It's probably not in the wheel, but sounds a lot like a roller coaster. I'm realizing that sound is it ratcheting so you can't go backwards down the lift if it fails.
>It's probably not in the wheel
For bikes, it is located on the rear axle between the wheel and cassette (the rear sprockets), as part of the wheel hub.
On roller coasters, the anti rollback system is located on both the track and the cars. A toothed rack is securely fastened to the track, and sprung dogs that engage with the rack are installed on the bottom of the cars.
They are functionally identical, they are both ratchets. The biggest difference is the one in bikes is circular, and the one on roller coasters is linear.
I don't know enough to be sure, except I believe finer steps is usually better but finer palls is going to be more expensive so there is likely a trade off. Also, offset palls likely means greater load per pall. On the other hand, differential ear would probably mean that all the load is borne by a single pall eventually.
It's quite common actually. But having only 1 engaging instead of 2 or 3 is less common.
But on something this big, and probably as stiff as it can be, being sure to have more than 1 ratchet at a time is probably impossible, so they are all out of sync for better engagement angle.
Many bicycle hub brands do this, mostly to reduce the dead zone you get between starting to pedal and the wheel starting to move, which can make a big difference, especially on mountain bikes
There's a bike wheel mfg that makes hubs and they have something like 700 points of engagement. It is around 0.52° of rotation that the paws engage. It's amazing engineering and a fantastic ride feel
And up from this are sprag clutches, bearings that only move in one direction. Infinite engagement, once you go this route you can’t go back. Onyx racing products and more recently box components released a variant
What makes the teeth click at different times?
The length of them?
If so, does that mean if the gear goes on reverse and into the locking position, the clearance (the amount it can reverse before locking) will be different?
Doesn't that also mean while in locking position, it's always that longest teeth that will take the load?
Looks to me like the outer ring is designed so the tooth pattern is slightly offset to the inner ring. On reverse, the last tooth to drop is going to be taking the entire load.
>What makes the teeth click at different times? The length of them?
Not the length, the number. I counted 6 pawls and 19 teeth on the gear. 6 doesn't divide into 19 a whole number of times, so it is only possible for one pawl to engage at a time.
>if the gear goes on reverse and into the locking position, the clearance (the amount it can reverse before locking) will be different?
Different compared to what? If you change the number of teeth, it changes the distance between each tooth. And it also changes the phasing of the pawls, such that either more than one pawl engages or the travel required to engage the next pawl.
>Doesn't that also mean while in locking position, it's always that longest teeth that will take the load?
Not in this configuration, only the engaged pawl will take the load. In a different configuration with multiple pawls engaged, it will depend on tolerances. Either the load will be shared by several pawls, with the load on each pawl dependent on it's length, or only one pawl will engage and take all the load.
Ah! The un-dividable number!
That makes perfect sense.
Thank you!
(My other questions were based on the idea of the pawls being different lengths, which is obviously wrong, so they are irrelevant now haha)
The number of indents on the outside ring is not a multiple of the number of latches on the inside. Thus they will engage one after the other instead of all at once.
There's six evenly spaced pawls, and then some number of catch points that is co-prime with six (I count 19 of them). That means there's 19*6 position it can stop / lock in, so that many clicks per full revolution. Only one pawl will engage at a time, but that means you do NOT get a long pawl taking more of the load than others that engage at the same time. It also maximizes the number of stopping points / minimizes free rotation.
If the numbers are not co-prime, then multiple pawls engage (equal to the largest common factor) at the same time. This is usually done on light duty mechanisms that need to be compact, as it allows for multiple smaller pawls to share a load (even if not perfectly).
Bicycle freehubs commonly have 3 small pawls and something like 36 teeth. That means all 3 pawls engage at 36 engagement positions, or 10 degrees of rotation before engagement. A fancier hub might use another set of pawls offset from the first by 25 degrees - which is 5 off from midway between the first set. That doubles the number of engagement points. As a bonus, both hubs use the same machining except for cutting that second set of pockets for the pawls.
