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Re: centrifigal clutch operation
Re: centrifigal clutch operation -- komet99	Post Reply	Top of thread	Forum

Posted by: randykimball ® 04/11/2007, 16:29:47 Author Profile eMail author Edit

Dale, You can reduce counter spring tension. You can increase the mass of the throw weights. You can increase the leverage the throw weights have on the disk tension (modify the weight levers pivot point location)(provided there are any). I would NOT decrease the clutch disk size, this would reduce grip... something you do not want to do. (You can end up with a clutch that won't slip when you need it to) The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

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Re: Re: centrifigal clutch operation
Re: Re: centrifigal clutch operation -- randykimball	Post Reply	Top of thread	Forum

Posted by: komet99 ® 04/11/2007, 16:34:25 Author Profile eMail author Edit

If I reduce clutch surface area, doesnt that put the same force on less area, which would make it slip less. I have already remove one disc of the clutch to see what happens. The clutch worked fine but I had too much spring pressure. So my next move would be to find a clutch spring with less tension. Dale

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Re: Re: Re: centrifigal clutch operation
Re: Re: Re: centrifigal clutch operation -- komet99	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 04/11/2007, 21:18:17 Author Profile eMail author Edit

In general the following is true T = P*u*n*r Where: P = Total applied force of disk against friction pad (Lbs) Springs? u = Coefficient of friction n = Number of slipping surfaces r = mean radius of disk(s)inches T = Torque Capacity (Clutch)lb-in So, if you increase P,u,n, or r you have more Torque capacity. All you realy need is to reduce the slippage between the friction pads and the disk. At some point if there is not any slippage then you are doing all you can. To me, the answer may be in the mechanism that applies the force P at the right rpm and torque for your particular motor configuration. Reference: Kent's Mechanical Engineers Handbook, Design and Production Volume, Twelfth Edition Modified by Kelly Bramble at Wed, Apr 11, 2007, 21:19:53

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Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: centrifigal clutch operation -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 04/12/2007, 17:27:31 Author Profile eMail author Edit

I think that P (Total applied force of disk against friction pad (Lbs)) can be further defined as P = RPM * C Where: RPM = Revolutions per minute C = Constant dependant on RPM C is derived from the characteristics of the centifugal clutch

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Re: Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: Re: centrifigal clutch operation -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: komet99 ® 04/12/2007, 17:49:00 Author Profile eMail author Edit

To tell you more information. The clutch is located on the axle. With the expansion chamber manufacturers we have working with us to get more horsepower, the racers must engage the clutch at 10,800 engine rpm. Now when I start a race, it is from a dead stop. So the motor revs to 10,800 rpm untill the axle speed catches up with the clutch speed which is around 50-55 mph. This is the time that I want to reduce. Some people told me the only way to reduce this time is to make more horsepower. Completely understandable----but I am limited to a rule book at witch I am to the limits now. So I must move elsewhere to gain advantages. Dale

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Re: Re: Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: Re: Re: centrifigal clutch operation -- komet99	Post Reply	Top of thread	Forum

Posted by: randykimball ® 04/13/2007, 08:48:02 Author Profile eMail author Edit

Are your throw weights on lever arms? If so, if you lenghtn the arms slightly you will put more clamping force on the disk stack. This will greatly increase your grip and reduce the clutch grab time. Do this without reducing the amount of disk surface. More disks means more grip, more surface means more grip... with more compression force from the increased leverage from longer throw weight arms. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

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Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation -- randykimball	Post Reply	Top of thread	Forum

Posted by: komet99 ® 04/13/2007, 09:35:33 Author Profile eMail author Edit

No they are not on lever arms. The weights slide on a wedge as clutch rpm increases. I currently have tungsten secondary weights installed in the clutch. I am looking at putting rhenium secondary weights as a replacement for more weight. I just dont want to damage the disc with to much force. Is there anyone who makes a stronger friction material?? Take a look at kartclutches dot com. got to the axle clutch link and there is a breakdown of the clutch I am using. Dale Admin: Changed url with the word "dot" Modified by Administrator at Fri, Apr 13, 2007, 09:39:31

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Re: Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation -- komet99	Post Reply	Top of thread	Forum

Posted by: Kelly Bramble ® 04/13/2007, 09:47:15 Author Profile eMail author Edit

Other considerations; Mass of the drive train: The more the cumulative components weight, the more horse power it will take to spin them up to the desired angular velocity. However, the more mass you have, the more energy it will take to slow the drive train down, thus more initial acceleration. Bearings: These need to be low friction, low mass, and aligned properly. Do you have performance charts/curves (test data) of the clutch(s) that you are using? This is the only way to be objective about your clutch selection and use. Looking at the design is interesting and fun, however not revealing. Modified by Kelly Bramble at Fri, Apr 13, 2007, 09:50:22

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Re: Re: Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation -- Kelly Bramble	Post Reply	Top of thread	Forum

Posted by: CCR5600Design ® 04/20/2007, 15:37:05 Author Profile eMail author Edit

I am wondering... Do your class rules require you to run an axle-mounted clutch? Since the clutch does not engage quickly enough for you due to the slower axle speed as compared to crankshaft RPM, why not use a crankshaft or jackshaft mounted clutch which will engage quicker? Ron "What we need are more people who specialize in the impossible." - Theodore Roethke

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Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation
Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: centrifigal clutch operation -- CCR5600Design	Post Reply	Top of thread	Forum

Posted by: komet99 ® 04/20/2007, 16:10:19 Author Profile eMail author Edit

No, the rules say the clutch must not leak. So I chose the axle clutch. Tests have proven that it is easier to rotate the axle clutch than any other clutch available due to the gear ratio. I have reduced spring pressure and installed new clutch discs for another test at the next race. Bones

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