Automatic Transmission One-way Roller Clutch
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- เผยแพร่เมื่อ 20 พ.ย. 2020
- This educational video explains how the One-way overrunning or roller clutch works to allow rotation in one direction and prevent it in the opposite direction.
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Always great info and explanation! Keepem coming thank you.
You explained it nicely.
Great video !!!
thanks! looking at still images had me confused about how there roller works, because i thought the spring itself will cause the rotating inner part thing to stop/slowing down.
Hi! You seem to know a lot about these bearings. I have a question. I'm trying to build a racer electric road bike with a geared hub motor in front wheel. The problem is that the motor had very thick grease caused a lot of friction. I removed the grease and I put instead more racer grease that is much smoother, the problem was that the pins in the one-way bearing made noise when I rotate the hub, so I had to cut like 5mm from the spring length, and it's a normal spring not like the ones in your video. The noise disappeared after that. I tested the hub motor, it rotate much smoother and the bearing seems to work exactly like before. Do you think this is okay or should I worry about some defects that might happen? I tried first to remove the spring but I noticed that the bearing might lock itself only with one single pin, and not with all the pins, so I had to put back the springs and only shorten them a bit. Thank you very much!
The stiffness of the springs are for a particular reason. Your one way clutch could prematurely lock up with the weaker springs. I would replace the springs with the stronger ones and pack it with the thicker grease. The thinner grease will not make that much of a difference as long as you are using quality grease.
Greta explanation, I wonder if you can answer this.
I bought a Sprag from a Yamaha V-Star Starter, it is about 110mm diameter and seemed tough, but in my application on a chain driven sprocket it works great at first but slips under load in the lock direction. How much "Break away" torque can a Sprag supply vs a roller style?
The load handling capability of a sprag or roller comes down to surface or contact area. How wide is the sprag? how many sprags are in the element. In transmissions if there is a heavy duty sprag for an application all they normally did was increase the number of sprags. For your sprag are were both sprag races replaced? Some sprags come with the inner and outer race where other times the inner and or outer race are separate components. If the races are separate and they have not been replaced this could be why you are experiencing slippage.
@@DrivelineMaster it was a complete set, inner, outer, sprag holder spring and 20 elements that are 8mm wide. It worked for a while and it would get hot and then expand and freewheel
Since this was a complete unit there are typically 4 reasons for it to fail. Lack of lubrication, improper or contaminated lubrication, inferior or low quality product, or it's being overloaded by too much torque or load and the spag just can't handle the torque being applied through the application.
@@DrivelineMaster Yes I believe I overloaded it, it was designed to start a 1,100cc engine, I used it on the sprocket to drive my cv axles.
But by looking at the design of the roller, it wouldn't have slipped.
I have a question about friction in these one-way roller and and one-way sprag type clutches. There doesn't seem to be much rolling going on. This appears to be because the rollers/sprags are static (non-rolling), unlike in a regular bearing, where they roll along both the inner and outer race.
So are these (both roller and sprag type) one-way clutches just very high friction?
Thank you for any answer. I greatly appreciate it. Cheers man!
Thanks for the question. The roller clutch and sprag clutch are two different designed. Even though It's called a roller clutch it does not act like a bearing. Bearings provide a low rolling resistance between two objects, control axial and or radial loads and also help to maintain the position of the objects. These OWC's do neither. In order for a one way clutch (sometimes called an overrunning clutch) to work one of the races (inner or outer) must be held stationary while the other race tries to rotate. If the rotational race tries to rotate in the lock direction the one way mechanism kicks in and prevents rotation. If the rotational race tries to rotate in the free spinning (or overrunning) direction it will be allowed to do so by design. There is some friction that will take place during the free spinning action but the friction and rollers (or sprags) don't support any axial or radial loads like a normal bearing would. Additionally these are normally saturated in automatic transmission fluid. Write again if you need further explanation or have a followup question.
@@DrivelineMaster Thanks for the answer man. I really appreciate it.
Yeah, I was definitely referring to when they are in the "free spinning" mode. I probably should have been more specific lol.
The reason I was bringing up friction is because I was thinking of a bicycle ratcheting freewheel and the fact that they are in "free spinning" mode quite a lot (whenever someone isn't pedaling or pedaling slower than the bicycle is moving, as well as when someone is pedaling backwards).
