# Motor pulley size



## derf (Apr 17, 2018)

When I got this 9A, it obviously had the motor changed out and just a single pulley on it. The pulley measures 2-1/2". This model has the 4 step V pulley system on the spindle, and the 2 large pulleys on the counter shaft measure 9.940", and 9.125". My question is: what should the pulley diameters be on the drive motor?
 I've seen several on e-bay, but the sizes vary.


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## Ulma Doctor (Apr 17, 2018)

I can measure the pulley on my Hercus lathe and post the dimensions when i get home. 
They should be identical or very close to Souh Bend specs


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## Ulma Doctor (Apr 18, 2018)

My drive pulley is a single groove sheave, 3" in diameter on the motor
my driven pulley is a single groove sheave,  9-1/2" diameter on the countershaft

i hope the information is helpful


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## derf (Apr 18, 2018)

Actually that doesn't help much at all, but perhaps you misunderstood the question so I will define it a bit more.
 The original set up uses 2 flat pulleys (9.125" and 9.940") on the countershaft, and 2 V pulleys on the motor shaft (size unknown at this time) to create a high and low primary speed to the cone pulleys. The diameter of the sheaves on the motor pulley correspond to the diameters on the flat pulleys so the same belt length works on both.
 Something a lot of guys are confused about, is why are there flat pulleys on the counter shaft and V pulleys on the motor? It's very simple. By using flat pulleys on the countershaft, One can roll the belt off and change to the other set of pulleys without adjusting or moving the motor. Something that cannot be done easily using 2 V pulleys.

So, with that explanation, what I'm looking for is the diameter of the sheaves on the motor pulley that correspond with the sizes of the flat pulleys. There is no doubt a factory standard that was used on this model. I know over the years these old machines have been re-motored, rebuilt and revamped to the point some do not have the original pulleys, but it would be nice to know exactly what they came with.


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## LucknowKen (May 11, 2018)

*My 9A drive pulleys are dual groove sheave.
1 .125" and  2.375"*


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## Technical Ted (May 11, 2018)

See if any of this info will help.

Ted


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## derf (May 12, 2018)

That's what I was looking for. It's a little hard to read but, according to the chart it takes a 2-3/32" and 3-13/32". Those are South Bend engineered sizes, not something that is found on the shelf. But I did find a combination that works. I started with a 3" on the high speed side and used a 1-3/4" on the low speed, and tweaked the diameter by cutting the groove wider until the belt diameters mated up. Now you can roll the belt off one set and right back on the other with no hassle.


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