'Rules of thumb' when using flat belts

I've limited experience using flat belts, but I've an application were I will be using one. Wondering what 'rules of thumb' might exist, ie, distance between pulleys, belt size for Hp rating, etc.

Thanks,

Mark
 
What are you planning to run. I have a hammer mill and corn sheller that uses a flat belt. I position the tractor so the belt has to be crossed - it doesn't wobble all over the place like that. The implement
will have to be fastened down by some means so it can't move. Some flat belts are designed to run a certain direction and if so will say so on the belt. Other than that just line up the tractor to the
implement so the belt is running in the middle of the pulleys and run it tight but not so much it starts bending shafts. Belt length doesn't matter.
 
Put the belt on the implement pulley first and lay it out on the ground where the tractor will sit. That makes it easier to position the tractor.
 
Belt length does mater. Too long and with smaller implements or tractors you cannot pull it up tight. And a 40' belt you can only have about 18' between implement pully and power pully, that 40 foot is total lengthn not a working length that is 1/2 total length minus what it takes to go arounf half of each pullys. And don't put a belt with a lacing on a small pully like a hammer mill as the curvature of the pully will tear the lacings out. For width you need to measure the driven pully and use that even if it is only half the width of drive pully. For something like a stand alone cord wood saw about 15' to tractor is a good length as totry to use a 40' bekt you could not fasten that saw down enought to tighten a 40' or longer belt. Now a theshing machine with its extra weight will need possibly a60 to 80 foot belt and will need a belt as wide as tractor pully. And having the tractor missaligned as much as 1/8" can throw a belt off. You just may have to move front end of tractor that small a distance without moving back end. And all belts wrom power source to implement are supposed to have the twist in them to keep them from flopping around to bad. on some setups you might need 2 or 3 twists. But on melts mounted on apiece of machinery they do not run a twist as the pullys are not far enough away from each other for that. What type of machinery and what tractor do you plan on using? That cam help us recomend an aproperate belt. And a canvas belt requires a bigger pully than a rubber belt does. If it takes you an hour to get it alinged with no experience you are doing good.
 
I have a 1902 reprint of a Henry Disston Co. catalog. It contains a page devoted to rules-of-thumb for belting. At this time, Distton's saws and drills are made for hand tools but in the past Disston made a huge variety of saws, hand tools and machines for logging and saw mills; all at a time when power was distributed by belting.

Average singe-belt thickness - 3/16 inch.
Safe working load - 45 lbs./inch of width.
60 square feet/min. = 1 hp.
Maximum narrow belt speed over narrow pulleys - 3,000 ft/min. with 15 feet between shafts and 1 1/2 to 2 inches of sag.
Main belts and large pulleys require more distance and sag.
For greatest strength, run the hair-side of the belt on the pulley.
To determine the width of a single belt - Multiply hp. by 1,000 and divide by belt velocity in ft./min. The answer is belt width in inches.
A one inch belt at 800 ft./min. = 1 hp.
To find the length of a belt - Add the dia. of both pulleys, divide this by 2, multiply that answer by 3 1/7, to this add the product of two times the distance distance between shaft centers = belt length.
Belt slippage is independent of belt width. If a belt slips, there is too much strain on it.
Long belts are more effective than short ones.
A strain of 350 lbs./sq. in. is a safe working load.
The pulley should be a little wider that the belt.

Unfortunately, for us, just what a "narrow" belt is, or what "small" and "large" pulleys look like and what length constitutes a "long" belt - none of this is defined. Contemporarily, they didn't need to be.
 
From tractor to threshing machine there is another reason for the twisted belt. The direction of rotation of pulleys must be known and belted accordingly.
 
"But on melts mounted on apiece of machinery they do not run a twist as the pullys are not far enough away from each other for that."

I disagree. Several flat belts ON threshing machines have a twist = again it relates to KNOWING your direction of pulley rotation and belting accordingly.
 
make sure there is a ground in place on both the driven machine and the driving machine. A chain over the axle and touching the ground is sufficient. Static electricity can build up to significant levels if not shunted to ground somehow.
 
I have not been around that many trashing machines to see that. I know on corn shreaders there were no twusted belts.
 

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