And since you so kindly offered to answer a followup question with further explanation, I will take you up on your offer!
I guess what I'm wondering is the difference in function and application between these roller (or sprag) clutches and the aforementioned ratcheting-type freewheels (in general, not limited to bicycles, that was just an example).
Are they interchangeable? Could you use a roller (or sprag) clutch on a bicycle and if so would there be much more friction than the ratcheting-type freewheel and if so would it be too much to make it worthwhile - or for that matter would it even function? Are there any other devices or systems where the roller (or sprag) clutch could replace the ratcheting-type freewheel mechanism?
And the reverse as well, could you use a ratcheting-type "clutch" (if you would call it that - and I'm not talking specifically about bicycle freewheels - I'm referring to any ratcheting-type clutch mechanism) in a device or system typically serviced by roller or sprag clutches? If so, what kind of device or system? Would there be a reduction in friction? What would be the drawbacks (or benefits) of such a replacement mechanism?
I realized I just asked like 10 questions. Please forgive me. I just find devices and mechanisms like this very fascinating and I am forever grateful for your response.
Thanks again mate. Cheers!
@@DrivelineMaster Thanks again for the reply. That really helps in understanding that they aren't meant to support loads - whether axial or radial - or at least not to the extent of bearings. That definitely clears some things up for me conceptually. Again I appreciate you taking the time to reply.
I guess my final question would be this.
Suppose we had two bars that are extremely lightweight and/or completely supported by bearings at either end - either way the axial and radial load forces are subtracted from the situation - the only force that matters is the friction on the mechanism in the middle.
The mechanism(s) in the middle are the following:
One bar is going through - and attached to the inner race of - a roller clutch positioned in the middle. The outer race is held stationary.
The exact same setup goes for the other bar - except it is a ratcheting freewheel mechanism instead of a roller clutch mechanism.
They are both spinning in the free-spinning direction.
What is the difference in friction between the free-spinning-bar-roller clutch mechanism setup and the free-spinning-bar-ratcheting freewheel mechanism setup?
I guess I do have one more question. If you have time and do answer, I do kindly ask that you treat this as a separate inquiry unrelated to the previous question.
In general, how significant is friction in roller clutches in the free-spinning direction? I ask this because the rollers don't actually appear to do very much rolling when the roller clutch is in the free-spinning direction (beyond the fraction of a revolution that they travel in their channel of course). They seem to do more sliding - as opposed to rolling - when the roller clutch is in the free-spinning direction.
This really gets down to the nuts and bolts of why I was confused in the first place. Is the lubricant - transmission fluid or otherwise - significant enough to overcome this friction when in the free-spinning direction? And by "significant enough" I mean to ask is it significant enough to make friction an insignificant issue?
Thank you again for your replies. I realize my inquiry may be somewhat lengthy. I genuinely appreciate your responses and can't wait to hear back.
Thanks again, again. Cheers mate.
If I understand your questions really come down to the amount of friction that takes place during the free spinning direction. The first question compares a ratcheting design which we call a "Diode" clutch and a roller clutch. The second question is simply looking for the friction on the roller clutch. And yes, the rollers in the roller clutch don't really roll or support a load like a typically roller bearing would. I can honestly say that these are truly engineering questions that I'm not qualified to answer. My guess is that if you had the two setups to test that you could use a spring scale or dial type torque wrench to measure the rotational force for a comparison. You could also test various lubricants at this time. I suspect the surface area of contact along with the surface polish and metal hardness along with the lubricant all play a factor in the coefficient of friction. Sorry I don't have answers for you.
@@DrivelineMaster That answer was more than satisfactory. I definitely have a complete conceptual grasp of the differences now.
Thank you for taking the time to have this back and forth with me. I realize that you are probably a busy gentleman and that you didn't have to spend time helping me on my continuing journey of education in these matters.
There is absolutely nothing to be sorry for. Your information has successfully informed me of this marvelous device's role vs that of other somewhat similar mechanisms.
I come from a computer engineering background primarily, but I have been dabbling in the mechanical arts as a side-hobby/side-job for decades as well.
Thank you again sir for your assistance and exchange. Take care mate.
Cheers!
hello, what type is it? i am looking for this kind one way clutch..
This is from the inside of an automatic transmission torque converter. One Way roller and sprag clutches are frequently used inside automatic transmissions.
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