Need belt size help

[37 chief]

I'm installing a three groove pulley on my flail mower. It had a two groove but with all the thick weeds It is slipping. I removed the two three groove pulleys from my old mower, and installed on the one I am using. You would think the belt distance would be the same, with the same brand mower, but no. I have the two shafts center to center is 17 inches. The two pulleys are both 7 1/8 across. With that information how much should be allowed to install the belts. The old belt is a B 58. The new one should be a B something. Thanks for any help. Stan

 

[Janicholson]

It depends on how deep the belts run in the pulleys. I eould take one of the old belts, cut it in one place, wrap it on the new pulleys so that the gap is measurable. If the adjustment is as close as it gets, and add maybe an inch for new, and adjustability. Jim

 

[JimKS]

If the pulleys on both mowers are the same size measure the shaft centers on both mowers.Then add or subtract double the distance depending if the new set up is longer or shorter to the existing belt.

Jim

 

[teddy52food]

I get 56.4 but that is at the top of the 7 &1/8 pulleys.

 

[Steve@Advance]

I come up with a B54 which is 57".

You probably already know, the belts need to be "matched set", meaning they need to have been made within the same batch to get the matched length.

 

[bradley martin]

I have been told by several different suppliers that matched sets are no longer available. They claim that modern manufacturing is precise enough that matched sets are a thing of the past. Whether that is true I don't know, but when distributors for Gates or Goodyear tell me they cannot order matched sets I have to take their word for it. That said, I have not encountered a problem with mismatched lengths.

 

[Steve@Advance]

Bradley, that's true to a certain extent.

As long as they are the same brand and roughly the same age they should be pretty close.

Where the problem come is mixing something new with one that's been hanging on the wall for 10 years, or mixing brands.

Even have to watch what's really in the sleeve, sometimes business change suppliers, they will resleeve existing stock so everything matches the computer stocking numbers.

 

[moresmoke]

You can get a banded belt, then you are sure it is a matched set.

 

[BarnyardEngineering]

If the distance between the shafts did not change, and the diameters of the belt pulleys did not change, then the belt length should not have changed. So, color me confused here.

 

[Mark-Mi]

Same thing I have been told by a couple of lower level suppliers. Have not encounter a belt length unequal problem on several installations.

 

[37 chief]

Probably the two mowers had a design change for some reason, and the two shafts were not the same distance apart. Stan