# Chain vs Belt



## JRP3 (Mar 7, 2008)

I love my belt!  I'd choose one over chain any time I could from now on. Quieter, no lube spraying around, no stretching and adjusting.


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## tropes (Jul 24, 2011)

JRP3 said:


> I love my belt!  I'd choose one over chain any time I could from now on. Quieter, no lube spraying around, no stretching and adjusting.


Quiet is good but what about strength; the torque of the K91 4003, 72Volt with 1:1 ratio from drive (motor) to driven (jackshaft) is my concern.


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## Rational (Nov 26, 2011)

Here are some formulas. 
http://en.wikipedia.org/wiki/Belt_(mechanical)
The link worked the first time I accessed it. If not try. . .
http://www.google.com/search?client=safari&rls=en&q="belt+drive"+wiki&ie=UTF-8&oe=UTF-8
Computers are great when they actually work. 

BTW, chains require lubing, belts don't.


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## JRP3 (Mar 7, 2008)

They do run belt drives on supercharged blowers and on timing belts. The proper sized belt should be fine. Gates Belts has a belt calculator if I remember correctly.


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## JRP3 (Mar 7, 2008)

http://www.gates.com/Europe/designflex/index.cfm?location_id=3433


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## tropes (Jul 24, 2011)

Rational said:


> Here are some formulas.
> http://en.wikipedia.org/wiki/Belt_(mechanical)
> The link worked the first time I accessed it. If not try. . .
> http://www.google.com/search?client=safari&rls=en&q="belt+drive"+wiki&ie=UTF-8&oe=UTF-8
> ...


I'm not sure if I can upload a pdf file but I did get a recommendation from the technicians at Gates before i purchased. In part it reads:

Drive Information 
Known Belt: Poly Chain Carbon - 8MGT-640 - 21.00 mm 
Speed Ratio: 1.00 
Input Load: 50 lb-ft 
Service Factor: 1.5 
Design Power: 75 lb-ft 
Center Distance: 7.56 in 
DriveR DriveN 
Known Size: 32 Teeth 32 Teeth 
RPM: 2000.0 2000.0 
Maximum Rim Speed: 6500 ft/min 6500 ft/min 
Shaft Diameter: 0.875 in 0.75 in 
Bushings Checked: QD 
Belts Checked: Poly Chain Carbon 
Electric Motor 
SELECTED DRIVE 
Belt Type: Poly Chain Carbon - 8M 
Speed Ratio: 1.0 
dN RPM: 2000.0 
Rated Load: 68.77 lb-ft, ODR: 0.92 
Belt Pull: 481 lb 
Center Distance: 7.56 in 
Install/Take-Up Range: 6.18 in to 7.59 in 
Noise: 75 dB @ 1067 Hz 
Savings: The three year savings can be up to 1652 KW - $495.60 
Belt DriveR DriveN 
Part No: 8MGT-640-21 PB8MX-32S-21 PB8MX-32S-21 
Product No: 9274-1080 7715-2032 7715-2032


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## Rational (Nov 26, 2011)

Lacking a glossary, if you know the pulley radius R in feet and the belt pull of 481 lbs I'd think you can figure max torque, =Rx481. Then knowing the max RPM you know the power, hp=T*rpm/5252. But, for long belt life I'd hope an ME chimes in on this.

http://www.engineeringtoolbox.com/belt-transmission-power-efficciency-d_1378.html

http://www.engineeringtoolbox.com/length-belt-fans-motors-d_872.html


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## Woodsmith (Jun 5, 2008)

I'd like to have a belt but the machining to fit one is prohibative at the moment.
I will run a duplex chain and then think about a belt when the conversion is road proven.


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## tropes (Jul 24, 2011)

Woodsmith said:


> I'd like to have a belt but the machining to fit one is prohibative at the moment.
> I will run a duplex chain and then think about a belt when the conversion is road proven.


In my case the machining is not a factor but the cost of Gates sprockets is high. Fortunately, one of our sponsors is a NAPA dealer, Wayne Myron at Ogema Farm & Auto. http://www.napaautopro.com/car-garage/SK/ogema/NT0005180-po-box-249-ogema.html


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## JRP3 (Mar 7, 2008)

I was able to get cheap sprockets through http://www.grainger.com


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## tropes (Jul 24, 2011)

JRP3 said:


> I was able to get cheap sprockets through http://www.grainger.com


The Gates sprockets are part# PB8MX-32S-21.
I couldn't find them at Grainger.


