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Forums13
Topics6,521
Posts36,906
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Most Online117 Jan 16th, 2020
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#8028 - 08/09/13 04:36 AM
Re: Why use breaks on geared traction machines
[Re: RCD]
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Joined: Aug 2011
Posts: 563
uppo72
addict
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addict
Joined: Aug 2011
Posts: 563
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So everyone knows that a worm gear will not hold a load but no one seems to know why. Oh we do know why mate think about it. If you disconnected the worm gear from the brake drum, with the car still attached via the ropes, unless the car/cwt are balanced perfectly in the shaft the car will roll up because the cwt is generally 40 to 50% heavier by design. if the ropes were removed from the traction sheave then there is no load and therefore the no movement on the sheave/crownwheel/worm gear. Hope this clears it up for you. THIS is how we know your theory doesn't work.
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#8033 - 08/09/13 12:16 PM
Re: Why use breaks on geared traction machines
[Re: uppo72]
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Joined: Feb 2013
Posts: 761
john jay
old hand
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old hand
Joined: Feb 2013
Posts: 761
ohio
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we all know why, it was made very clear, during our lengthy apprenticeship, we could let you in on the secret, but since you have never worked in the business it would be a waste of a good secret.
Last edited by john jay; 08/09/13 12:17 PM.
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#8043 - 08/10/13 01:14 AM
Re: Why use breaks on geared traction machines
[Re: RCD]
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Joined: Jul 2013
Posts: 134
traction
member
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member
Joined: Jul 2013
Posts: 134
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Let's take a look at this winch in this youtube video [link below](way to small to lift an elevator but still the same principle). If I were to use this winch in a dumbwaiter to lift a load of 100lbs (no counterweight / lifting straight up) are you saying that the 100lbs load would turn the input (the worm) and descend? https://www.youtube.com/watch?v=LUYqVE1R2KA Theory and reality are two different things. You can't tell untill you try it. There are safety codes written because theory doesn't equal safety.
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#8046 - 08/10/13 01:55 AM
Re: Why use breaks on geared traction machines
[Re: RCD]
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Joined: Aug 2011
Posts: 563
uppo72
addict
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addict
Joined: Aug 2011
Posts: 563
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Let's take a look at this winch in this youtube video [link below](way to small to lift an elevator but still the same principle). If I were to use this winch in a dumbwaiter to lift a load of 100lbs (no counterweight / lifting straight up) are you saying that the 100lbs load would turn the input (the worm) and descend? https://www.youtube.com/watch?v=LUYqVE1R2KA Firstly I would assume that when it states its 'self locking' (depending on any 'locking feature' on the worm gear ie caravan winders that have that clicking sound which is a reverse lock), I would imagine it has a load maximum and that it depends on runaway characteristics as well ie if the load is down hill. So if the winch is over loaded then it can runaway. Remember to that a dumbwaiter is also an 'old style' hoist ie a drum drive system which also has a braking system either a drum brake on the old units or a disc brake on the new units like a overhead crane motor.
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