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Help with overhead drive

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Setting up a dupont 50lb hammer. All dismantled cleaned, Lubed and reassembled
I had ordered a 2.5" flat belt of synthetic material from mcmaster Carr. I also ordered a paper pulley to drive the system. The hammer specs called for 375 hits per minute. The motor is a 3 hp and drives at a rpm of 1160. I did my calculations and ordered the pulley at 3.5" for direct drive. Now the hammer works, but far from optimally. There seems to be a good deal of slippage on the 3.5" drive pulley which is understandable mechanically but dissapointing from a performance standpoint. Does anyone have experience with a direct drive motor to hammer setup with these kinds of ratios or is some type of overhead reduction jackshaft necessary. I would rather direct drive due to a premium on space.


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Best practice for slip belt set ups is to have a jack shaft, but if that is out of the question then you can try and get by with a small pulley on the motor. Make your belt as long as you can (motor farther from the hammer) so the belt wraps more of the pulley. Also, be sure the motor rotation and idler pulley are set up to be complimentary, there is another thread here in the power hammer section about how to do that.

Pulling on the end of your motor shaft will probably shorten the life of the motor, YMMV.

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Have you tried belt dressing? The newer synthetic belts have a different friction (whatever) than leather belts so it may need a little belt sauce. Even a little bar soap helps, just touch the inside of the belt with a bar of Ivory while it's turning. I don't know if dressing the belt will help but it can't hurt. Belt dressing is also available at the auto parts store in spray cans.

Pics, we love pics.

Frosty the Lucky.

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A bigger pulley will help with a jack shaft, you might not have ideal friction but on a 50# it shouldnt be too bad

Getting the hammer linkages tuned just right and running the way you want them is the key every hammer is a little different.

At least with a dupont you dont have a little giant clutch a slack belt is pretty simple, if you cant get good control you may find that a jackshaft is what you need.

With mine i put a 10 1/2 inch pulley on the motor which was pretty expensive and a 20 inch pulley to that with a 10 inch drive pulley for the 3 1/2 inch wide belt.

The rotating mass is close to 200 lbs the motor never slows down because it engages with so much inertia

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