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## major (Apr 4, 2008)

Hi tropes,

Two things you might find troublesome. One is the belt hopping on the cog teeth. And the other is difficulty in changing ratios.

I like the idea of cogged belts and used it on an EV. Had to go to elaborate outboard support bearings to prevent the belt from jumping the cog teeth. Then it was a nightmare to change the belt, which never did run true and would wear the edges badly. Even if you can get it to work without outboard supports, the number of cogs and belts needed for a range of ratios will be more than with chains and sprockets.

I'd love to try it on our race bike, but the swing arm passes thru it  Ripperton started out with a belt on his bike, but soon gave it up due to hopping teeth. 

On last year's bike, we used a belt primary reduction off the motor shaft and then a secondary chain to the wheel. It was about 3 inch wide and had both cogs supported both sides. It did hold up....and that was 100+ hp up to 12 kRPM. We did our ratio changes with the chain.

major


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## JRP3 (Mar 7, 2008)

I remember Rip's problems with belt jumping, he had a longer belt and more power than I do, I'm sure you had the same. Of course Harley's seem to do OK with them. Looks as if Grainger no longer carries the Gates stuff, I guess I just got lucky. Those things are expensive at regular prices.


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## major (Apr 4, 2008)

JRP3 said:


> Of course Harley's seem to do OK with them.


Maybe they know what they're doin'


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## tropes (Jul 24, 2011)

major said:


> Hi tropes,
> 
> Two things you might find troublesome. One is the belt hopping on the cog teeth. And the other is difficulty in changing ratios.
> 
> ...


I have faith that the machinists at Pro Metal http://www.prometal.ca/ have the skill to overcome any belt hopping and ratio changing problems.


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## Woodsmith (Jun 5, 2008)

major said:


> Maybe they know what they're doin'


My Harley was belt drive.
Replacement belts and sprockets, in the UK at least, were not cheap.

I spoke with a UK chap who had a belt drive from two Agni motors to the transmission on his Ford Fiesta. He had the problem with the belt jumping teeth and had to use a car jack to apply sufficient tension to make the belt work.
That sorted out the jumping but increased the friction.

The other method I think is to have larger sprockets but that gets difficult with a motorbike type assembly.


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## tropes (Jul 24, 2011)

major said:


> Maybe they know what they're doin'











This is how I plan to set up the belt drive. My concern is the strength of the belt vs chain not the belt hopping.


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## JRP3 (Mar 7, 2008)

That doesn't mean you'll be immune to the belt hopping problems that others have had. Harley's do use a much wider belt. Another trick may be to have an idler pressing on the belt near the smaller pulley, assuming that's where the problem might arise. I think you an also use belts and sprockets with a deeper tooth profile.
I guess this worked for this setup










http://www.evalbum.com/1396


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## tropes (Jul 24, 2011)

JRP3 said:


> http://www.evalbum.com/1396


The belt in this photo is very unique. Notice no flange on the sprockets. It's made by Goodyear and has herringbone teeth. Great engineering.
To avoid belt hopping the two pulley shafts must be exactly parallel and held in place (hence the plate between the two pulleys). The shaft material must be of sufficient strength to avoid flexing. My drag racing background tells me a belt is the way to go but it seems Junior dragsters have not found success with them hence my apprehension.


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## Rational (Nov 26, 2011)

tropes said:


> My concern is the strength of the belt vs chain not the belt hopping.


They may both be related through the modulus of elasticity of the belt material.

I'd use the small pulley radius to figure the pull on the belt due to torque. If it's 0.125' then to get 481 lbs belt tension you'd need 60 lb-ft.


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## tropes (Jul 24, 2011)

Rational said:


> They may both be related through the modulus of elasticity of the belt material.


I chose this Gates belt, in part, for that reason. It is made of carbon fiber reinforced plastic and the tensile modulus of the belt is enhanced by applying the force with respect to the carbon fiber molecular structure. The Young's modulus of carbon fibre in this case would be about 26,000,000 as compared to steel at 29,000,000.


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## Rational (Nov 26, 2011)

If you are near a technical/college bookstore, the Schaum's Outline Series has solved problems of many types, and the transmission of power using belts is probably one of them. In my old copy of The Machinery Handbook this task takes up several pages.

A slightly harder book for this use is
http://www.amazon.com/Mechanical-Sample-Examination-Michael-Lindeburg/dp/159126006X
My local library happened to have a circulating copy of this book. You may be able to get it through inter-library loan.

