New Torque Converter Design
11-19-2002 | 03:21 PM
#16
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From: Raleigh, NC
Re:New Torque Converter Design
Don,<br><br>I see the point that you're trying to make, but I have to say that you're thinking is backwards. If you're reasoning were in fact true then one disk clutches would be the rave (a one disk OD clutch would never have a chance), as would ultra skinny bicycle tires on on high powered dragsters and the like. You're right that more surface area spreads the load, but that's a good thing, not a bad one. It eliminates a small area from quickly becoming overloaded and cuts down on heat and wear. This is the exact reason that adding area for a fixed normal force will effectively increase the coefficient of friction in a lab test. A "grippy" material such as a brake or clutch disk, and especially rubber, show good curves when looking at increased friction vs. increased area. In a multidisk clutch state, the load is evenly distributed over each disk, so each single disk only sees a fraction of the total load. More surface area is almost never a bad thing when talking about power transmission if the space constraints will allow it.<br><br>Ironman, <br><br>heat in a dragster tire is a good thing, not a bad one. The sole reason for long smokey burnouts is to get slicks warm and stick for increased traction. The more area you can get on the racetrack the faster you're going to be... no disputing it. Treads on tires are nothing but an imparement of traction to cars and trucks, but are essentials for wet driving. Trust me that friction (traction) is increased.<br><br>John
11-19-2002 | 03:24 PM
#17
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From: Thornton, COLORADO
Re:New Torque Converter Design
We brought this info to help people see kind of what we do. The work shown is just a start of more we would like to bring out for people to see. Please have a open mind and maybee we can show some new things. We learn new things all the time also. Without that mind set this converter would not be on the market. Thanks for the time!!<br><br>Don ATS
11-19-2002 | 03:39 PM
#18
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From: In the Shop
Re:New Torque Converter Design
[quote author=dramer link=board=7;threadid=7241;start=0#69459 date=1037737093]<br>Don M the clutch plates are cut with a lazer. Again new tech!<br><br>Don ATS<br>[/quote]<br><br>Do you mean a laser? Just ribbbing you Man. I make spelling errors from time to time too. We used a laser from <br>Oxford lasers on a few sets of multi-hole injectors back last winter when starting up the process. Andrew Web, the main man over there can get you hooked up with top notch laser machining.<br><br>Looking at the picture I see a distinct radius cut like one left from a small diameter end mill. Is the laser not CNC controlled? It seems to be a slight program error if so.<br><br>Hang on I will show you what Im talking about in a picture.<br><br>Don~<br><br>
11-19-2002 | 04:02 PM
#19
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From: In the Shop
Re:New Torque Converter Design
[quote author=banshee link=board=7;threadid=7241;start=15#69462 date=1037737314]
Don,
I see the point that you're trying to make, but I have to say that you're thinking is backwards. If you're reasoning were in fact true then one disk clutches would be the rave (a one disk OD clutch would never have a chance), as would ultra skinny bicycle tires on on high powered dragsters and the like. You're right that more surface area spreads the load, but that's a good thing, not a bad one. It eliminates a small area from quickly becoming overloaded and cuts down on heat and wear. This is the exact reason that adding area for a fixed normal force will effectively increase the coefficient of friction in a lab test. A "grippy" material such as a brake or clutch disk, and especially rubber, show good curves when looking at increased friction vs. increased area. In a multidisk clutch state, the load is evenly distributed over each disk, so each single disk only sees a fraction of the total load. More surface area is almost never a bad thing when talking about power transmission if the space constraints will allow it.
Ironman,
heat in a dragster tire is a good thing, not a bad one. The sole reason for long smokey burnouts is to get slicks warm and stick for increased traction. The more area you can get on the racetrack the faster you're going to be... no disputing it. Treads on tires are nothing but an imparement of traction to cars and trucks, but are essentials for wet driving. Trust me that friction (traction) is increased.
John
[/quote]
John,
Actually single disks are the rave in torque convertors and nearly all dry clutches, heck even brake pads are a single disk-so to speak. Coefficient of friction is actually not the same for any material as the clamping force is raised higher.
While working on my latest clutch design I tried several types of materials, with differing coefficients of friction. The best one for slipping and being able to regrab was sintered iron. It would really slip bad at high torque loads when cold, but once it warmed up good it would grab. Much like brake pad material. The brass/ceramics we tried had great holding ability in static form, but if you slipped them they could not re-grab as well. The Kevlar and the carbon fibre both were the worse in holding anything. This, I believe had more to do with total surface area of the material than anything else.
Your formula above is not the same one I was taught either.
Mine goes like this:
The coefficient of friction (u) is a number that is the ratio of the resistive force of friction (Fr) divided by the normal or perpendicular force (Fn) pushing the objects together. It is represented by the equation:
u = Fr / Fn.
