belts cracking

[grandmanitou]

Hi,

I have to disc mills of the same model here. But I have some problem with one: the belts are cracking faster and must be replace more often.

The two mills are exaclty the same and grind the same product.
I think maybe a deflection between the two sprockets could cause this problem. What do you guys think?

 

[svanels]

Alignment?
Worn out sheaves?
Dirt & oil ?
Wrong parts?
Operator abuse?

What is the time span between replacements?

 

[quark]

Another one,

Over tension

 

[rob768]

as well as under-tension (too much vibrations). Pollution (oil)? Temperature? Torsional vibrations from the motor?

 

[grandmanitou]

The two mill that I talked about are exactly the same with the sames conditions. It's the same mechanic that do both replacement of belt.
So, no over tension, operator abuse, under tension, oil, wrong part, temperature...
but it may be the sheaves, torsional vibration or something else...

 

[JJPellin]

For a cog belt drive with two flanged sprockets, I would be most suspicious of alignment. With two flanges sprockets the shafts can be out of parallel and the belt will ride hard to one side. This puts a greater tension on the fibers along one edge of the belt. For a big drive with one sprocket that has no flanges it is more obvious if the belt tries to track hard to one side. It will run off the edge of the unflanged sprocket. I have seen this with smaller cog belt drives. There are excellent laser tools for aligning sprockets. Or a skilled mechanic can do a pretty good job with a string and a tape measurer.

 

[unclesyd]

Is one of the mills close to a motor control or electrical switch cabinet?
If so, Ozone maybe the culprit.

One other possibility is if one belt is exposed to sunlight I read about a case where UV exposure was instrumental in drive belt deterioration.

 

[grandmanitou]

Sorry for my ignorance, but english is not my native language
what's a cog belt, a belt with teeth?

 

[grandmanitou]

We are using V-belt on these mills

 

[JJPellin]

Since you used the term "Sprocket" rather than "Sheave", I assumed you had a cog belt drive. A cog belt has teeth on the inside that engage grooves in the outside of the sprocket. This makes for a positive belt drive with no slip. The belt and sprockets are more expensive, but with no slip, they have greater power transmission capabilities and can be more reliable. The best known example of a cog belt drive would be the main drive for Harley-Davidson motorcycles. The drive to the rear wheel is a Kevlar reinforced cog belt. For a V-belt, my original comments probably do not apply. Sorry for the misunderstanding.