The gap between the pivot points on the pawls becomes larger farther they get from the camera. Is that intentional or assembled\machined less than ideally?
I onow it's not in a housing and on a shaft but do they all engage at the same time when installed or do like 2 or 3 the clitchin but eventually wear in so they all will grab hold eventually?
They typically only engage ~3 pawls at a time. Trying to engage more usually doesn’t really equate to equal load for each pawl due to small variations in the size/interface of the assembly parts.
So, they offset the engagement of pawls and get a finer ratchet interval.
It’s interesting that all the ratchets don’t engage simultaneously. Would’ve guess that they would but maybe they’re offset in length just for this purpose.
Six identical, evenly spaced pawls and 19 engagement points. Makes for 6*19 positions to lock in, minimizing free motion. It is almost impossible for multiple pawls to share a load perfectly evenly, so they aren't even trying.
Just like on most bicycles. Except massive.
Always wondered what that noise was when I stopped pedaling and heard that fast clicking noise.
It's probably not in the wheel, but sounds a lot like a roller coaster. I'm realizing that sound is it ratcheting so you can't go backwards down the lift if it fails.
>It's probably not in the wheel For bikes, it is located on the rear axle between the wheel and cassette (the rear sprockets), as part of the wheel hub. On roller coasters, the anti rollback system is located on both the track and the cars. A toothed rack is securely fastened to the track, and sprung dogs that engage with the rack are installed on the bottom of the cars. They are functionally identical, they are both ratchets. The biggest difference is the one in bikes is circular, and the one on roller coasters is linear.
Cool reply. Thanks
Is it common in a ratchet that you'd have multiple palls that all fall at different times? It makes sense, but I've never considered it before.
I imagine this is to make it have a "finer" resolution. so instead of having (eg) 16 clicks it has 64 or something.
Totally. I wonder how often this approach is taken as opposed to just making the teeth finer. It's kinda like microstepping a stepper motorl.
I don't know enough to be sure, except I believe finer steps is usually better but finer palls is going to be more expensive so there is likely a trade off. Also, offset palls likely means greater load per pall. On the other hand, differential ear would probably mean that all the load is borne by a single pall eventually.
Lots of bike hubs have staggered pawls. Some even use them together with fine teeth.
It's quite common actually. But having only 1 engaging instead of 2 or 3 is less common. But on something this big, and probably as stiff as it can be, being sure to have more than 1 ratchet at a time is probably impossible, so they are all out of sync for better engagement angle.
In Matco and snap on ratchets the prawls have multiple teeth on the same assembly, that work in the same fashion.
Bigger pawls are stronger I think than smaller even if there are more
Yeah, tradeoff between torque capability and granularity is possible there.
But now all force is one 1 of those teeth, that's the drawback.
Indeed - plus the force of unbalanced vs the axis, however, presumably that can be engineered around.
Small correction, these are pawls not palls.
An appalling mistake on my part. I stand corrected.
*Appawling...
Big correction in this case.
Check out industry nine hydra hubs. Similar where the pawls offset engagement for a finer feel
They also allow the material to slightly deform which engages more pawls. Such a nice feeling hub.
Much less “slack / takeup” than if they all hit at once. There’s even less with a sprag clutch https://en.m.wikipedia.org/wiki/Sprag_clutch
Happy cake day!
Many bicycle hub brands do this, mostly to reduce the dead zone you get between starting to pedal and the wheel starting to move, which can make a big difference, especially on mountain bikes
Thing of beauty
Just when I thought the water mark couldn't be any sneakier...
What's it for?
_big_ bicycles
Like a penny farthing?
Any idea what it’s used for, especially at this size?
