Are polychain belts and sprockets commonly available the way V belts pulleys, weld on hubs and belts are. What about cost, would 2 sprockets and a belt be $100, $1000...ballpark? You guys are great, I posted this same question in a airboat forum and not one response.
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I don't know if I would use the word commonly, but they are available, and a good bit more expensive.
Will you be doing your own machining?
I will do the welding and a friend is a machinist who will make the parts I need.
Have you checked the horsepower transfer rating of a B belt, in continuous service? I think it's only a few hp.
Pete Stanaitis
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mark wrote:
I got the idea of using double V belts from using the same setup on a firewood saw bench I built, It mounts on the 3 point hitch of my 70hp tractor and turns a 36" blade. It works great on that and I assume the saw would have much more load on the belts. The saw typically runs for
6-8 hours at a time.
I seriously dowbt that saw absorbs 70 hp!
Take a look here...
If you go with multiple vee belts in parallel, you have to use factory machined pulleys and matched belts. And with 100 HP you could have to go with four belts in parallel.
You need 'matched' belts to spread the load, but they don't sell them as "matched sets" anymore because it complicates the warehousing and such - Plus, fools work at parts warehouses. Fool #1 splits the set because they are out of singles, then Fool #2 fills the Matched Set in again with a single that is not matched...
Now they pick out three or four belts and check the production codes to make sure they are from the same date and production batch, and they should be more than close enough in length to work together. And you should double check the codes before installing them to make sure they did it right.
Or look into the cogged blower belts. They handle a lot more HP.
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Snowmobile drive belts handle 200hp easily and usually have 3:1 gear reduction in low range. They typically run 12" center-to-center distance between the shafts. They run smooth sheaves even though the picture makes it look like they are toothed belts... they are v-belts that grip on the sides rather than on the flats. This is the longest one I found:
But turning a prop they will only last about hald al long as a snowmobile braking trail in deap snow - which is generally less than
30 hours. Braking trail (using all the power) is REALLY hard on belts. Props are worse.
Use Harley final drive pulleys . Toothed belt , good for up to about 130 HP and you can get real close to the ratio you want with off-the-shelf parts . And probably get the pulleys used from ebay for a reasonable price . Might have to source and modify a Harley main drive gear to mount the drive pulley on .
I dunno....
Assuming a 33 inch diameter tire that works out to 611 RPM at the rear tire.
Youd probably want prop RPM 3 to 4 times that in order to use an off the shelf propeller. 1800 - 2400 rpm.
Which would mean a larger front pulley, or a smaller rear.
Are there off the shelf parts that can make the ratio work?
The prop hub will be about about 2 feet above the engine as I would like to keep the center of gravity low. I can't picture what you are suggesting with the timing chain? Could you explain more. Thanks
Maybe the shaft drive from a motorcycle. The 1000+ cc bikes.
Heat is what kills snowmobile belts... breaking trail at low speeds doesn't provide enough airflow through the hood to cool the belt. He'll have plenty of airflow over the belt to keep it cool.
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