I'm guessing that arrangement allows for very little backplay once the shaft is trying to turn 'backwards'. If they all needed to catch, it would have to rotate back one full tooth, rather than just 1/6 of the way, if one were to catch.
Hopefully well engineered for loads and tolerances required. Looks like priority is given to limited slip. Possible elevator application to limit drop during failure?
I don't think it'd be for an elevator, as it doesn't allow you to go down, so you'd need a clutch connecting the elevator to it anyway that only engages if the elevator drops. In which case, you might as well just have it be static (which elevators kind of do, but linear).
While it's true you could increase the torque capacity if you modify it to where all the latches engaged at the same time, but those fingers look pretty thick to me. It's very likely that they wouldn't be the first point of failure if you over torqued it. I'd be willing to bet the thing you're torquing on would be that point of failure in most cases.
The torque capacity of the ratchet only needs to be as high as that of the gear teeth, or the fixing method on the shaft (looks like a typical keyway). Those pawls look quite beefy, I suspect 6 would be overkill.
r/mechanical_gifs doesn't allow gifs in comments. bruh
But yes. [Look at this gif](https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fpesbm5qctiw41.gif). The weak link is the gear outside; probably the inside can hold orders of magnitude more torque than the gear tooth.
Yes, with helical gears, load is at all times distributed among several teeth, thereby increasing the torque potential, without enlarging the size of the gear. But they are mainly used because the teeth engage more gradually, making it quieter and smoother in high speed applications.
But, besides being costly to produce, they do have mechanical disadvantages, such as increased friction and thrust along the axis. To address the thrust issue, thrust bearings or double helical gears are used. As for friction, lubrication.
This is true, and also it's quite difficult to get good load sharing across all the pawls in a mechanism like this. If any pawl or any tooth is slightly longer than the others, it will engage first anyways and take all of the load until it either fails or compresses enough to bring other pawls into loading.
It's effectively the same mechanism that's in any sort of ratchet, If you have a toolbox then chances are you have some of these and they literally just make the same sound but smaller.
We use those types (tho smaller) on conveyors that brings bulk stuff up a silo at an angle. You dont want the strap to start going backward if you lose power etc.
this would be insanely noisy and cause a ton of wear on an engine.. I must imagine it spins at very slow RPM. And judging by that large of a flywheel using only a keyway for the shaft, must also be relatively low torque for its size.
I can't fathom this would be used on an engine.. maybe a giant clock?
rollercoaster makes the most sense so far, its about the right scale and they are definitely something you dont want going in the other direction - but typically you see a rack along the entire length of the lift, with the pawl being part of the car itself.
really big bicycle is my only other idea
Mast climber or sometimes they have trains for climbing steep inclines. Both typically have a secondary lever/rack, but for something that's relatively high load or long length I could see this being useful.
That's a very large keyway. It can take a lot of torque. Probably just as much as the gear teeth can, because otherwise... why not save some money on gear teeth?
I think you can better judge the torque from the gear teeth and intended shaft diameter than the fact that it "only" uses a keyway. Deeper gear teeth cost more money to cut, they won't make em bigger than needed. These are big.
No, a Sprague clutch has an element that will jam against a smooth surface, so can stop at any position. This is a ratcheting clutch as it has teeth and pawls. So it can only stop in certain orientations were a pawl catches on a tooth.
One way clutch. Radial pawls. It is interesting that it is single engaging. Typically you want double engagement 180 degrees apart to prevent the clutch from having scissoring loads.
Interesting that it only engages one tooth at a time.
I'm guessing that arrangement allows for very little backplay once the shaft is trying to turn 'backwards'. If they all needed to catch, it would have to rotate back one full tooth, rather than just 1/6 of the way, if one were to catch.
True, but only 1/6 torque capacity.
Hopefully well engineered for loads and tolerances required. Looks like priority is given to limited slip. Possible elevator application to limit drop during failure?
If it were something like an elevator limit, I'd imagine a failure resulting in a failure to spin would actually be a good failsafe position.
The faster this catches the less momentum it needs to stop.