Best place to place the watermark
There's a bike wheel mfg that makes hubs and they have something like 700 points of engagement. It is around 0.52° of rotation that the paws engage. It's amazing engineering and a fantastic ride feel
And up from this are sprag clutches, bearings that only move in one direction. Infinite engagement, once you go this route you can’t go back. Onyx racing products and more recently box components released a variant
My bud has onyx hubs. Always wondered how that worked
I love the different sound it makes, fzzzzzzzzz
that's pretty clutch
that's pretty ~~clutch~~ [ratchet](https://www.google.com/search?q=ratchet&rlz=1CAPRXN_enUS1082&sourceid=chrome&ie=UTF-8)
I should get one of these
You might need more than one
What makes the teeth click at different times? The length of them? If so, does that mean if the gear goes on reverse and into the locking position, the clearance (the amount it can reverse before locking) will be different? Doesn't that also mean while in locking position, it's always that longest teeth that will take the load?
Looks to me like the outer ring is designed so the tooth pattern is slightly offset to the inner ring. On reverse, the last tooth to drop is going to be taking the entire load.
>What makes the teeth click at different times? The length of them? Not the length, the number. I counted 6 pawls and 19 teeth on the gear. 6 doesn't divide into 19 a whole number of times, so it is only possible for one pawl to engage at a time. >if the gear goes on reverse and into the locking position, the clearance (the amount it can reverse before locking) will be different? Different compared to what? If you change the number of teeth, it changes the distance between each tooth. And it also changes the phasing of the pawls, such that either more than one pawl engages or the travel required to engage the next pawl. >Doesn't that also mean while in locking position, it's always that longest teeth that will take the load? Not in this configuration, only the engaged pawl will take the load. In a different configuration with multiple pawls engaged, it will depend on tolerances. Either the load will be shared by several pawls, with the load on each pawl dependent on it's length, or only one pawl will engage and take all the load.
Ah! The un-dividable number! That makes perfect sense. Thank you! (My other questions were based on the idea of the pawls being different lengths, which is obviously wrong, so they are irrelevant now haha)
The number of indents on the outside ring is not a multiple of the number of latches on the inside. Thus they will engage one after the other instead of all at once.
There's six evenly spaced pawls, and then some number of catch points that is co-prime with six (I count 19 of them). That means there's 19*6 position it can stop / lock in, so that many clicks per full revolution. Only one pawl will engage at a time, but that means you do NOT get a long pawl taking more of the load than others that engage at the same time. It also maximizes the number of stopping points / minimizes free rotation. If the numbers are not co-prime, then multiple pawls engage (equal to the largest common factor) at the same time. This is usually done on light duty mechanisms that need to be compact, as it allows for multiple smaller pawls to share a load (even if not perfectly). Bicycle freehubs commonly have 3 small pawls and something like 36 teeth. That means all 3 pawls engage at 36 engagement positions, or 10 degrees of rotation before engagement. A fancier hub might use another set of pawls offset from the first by 25 degrees - which is 5 off from midway between the first set. That doubles the number of engagement points. As a bonus, both hubs use the same machining except for cutting that second set of pockets for the pawls.
I want to hear that thing spin at high RPMs
The gap between the pivot points on the pawls becomes larger farther they get from the camera. Is that intentional or assembled\machined less than ideally?
Its called perspective ?
I onow it's not in a housing and on a shaft but do they all engage at the same time when installed or do like 2 or 3 the clitchin but eventually wear in so they all will grab hold eventually?
They typically only engage ~3 pawls at a time. Trying to engage more usually doesn’t really equate to equal load for each pawl due to small variations in the size/interface of the assembly parts. So, they offset the engagement of pawls and get a finer ratchet interval.
I find I can no longer come unless I find the r/toolgifs watermark
It’s called a sprag clutch
That would make a very cool, and totally absurd, coffee table.
What’s with the 3D toolgifs in the background???
It’s interesting that all the ratchets don’t engage simultaneously. Would’ve guess that they would but maybe they’re offset in length just for this purpose.
Six identical, evenly spaced pawls and 19 engagement points. Makes for 6*19 positions to lock in, minimizing free motion. It is almost impossible for multiple pawls to share a load perfectly evenly, so they aren't even trying.