Well, I'm ready to purchase the pulleys for the 1 1/2" EMD Model 40 Switcher.. I'll be using two 350 watt 24V motors, connected to a common "center" shaft, with a 2 to 1 belt reduction to a jackshaft. Then another 2 to 1 reduction to each axle.. I've been looking at using 3/4" timing belts, type "L" But am wondering if they might be "overkill" Would 1/2" belts be strong enough? As this is my first attempt at anything bigger than 3/4" scale, I was just wondering if I might be trying to over build this thing.....
Thanks; John
Timing Belt Question.....
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amadlinger
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Re: Timing Belt Question.....
Hi John,
What an amazing coincidence: I just bought the pulleys for my 1.5" scale GP9 project last week and wrestled with the exact same question! My locomotive will be set up just like yours, with one central electric motor and pulleys/driveshafts going down to the trucks. I Googled "timing belt torque rating" and found this website as the first link:
http://www.roymech.co.uk/Useful_Tables/ ... belts.html
About half way down the page I found the attached chart, which answered my question exactly. If you read the text a bit, you'll see that this chart corresponds to 1" wide L-belts and 1.5" wide H-belts. Scroll down to the "Table of Belt Width Factors" farther down on the page to determine how to de-rate the numbers in the chart for 1/2"/12.7mm wide (multiply the rating by 0.45) and 3/4"/19.05mm wide (multiply the rating by 0.72).
In my case, I'm using an Etek-R motor rated for about 3500 watts at 48V & 3600rpm, which is near the top end of the 1" wide L. You'll have to check it out for your situation.
Hope this helps!
Sincerely,
Adam
What an amazing coincidence: I just bought the pulleys for my 1.5" scale GP9 project last week and wrestled with the exact same question! My locomotive will be set up just like yours, with one central electric motor and pulleys/driveshafts going down to the trucks. I Googled "timing belt torque rating" and found this website as the first link:
http://www.roymech.co.uk/Useful_Tables/ ... belts.html
About half way down the page I found the attached chart, which answered my question exactly. If you read the text a bit, you'll see that this chart corresponds to 1" wide L-belts and 1.5" wide H-belts. Scroll down to the "Table of Belt Width Factors" farther down on the page to determine how to de-rate the numbers in the chart for 1/2"/12.7mm wide (multiply the rating by 0.45) and 3/4"/19.05mm wide (multiply the rating by 0.72).
In my case, I'm using an Etek-R motor rated for about 3500 watts at 48V & 3600rpm, which is near the top end of the 1" wide L. You'll have to check it out for your situation.
Hope this helps!
Sincerely,
Adam
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Bill Shields
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Re: Timing Belt Question.....
John:
One thing that you have to ask is 'how many teeth engaged' between the belt and the pulley.
This has as much bearing on the question (sometimes more so) than belt width.
One thing that you have to ask is 'how many teeth engaged' between the belt and the pulley.
This has as much bearing on the question (sometimes more so) than belt width.
Too many things going on to bother listing them.
Re: Timing Belt Question.....
John
I spent some time in industry working on productions machines with lots of timing belts. We were having some problems on a new custom made machine with the timing belts jumping teeth. We had a Gates rep in to help out with the problem. He pointed out a couple of problems; one was that we were using to wide and heavy of a belt. With the belt to over rated for the job we were not able to get enough strech on the belt to seat it into the pulley. So going oversize is not good. The second was that we had to match the pulleys and the belt. Different belts have slight different shaped teeth on them and require a mating pulley. So don't buy some surplus pulley and slap a toothed belt on it. All the specs for width and pitch may read the same but the profile of the tooth and mating pulley can vary quite a bit. There is a fair amount of information on this from Woods and Gates.
lg
no neat sig line
I spent some time in industry working on productions machines with lots of timing belts. We were having some problems on a new custom made machine with the timing belts jumping teeth. We had a Gates rep in to help out with the problem. He pointed out a couple of problems; one was that we were using to wide and heavy of a belt. With the belt to over rated for the job we were not able to get enough strech on the belt to seat it into the pulley. So going oversize is not good. The second was that we had to match the pulleys and the belt. Different belts have slight different shaped teeth on them and require a mating pulley. So don't buy some surplus pulley and slap a toothed belt on it. All the specs for width and pitch may read the same but the profile of the tooth and mating pulley can vary quite a bit. There is a fair amount of information on this from Woods and Gates.
lg
no neat sig line
I am unique, just like everyone else.
Re: Timing Belt Question.....
I worked on a project using timing belts for an airplane drive, talked to Gates many a times(never mentioned it was for an airplane). They have a very nice piece of software for designing belt drives, it will tell you everything that you are doing wrong, and gives suggestions to which belts to use and even makes sure your application is designed right to use standard sized belts.
Design IQ is the name of this free application
http://www.gates.com/designiq/index.cfm ... n_id=11292
Design IQ is the name of this free application
http://www.gates.com/designiq/index.cfm ... n_id=11292