I have a reprint of a 1902 Henry Diston & Sons catalog. From the last page: The average thickness of single belts is 3/16 inch and a safe working load is assumed to be 45 lbs/inch of width. A velocity of 60sq ft/min = 1hp. Belt motion should not exceed 3,000ft/min. Where narrow belts are run over small pulleys, a distance of 15ft between shafts, and which gives a sag of 1 1/2 to 2 inches in the belt is good practice. For main belts working on large pulleys, a greater distance and sag is desirable. The strongest side of the belt is the flesh side 1/3 the way through, therefore run the hair side on the pulley. A common rule for determining the width of a single belt 3/16 inch thick to transmit any number of horsepower, is to multiply the actual hp by 1,000 and divide by the velocity of the belt in ft/min, which gives the belt width in inches. A one inch belt @ 800 ft/min = one hp. To find the length of a belt, add the dia. of the two pulleys togather, divide the result by two and multiply the quotient by 3 1/7, then add the product of twice the distance between the center of shafts and you have the length required. (I assume this length will provide the reqisite sag.) The resistance to a belt slipping is independent of its width. A belt's necessary width is determined by the strain on it. Long belts are more effective than short ones. A strain of 350 lbs/sq inch of section is a safe working load. The pulley should be a little wider than the belt.
That is all it says and I don't know where else to look. I've got a SA and I look at the pulley and realize without an old-timer around, I'm adrift. I've never found anyone with first hand knowledge on how to use big belts to run large machines safely. I'm trying to reconcile the 45 lbs/inch of width mentioned first with the safe working load of 350 lbs/sq of section mentioned last. I believe they are talking about area in the first and thickness in the second. The article presupposes you know what "narrow" belts, "small" pulleys, "large" pulleys and a "greater distance" are. Hair side on the pulley is corroborated in another source. Take the advice on static dissipation seriously. Static will build on the driver and driven machines as well as on the belt itself.
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