v belt sizes

The other day I received a letter from my cousin telling me of his experiences
replacing a drivebelt on a rooftop air conditioner on his church. The old belt
was marked A-40 so to be on the safe side he bought a A-40-1/2. It was way too
tight so he got an A-41. Still too tight so he had to move the motor.
I remember having similar belt problems years ago but I'm wondering why belt
manufacturers havn't been able to standardize their length measuring system?
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Probably it stretched. A *lot*. Although that begs the question of how it got there in the first place, unless the motor was adjusted as it wore.
I should know, our drill press needs a new belt, I now have the motor in the fully extended position all the time.
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @
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Reply to
Tim Williams
I change belts almost every day in my job. Belt lengths are standardized. If the old belt was an A-40 the new one should be an A-40. The old belt probably was stretched. Greg
Reply to
Greg O
Chuckle..I just completed a Hardinge HC/OmniTurn retrofit..and did a direct drive conversion as well by pulling the varidrive, installing double sheave pulleys etc etc.
I ordered a matching pair of B-88 belts from Graingers..and one was at least 1" longer than the other. Checking their stock..they tended to run from 3/8 to 1.5" out of spec.
I ordered a matching pair of Browing belts (which is what I should have done in the first place but was in a hurry) from my usual source and they WILL be matching.
That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell
Reply to
Hey Engineman,
Went through something similar for the lawn tractor just the other day. The local Husqevarna (SP??) dealer carries Dayco brand belts. An AP92 is 94 inches long and a AP67 is 69 inches. Just add two inches to what the "number" is. I asked why, and he says it is because Dayco measures a belt by the inside or contact circumference, while some other manufacturers use the outside circumference.
So, a quick go-round with my calculator says that if the belt "thickness' (depth) is 3/8", then a belt with ID circumference of 92 inches will have diameter of 29.29". Add 3/8" thick for the belt to get OD diameter of 30.04" and an OD circumference of 94.35.
Take care.
Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXX
Reply to
Brian Lawson

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