With the time and money invested in these projects I'd be doing at least some calculations first.


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## tropes (Jul 24, 2011)

Rational said:


> If you are near a technical/college bookstore, the Schaum's Outline Series has solved problems of many types, and the transmission of power using belts is probably one of them. In my old copy of The Machinery Handbook this task takes up several pages.
> 
> A slightly harder book for this use is
> http://www.amazon.com/Mechanical-Sample-Examination-Michael-Lindeburg/dp/159126006X
> ...


Good suggestion. Thank you. I have been scouring the internet for as much info as possible. The Gates engineers and technicians have also provided sources. Because there are so few electric junior dragsters it is difficult to accure specific first-hand data.
tropes


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## Rational (Nov 26, 2011)

Correction
http://www.amazon.com/Mechanical-Engineering-Reference-Manual-Exam/dp/1591260493/ref=pd_sim_b_2


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## tropes (Jul 24, 2011)

Rational said:


> Correction
> http://www.amazon.com/Mechanical-Engineering-Reference-Manual-Exam/dp/1591260493/ref=pd_sim_b_2


That's better; I really didn't feel like taking an exam!


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## Rational (Nov 26, 2011)

tropes said:


> That's better; I really didn't feel like taking an exam!




If you Google exact quotes from this book you can find chunks of it on the Web. Then we can all follow along. Four or five consecutive words are usually enough to uniquely specify this book.


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## SWF (Nov 23, 2007)

You can purchase Gates sprockets and belts at McMaster-Carr. I got two 40 tooth (4") 21mm GT2 sprockets and a 800mm GT carbon belt for about $300 including the required bushings. Needed a 1:1 drive for my setup and this seemed to fit the bill. Rated power handling capability with these size sprockets and GT2 belt is [email protected], [email protected], and [email protected] You can get HP ratings for other size sprockets and also power rating correction factors for different applications using their drive-design guide at their website.


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## tropes (Jul 24, 2011)

SWF said:


> You can purchase Gates sprockets and belts at McMaster-Carr. I got two 40 tooth (4") 21mm GT2 sprockets and a 800mm GT carbon belt for about $300 including the required bushings. Needed a 1:1 drive for my setup and this seemed to fit the bill. Rated power handling capability with these size sprockets and GT2 belt is [email protected], [email protected], and [email protected] You can get HP ratings for other size sprockets and also power rating correction factors for different applications using their drive-design guide at their website.


I decided to go with a Gates PolyChain belt which I purchased from the local NAPA store. I ordered 2 sprockets from Pfeifer Industries; 25 tooth driver and 115 tooth driven. Ratio is 4.6:1. It's just a guess but I will have to start somewhere. Sprockets make good Xmas presents!
BTW, what is your setup?


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## SWF (Nov 23, 2007)

tropes said:


> I decided to go with a Gates PolyChain belt which I purchased from the local NAPA store. I ordered 2 sprockets from Pfeifer Industries; 25 tooth driver and 115 tooth driven. Ratio is 4.6:1. It's just a guess but I will have to start somewhere. Sprockets make good Xmas presents!
> BTW, what is your setup?


In the middle of an ATV conversion (Polaris Sportsman 500) which I hope to have running by mid January. AC-20 motor and 32 CALB 100Ahr cells. The engine originally drove the transmission with a variable speed belt system like on a snowmobile, so it was relatively straight-forward to connect the AC-20 to the input shaft on the transmission using the gates sprockets and belt. Keeping the two-speed hi/low transmission made sense based on the work I plan to do with the machine, and also kept the on-demand all-wheel drive function of the original machine intact.


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## tropes (Jul 24, 2011)

SWF said:


> In the middle of an ATV conversion (Polaris Sportsman 500) which I hope to have running by mid January. AC-20 motor and 32 CALB 100Ahr cells. The engine originally drove the transmission with a variable speed belt system like on a snowmobile, so it was relatively straight-forward to connect the AC-20 to the input shaft on the transmission using the gates sprockets and belt. Keeping the two-speed hi/low transmission made sense based on the work I plan to do with the machine, and also kept the on-demand all-wheel drive function of the original machine intact.


Crazy Mountain Motorsports is now using a belt drive system similar to the one I will be using http://www.crazymtn.com/sifiso/pages/cmxds.html
They claim it is stronger than the chain drive. I will not be using a tension pulley since the C-C distance between shafts is less than 14 inches.


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