EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: Ampera on February 01, 2017, 07:37:25 am
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This is more mechanical engineering than electrical engineering, but, heck, they are similar enough.
So my house is fairly old, around 100 years, which is typical for this area (Schenectady, former home of GE), and the knobs are all probably original in the downstairs floor.
Well, one of the knobs broke in a sort. While normally the latch has a spring behind it so it can push out (In order to close the door), it wasn't doing that right. Instead it
could only be convinced to move out just enough to close the door with a lot of fiddling with the knob. You can't push it closed, which is the bottom line.
So I open the lock up, and I find that instead of a single spring, which I thought might have been dislodged, it's two springs, but not in separate locations, the intended
design for that knob/lock (Warded lock) is that the two springs are right next to each other, essentially forming a longer spring, and one of the springs had turned on its
side and didn't spring all the way. Why they didn't just use one long spring, I don't know (And I am interested if there is a reason) but I finally righted it, and it works alright
now.
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Maybe 100 years ago, they didn't have the longer springs at hand and just used two springs that were available.
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Did you take photos?
I refurbished the door latch/lock mechanisms in my then 70 year old dorm room. Cleaning, polishing where movement occurs, greasing, and replacing on one of them the big leaf spring that activates the striker. Worked like new afterward.
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Are the springs different pitches/diameters? Nowadays it's fairly easy to wind a spring with variable pitch or diameter to adjust the displacement/force profile to better suit the load, but back then it may have been easier to use two separate springs.
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Are the springs different pitches/diameters? Nowadays it's fairly easy to wind a spring with variable pitch or diameter to adjust the displacement/force profile to better suit the load, but back then it may have been easier to use two separate springs.
That was another thought that has been playing on my mind since my earlier post.
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Are the springs different pitches/diameters? Nowadays it's fairly easy to wind a spring with variable pitch or diameter to adjust the displacement/force profile to better suit the load, but back then it may have been easier to use two separate springs.
No, they are identical. They aren't even very special springs, just regular spiral wire springs.
And I wish I took pictures. I'd have to unscrew it again, but maybe I will.