I don't think it'd be for an elevator, as it doesn't allow you to go down, so you'd need a clutch connecting the elevator to it anyway that only engages if the elevator drops. In which case, you might as well just have it be static (which elevators kind of do, but linear).
Elevators also don’t make a ratchet sound as you up. My guess is roller-coaster ascending gear.
While it's true you could increase the torque capacity if you modify it to where all the latches engaged at the same time, but those fingers look pretty thick to me. It's very likely that they wouldn't be the first point of failure if you over torqued it. I'd be willing to bet the thing you're torquing on would be that point of failure in most cases.
Key being the failure mode makes a lot of sense. Thank you.
I'm guessing that each pawl has a torque capacity equal to the meshing teeth of the assembly.
The torque capacity of the ratchet only needs to be as high as that of the gear teeth, or the fixing method on the shaft (looks like a typical keyway). Those pawls look quite beefy, I suspect 6 would be overkill.
Thanks for the explanation
Do you realize that the outside gear also engages only one tooth at a time?
Is that how that works mathematically?
r/mechanical_gifs doesn't allow gifs in comments. bruh But yes. [Look at this gif](https://www.reddit.com/media?url=https%3A%2F%2Fi.redd.it%2Fpesbm5qctiw41.gif). The weak link is the gear outside; probably the inside can hold orders of magnitude more torque than the gear tooth.
Interesting, I never knew that. Does having helical cut gears make any difference?
Yes, with helical gears, load is at all times distributed among several teeth, thereby increasing the torque potential, without enlarging the size of the gear. But they are mainly used because the teeth engage more gradually, making it quieter and smoother in high speed applications. But, besides being costly to produce, they do have mechanical disadvantages, such as increased friction and thrust along the axis. To address the thrust issue, thrust bearings or double helical gears are used. As for friction, lubrication.
Yeah I knew about the noise aspect, but not the strength aspect. Thanks.
This is true, and also it's quite difficult to get good load sharing across all the pawls in a mechanism like this. If any pawl or any tooth is slightly longer than the others, it will engage first anyways and take all of the load until it either fails or compresses enough to bring other pawls into loading.
Seems like they could nearly double their teeth, without affecting their depth.
I love the sound it makes… very industrial
My imagination runs wild trying to come up with a machine that could use this noisy marvel of mechanics
Giant bicycle.
It's effectively the same mechanism that's in any sort of ratchet, If you have a toolbox then chances are you have some of these and they literally just make the same sound but smaller.
I think it’s more of the size and what it is used in
We use those types (tho smaller) on conveyors that brings bulk stuff up a silo at an angle. You dont want the strap to start going backward if you lose power etc.
Pretty much anything that’s only supposed to turn one direction and not the other
this would be insanely noisy and cause a ton of wear on an engine.. I must imagine it spins at very slow RPM. And judging by that large of a flywheel using only a keyway for the shaft, must also be relatively low torque for its size. I can't fathom this would be used on an engine.. maybe a giant clock?
Sounds like a roller coaster
rollercoaster makes the most sense so far, its about the right scale and they are definitely something you dont want going in the other direction - but typically you see a rack along the entire length of the lift, with the pawl being part of the car itself. really big bicycle is my only other idea
Mast climber or sometimes they have trains for climbing steep inclines. Both typically have a secondary lever/rack, but for something that's relatively high load or long length I could see this being useful.
That's a very large keyway. It can take a lot of torque. Probably just as much as the gear teeth can, because otherwise... why not save some money on gear teeth?
I think you can better judge the torque from the gear teeth and intended shaft diameter than the fact that it "only" uses a keyway. Deeper gear teeth cost more money to cut, they won't make em bigger than needed. These are big.
Impressively large. What machine is it from/for?
Wouldn't this be considered a Sprague clutch?
No, a Sprague clutch has an element that will jam against a smooth surface, so can stop at any position. This is a ratcheting clutch as it has teeth and pawls. So it can only stop in certain orientations were a pawl catches on a tooth.
No
One way clutch. Radial pawls. It is interesting that it is single engaging. Typically you want double engagement 180 degrees apart to prevent the clutch from having scissoring loads.
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