don’t try to invent your own.
    • ethbr1 3y ago
      I am a terrible person and have done this twice with a couple angle-ground pieces of rebar (almost perfect diameter) + a pair of vice grips. On the one hand, nothing went wrong because I was careful. And rebar actually works really well. On the other hand, it was pretty dicey, especially near the maximally-wound state when you're putting serious muscle into another quarter turn. 110% agreed on it being a 2 person job though. Reason #1: so someone is there to call 911. Reason #2: you'll need someone to cable up the drums while you're adjusting the spring, and it's way easier with 2 pairs of hands.
    • outop 3y ago
      Realistically, any household maintenance task which needs a checklist and a second pair of eyes and arms to be done safely, is often going to be carried out by someone who feels that they can manage without either.
  • gh02t 3y ago
    I'm far from an expert but many (most?) kinds of spring are hardened steel. It's not hard to imagine how they might shatter under the right stress.
  • smitelli 3y ago
• sokoloff 3y ago
  > I don’t understand why it’s even considered safe to have one of these springs in one’s garage without a solid shield of some sort. The shield is the steel tube that runs down the middle of the spring. When the spring breaks, it's got an integral safety containment, similar to the aircraft cable that is often run through extension style springs (which are probably far more dangerous when they break, though less dangerous to service). > I’m honestly not sure why springs are common at all in this application. They're nicely matched to the load profile of the door. As the door is fully closed, the spring is exerting maximum upward force. As sections of the door transition to the horizontal track, the spring is simultaneously relaxing some, meaning it exerts around half the force when the door is halfway up and very little force as the last segment hits the turn in the track. It's a pretty elegant match of mechanism to the load profile.
• jakogut 3y ago
  > I’m honestly not sure why springs are common at all in this application. Properly adjusted springs effectively cancel out the weight of the door. This makes it easy to open and close with and without an opener, and greatly limits the danger of a door falling closed under it's own weight, which can seriously hurt someone.
  • kmoser 3y ago
    One of my garage door springs snapped unexpectedly while my housemate was opening the garage door. I'm glad nobody was under the door at the time since it slammed so hard it put a bend in the bottom section.
    • deleted 3y ago
      [deleted]
• foofie 3y ago
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• mnw21cam 3y ago
  I recently accidentally drained the battery on my car while I was fixing unrelated stuff on the door (and therefore had the door open for 3 hours). I bought a "jumpstarter kit" which is basically a 12000mAh LiIon battery (3.7V) and some electronics. It's just a little bigger than a large mobile phone, but you clip it to the car battery and it's capable of providing 12V at 600A to turn the starter motor for up to 5 seconds. That's 7.2kW from a shockingly small device. I treated it with all due respect.
  • amluto 3y ago
    Some pedantry: 1. It’s unlikely there’s power conversion circuitry in the kit. It’s almost certainly a few cells in series. 2. I’d be surprised if it can actually produce 600A at 12V. It’ll be “12V nominal” into an open circuit, which is really more like 14V for a 4-cell Li-ion setup. But even a 600 cold cranking amp lead-acid battery only supplies 7.2V at 600A.
    • mnw21cam 3y ago
      1: That's not what the manual says. But you're probably right anyway. I haven't cracked the box open to check. 2: Yes, you're right I'm sure.
• tlb 3y ago
  It’s usually a requirement that, in an emergency, you can disconnect the electric opener and open it by hand. Certainly if there’s no second door to the garage, this seems essential or you’d be trapped if power or anything in the opener fails. Springs make this possible.
• 83 3y ago
  The spring counteracts the weight of the door. In the event of motor or electricity failure a well adjusted spring/door will be easy to manually open. A direct drive/worm gear would require an uncoupling mechanism and the ability to lift the full weight of the garage door overhead to get out. Attention is required when changing these, but they really don't pose that great of a risk. I've been present when one broke, and I've changed them myself. As noted by others - the spring stays contained by the metal shaft. They really aren't worth substituting with something that has more drawbacks when a spring's lifespan is on the order of decades.