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Automotive Timing Belt

by robs314
Tags: automotive, design, timing belt
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Apr9-11, 10:26 AM
P: 16
I am choosing a timing belt for a 60kw continuous system at roughly 1100rpm. This is a relatively low speed application.
After using the belt selection programs written by Gates, Emerson and Goodyear, they all seem to point towards quite hefty installations with large pulley diameters and widths.

However, automotive belts must be able to transfer powers of this sort of magnitude, yet the pulleys used in these applications are much smaller.

I have found it very hard to find engineering manuals/specs for automotive belts. It seems only possible to search by car model type.

Does anyone know of any sources of automotive belt specs and manuals for the purpose of design?

Many thanks
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Apr9-11, 12:49 PM
P: 2,529
I seriously doubt it takes 60 kw to turn over a camshaft. So I would say it's not apples to apples.
Apr9-11, 01:44 PM
P: 16
My application is not an automotive one. The motor that needs a belt really does develop 60Kw, which I accept is quite large.

Apr9-11, 05:00 PM
Sci Advisor
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P: 7,162
Automotive Timing Belt

Apart from the mismatch of power requirements, many production automobile belts are wimpy designs that are "throw away" replacement items. (On the last GM car I owned, the original 80,000m design life had been reduced to 40,000m, by which time not only was the belt just about shredded but the cheap plastic tensioning pulley was usually cracked as well. (Silly me for buying an American-designed engine, I guess).

40,000 miles is only about 1000 hours life. That's not much if you need something that runs continuously..

Also, power = force x velocity, so if you want high power at low RPM that will mean a bigger belt to take the bigger force, or large pulleys to increase the belt speed.
Apr9-11, 05:21 PM
P: 16
Many thanks for your replies

I had a suspicion that it was down to longetivity more than anything else. However, my application only needs to be operational for less time than a car's engine, so would it be wiser for me to go down the automotive route?
If it were a blower, or compressor or something running all day, I wouldn't hesitate with a larger spec.

Apr10-11, 01:45 AM
P: 563
You're asking the belt to withstand almost 400 ft.lbs of torque. If you have a 4 inch pulley, that's almost 1200 lb of force acting to pull the belt apart. That's pretty serious.

How big a belt would you need to lift the front end of the average small car? The typical timing belt might survive but the teeth wouldn't.

Call the tech line at Gates and listen to the tech adviser.
Apr10-11, 04:12 AM
P: 16
It has put my mind at rest that I was following the right approach to start with. I just thought automotive belts should be worth looking at, that's all.

Your advice has meant that I will not have to spend any more time looking for automotive belting data.

I'm very grateful, thank you :)

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