Hi all,

It seems to be a good idea to put harder top covers and softer bottom covers to the belts, to gain the advantages of both properties.

Softer bottom belt covers would maintain good contact conditions to drive pulleys and good conditions also for belt alignment, and the lifetime of belt would be helped due to its harder covers.

Have some of you already made this trial??

Regards,

Alexandre Calijorne ■

Dear Alexandre,

Hard top cover does not necessarily mean longer wear life. You need to know the damage mechanism with both polymer and carbon black details. Whether the damage is predominantly gouging or abrasion or some combination and what the chute design is contributing.

Soft bottom cover is probably a very bad idea unless it is coupled with knowledge of the rubber's rheology and other associated energy loss factors. Soft can mean tending toward plastic behavior which is the worst thing you can do. You must become knowledgable about the rubbers rheology and its viscoelastic properties for the given installation and the working environment. ■

Dear Louis,

Pulley lagging temperatures have been measured. The typical increase in rubber lagging on drive pulleys is between 5 and 10 degrees above ambient when the ambient is about 20-35 degrees C. We performed the measurements when a drive lost traction on a 7000 kw system and the slip melted the lagging.

I believe I posted some details on another thread so years ago? Anyway we determined the need to maintain sufficient grooving in the lagging. Did the FEA on lagging deformation with various groove patterns and depths to determine how hydroplaning works and how the rubber lagging is distorted and how it is destroyed by high torque and belt tension. As a part of this study we were able to model the rubbers deformation in a viscoelastic model which then could be converted to energy lost = heat generation = heat rise to a new thermal equilibrium. ■

Dear Lawrence,

Yes, I have to know more about the issues you´ve mentioned.

And I forgot for a while that a softer belt cover can means higher values for the artificial friction coeficient.

Thanks.

Alexandre Calijorne ■

Dear Alexandre,

What do you mean by "artificial friction"? You sound like a doubter.

Viscoelastic analysis is true to the physics of the universe. No doubting, just science. You measure, apply, and seen the accurate results.

When some cannot measure and apply with consistent, accurate, and comprehensive results they resort to name calling, using magical potions to ward of the truth, and instigate doubt in the uninformed. This comforts them and allows them to practice, where otherwise they would be seen to be technically deficient, and be labeled heretics tour science.

“Artificial Friction” has been used by some authors in a accurate portrayal of rolling frictions “Ky, Kx et al” that are truly phenomenological measures. CEMA and DIN are standards that apply phenomena. These measures are based on statistical averaging that trend results to known dimensional properties.

We know today they are truly guesses and as such can produce mistakes of significance. They leave off many fundamental sciences. The science of rheology swiftly advances. Today, 50% reduction in rolling resistance losses are real, not fiction. This is especially important as belt length, tonnage and speeds are pushing new limits.

Some Universities are now becoming believers. They seek funds to investigate the science for its rewards.

Just wait and you will see their claims of “artificial” and “fiction not fact” will cease ■

Dear Lawrence,

So, I simply repeated an expression I found in some references...just a distraction.

I also have no doubts, about the importance and advantages of the applied science.

No chances in to produce reliable and competitive equipment without such science.

Thanks.

Alexandre Calijorne

Dear Alexandre,

What do you mean by "artificial friction"? You sound like a doubter.

Viscoelastic analysis is true to the physics of the universe. No doubting, just science. You measure, apply, and seen the accurate results.

When some cannot measure and apply with consistent, accurate, and comprehensive results they resort to name calling, using magical potions to ward of the truth, and instigate doubt in the uninformed. This comforts them and allows them to practice, where otherwise they would be seen to be technically deficient, and be labeled heretics tour science.

“Artificial Friction” has been used by some authors in a accurate portrayal of rolling frictions “Ky, Kx et al” that are truly phenomenological measures. CEMA and DIN are standards that apply phenomena. These measures are based on statistical averaging that trend results to known dimensional properties.

We know today they are truly guesses and as such can produce mistakes of significance. They leave off many fundamental sciences. The science of rheology swiftly advances. Today, 50% reduction in rolling resistance losses are real, not fiction. This is especially important as belt length, tonnage and speeds are pushing new limits.

Some Universities are now becoming believers. They seek funds to investigate the science for its rewards.

Just wait and you will see their claims of “artificial” and “fiction not fact” will cease ■