I stated earlier in my post that the larger surface area can cut down wear, but at the same time explained that wear cannot occur without slippage. Its just plain and simple. If the clutch stays stuck, the heat and wear you speak of cant happen.
Don~
I wanted to add that, yes, OD clutchs do need more than one disk...they do slip and the extra material is needed to cut wear down. In a TQ convertor you dont want slippage or should not have any, unless the clutchs are inherently slipping from too much tq applied to a system that cant handle the twisting force. Additional line pressure or clamp force and moderate applications of friction material will raise the tq capacity of the design. A heavy factor of surface area alone can reduce the holding ability of the tq convertor if the application is not balanced and the available pressure per square inch is too low. You can get increased slippage, more wear, and more heat.
Don~
Don,
I see the point that you're trying to make, but I have to say that you're thinking is backwards. If you're reasoning were in fact true then one disk clutches would be the rave (a one disk OD clutch would never have a chance), as would ultra skinny bicycle tires on on high powered dragsters and the like. You're right that more surface area spreads the load, but that's a good thing, not a bad one. It eliminates a small area from quickly becoming overloaded and cuts down on heat and wear. This is the exact reason that adding area for a fixed normal force will effectively increase the coefficient of friction in a lab test. A "grippy" material such as a brake or clutch disk, and especially rubber, show good curves when looking at increased friction vs. increased area. In a multidisk clutch state, the load is evenly distributed over each disk, so each single disk only sees a fraction of the total load. More surface area is almost never a bad thing when talking about power transmission if the space constraints will allow it.
Ironman,
heat in a dragster tire is a good thing, not a bad one. The sole reason for long smokey burnouts is to get slicks warm and stick for increased traction. The more area you can get on the racetrack the faster you're going to be... no disputing it. Treads on tires are nothing but an imparement of traction to cars and trucks, but are essentials for wet driving. Trust me that friction (traction) is increased.
John
[/quote]
John,
Actually single disks are the rave in torque convertors and nearly all dry clutches, heck even brake pads are a single disk-so to speak. Coefficient of friction is actually not the same for any material as the clamping force is raised higher.
While working on my latest clutch design I tried several types of materials, with differing coefficients of friction. The best one for slipping and being able to regrab was sintered iron. It would really slip bad at high torque loads when cold, but once it warmed up good it would grab. Much like brake pad material. The brass/ceramics we tried had great holding ability in static form, but if you slipped them they could not re-grab as well. The Kevlar and the carbon fibre both were the worse in holding anything. This, I believe had more to do with total surface area of the material than anything else.
Your formula above is not the same one I was taught either.
Mine goes like this:
The coefficient of friction (u) is a number that is the ratio of the resistive force of friction (Fr) divided by the normal or perpendicular force (Fn) pushing the objects together. It is represented by the equation:
u = Fr / Fn.
I stated earlier in my post that the larger surface area can cut down wear, but at the same time explained that wear cannot occur without slippage. Its just plain and simple. If the clutch stays stuck, the heat and wear you speak of cant happen.
Don~
I wanted to add that, yes, OD clutchs do need more than one disk...they do slip and the extra material is needed to cut wear down. In a TQ convertor you dont want slippage or should not have any, unless the clutchs are inherently slipping from too much tq applied to a system that cant handle the twisting force. Additional line pressure or clamp force and moderate applications of friction material will raise the tq capacity of the design. A heavy factor of surface area alone can reduce the holding ability of the tq convertor if the application is not balanced and the available pressure per square inch is too low. You can get increased slippage, more wear, and more heat.
