Need advice on stump grinder belts.

[defensiblespace]

View attachment 238563View attachment 238564
I just bought a used Vermeer SC252 stump grinder. The first thing I did was change the belts. After my first half hour of grinding, I noticed that the belt to the cutter wheel was smoking. I took the shield of the next day to find some of the kevlar threads poking out of the sides of the belt. It seems like the specs called for that belt to be super tight, which I did. I did not hear it squealing at all. The first stumps I did were a bit punky and I was taking about half an inch at a time, so I don't think I was going to hard on the machine. It has a greenteeth setup which is in pretty good shape. The jackshaft appears to be aligned straight as an arrow, so I don't think that is the problem either. Also, what do you guys use to measure belt tension on the v-blets? I think it called for 3/8" deflection at 9lbs, so I dropped a 9 pound weight on one of the belts and measured the sag in the belt. Am I on the right track here?

 

[2treeornot2tree]

I would check your pulleys and make sure you dont have a bur or a bend inside the track of the pulley that is rubbing the belt. If everything looks good there, I would check to make sure one of the bolts that holds the cover on isnt to long and is rubbing the belt. Looks like you have a bur or bent pulley though.

 

[imagineero]

3/8" deflection at 9lbs really isnt super tight. If you want to get technical, you can measure it with a fish scale. Overtightening belts is far more common than undertightening. Basically you want the belt only just tight enough to stop the squeal. I run mine on the loose side, if they squeal I tighten them up, just a little... and keep doing that until they stop squealing. Any more than that and you are just losing horsepower, putting unnecessary strain on the belts and pulleys.

Make sure that you do have the right pulley for the machine too.

Shaun

 

[defensiblespace]

Thanks Imagineero. I will try the fish scale method for checking the v-belts. They really aren't all that tight. It's the belt to the cutter wheel that called for something like 1/4" deflection at 120 lbs of torque. That seems awfully tight to me. I attached a couple pics of the belt at the top of the original post.

 

[defensiblespace]

I would check your pulleys and make sure you dont have a bur or a bend inside the track of the pulley that is rubbing the belt. If everything looks good there, I would check to make sure one of the bolts that holds the cover on isnt to long and is rubbing the belt. Looks like you have a bur or bent pulley though.

This sounds like a likely cause. I am did a minor adjustment on the jack shaft. I'm going to run it again today and see hoe it goes.

 

[stumper63]

That's 120 "inch" pounds, not "foot" pounds, just checking....

Stumper63

 

[defensiblespace]

That's 120 "inch" pounds, not "foot" pounds, just checking....

Stumper63

Ooh! Good call. I'll have to double check those specs. Thank you.

 

[defensiblespace]

That's 120 "inch" pounds, not "foot" pounds, just checking....

Stumper63

Sure enough, I tightened that belt to 120 foot lbs, not 120 inch lbs. That is a substantial difference. I thought belt seemed ridiculously tight. Thank you Stumper for the heads up.