Don~
11-19-2002 | 04:05 PM
#20
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Joined: Jun 2002
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From: In the Shop
Re:New Torque Converter Design
[quote author=dramer link=board=7;threadid=7241;start=0#69459 date=1037737093]<br>Don M the clutch plates are cut with a lazer. Again new tech!<br><br>Don ATS<br>[/quote]<br><br>Here is the picture of the radius cuts I was speaking of Don. They look like a round end mill made them when you observe the rounded areas highlighted.<br><br>Don~
11-19-2002 | 04:37 PM
#21
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Joined: Jul 2002
Posts: 846
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From: Raleigh, NC
Re:New Torque Converter Design
Don, <br><br>It's the same exact formula!<br><br>what i listed: Ff=mu*normal force <br><br>what you listed: u = Fr / Fn.<br><br>Now, multiply both sides of your equation by the normal force (Fn) and you get my equation!! Voila!! Simple algebra 
<br><br>Single disks may the the rave for a dry clutch, but TCs are not dry, they are oil bathed. The multi clutch "idea" is shared among most high performance clutch applications to incrase clamping power without the need of super high clamping force (via spings, hydraulic line pressure, etc). The multidisk clutches used for sled pulling (as offered by Enterprise Engine, etc) are on this same principle... they offer superior holding power, the ability to slip somewhat (the increased area will aid in heat dissipation) and having all that without having to have the legs of an NFL offensive lineman to push the clutch pedal in. I think you're stuck on the idea of increasing the area of one clutch disk only... remember, that all of the disks on the multidisk clutch are splined to the shaft... that's the key! I don't know how else to explain it without getting into a long math breakdown.<br><br>I will agree that coefficient of friction is hardly ever constant and depends on numerous things such as temp, exposed area, pressure, etc. It's a highly dynamic value, and that's the reason you can't go look in a book to get a value for rubber or sintered iron, or whatever. At best you'll get a wide range of possibles. <br><br>John
<br><br>Single disks may the the rave for a dry clutch, but TCs are not dry, they are oil bathed. The multi clutch "idea" is shared among most high performance clutch applications to incrase clamping power without the need of super high clamping force (via spings, hydraulic line pressure, etc). The multidisk clutches used for sled pulling (as offered by Enterprise Engine, etc) are on this same principle... they offer superior holding power, the ability to slip somewhat (the increased area will aid in heat dissipation) and having all that without having to have the legs of an NFL offensive lineman to push the clutch pedal in. I think you're stuck on the idea of increasing the area of one clutch disk only... remember, that all of the disks on the multidisk clutch are splined to the shaft... that's the key! I don't know how else to explain it without getting into a long math breakdown.<br><br>I will agree that coefficient of friction is hardly ever constant and depends on numerous things such as temp, exposed area, pressure, etc. It's a highly dynamic value, and that's the reason you can't go look in a book to get a value for rubber or sintered iron, or whatever. At best you'll get a wide range of possibles. <br><br>John
11-19-2002 | 04:56 PM
#23
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From: In the Shop
Re:New Torque Converter Design
John, if the disks are connected through a common shaft the coefficient of friction is not the same for both sides of the disk. So the formula you posted would/could not work. Coefficient of friction is lower or higher depending not only on pressure applied but on temperature too. The disk side closer to the piston would have a different u than the side next to the plate between disks.<br><br>Don~
11-19-2002 | 05:14 PM
#25
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From: In the Shop
Re:New Torque Converter Design
John and everyone else,
A quick and easy way to understand how surface area, friction material, and total clamp load or pressure is easily explained like this:
Your older and less advanced drum brakes on the rear axle of a car have much more surface area and less clamping force than the newer rear brakes that are of the disk type. The newer disk type brakes have much less surface area and more clamping force and work much better than the old technology drum brakes even with all their surface area.
I had an old 67 Mustang that even had drum brakes in the front and getting that thing to stop fast was impossible. After a quick disk brake conversion on the front I had much less total pad or shoe area, but the thing would stop very well. This was because of the increased clamp load that was not spread out over a large area and the friction material was better. Higher "u" or coefficient of friction.
Don~
A quick and easy way to understand how surface area, friction material, and total clamp load or pressure is easily explained like this:
Your older and less advanced drum brakes on the rear axle of a car have much more surface area and less clamping force than the newer rear brakes that are of the disk type. The newer disk type brakes have much less surface area and more clamping force and work much better than the old technology drum brakes even with all their surface area.
I had an old 67 Mustang that even had drum brakes in the front and getting that thing to stop fast was impossible. After a quick disk brake conversion on the front I had much less total pad or shoe area, but the thing would stop very well. This was because of the increased clamp load that was not spread out over a large area and the friction material was better. Higher "u" or coefficient of friction.
Don~
11-19-2002 | 05:22 PM
#26
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From: In the Shop
Re:New Torque Converter Design
[quote author=Scotty link=board=7;threadid=7241;start=15#69522 date=1037743724]
I am getting the idea that this does not apply to my manual transmission.
[/quote]
It does Scotty. Your Southbend clutch is using a material with a higher "U" and the clamp load is increased not by a stiffer spring, but applying more pressure from having the pressure ring machined to apply the most clamping force it can on its bell curve. The same thing is done by some tq convertor/transmission builders, increasing clamp load by bumping line pressure and using a friction material with higher coefficients of friction or U. Southbend has not gone the way of the drum brake theory ;D
Don~
I am getting the idea that this does not apply to my manual transmission.
[/quote]
It does Scotty. Your Southbend clutch is using a material with a higher "U" and the clamp load is increased not by a stiffer spring, but applying more pressure from having the pressure ring machined to apply the most clamping force it can on its bell curve. The same thing is done by some tq convertor/transmission builders, increasing clamp load by bumping line pressure and using a friction material with higher coefficients of friction or U. Southbend has not gone the way of the drum brake theory ;D
Don~
11-19-2002 | 05:53 PM
#29
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Re:New Torque Converter Design
[quote author=GONZO link=board=7;threadid=7241;start=15#69534 date=1037745497]<br>[quote author=StakeMan link=board=7;threadid=7241;start=15#69508 date=1037742580]<br>This is a great debate.<br>[/quote]<br><br>I sure could go for a cup of Folgers! 
<br><br><br>[/quote]<br><br> :
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