Belt Troughing

Posted in: , on 15. Jul. 2009 - 06:51

Dear All,

As you know, the return V idlers are frequently applied, and some miners or consultants are showing their tendency in to use high thickness covers, aiming to achieve more lifetime for the belts.

At the same time, the use of more robust and heavy belts turned also to be a tendency, due the higher capacities and longer distances demanded for a economical mining and transport of ores.

My question is about the conformation and contact between such rigid and heavy belts and the V shaped return idlers.

I am feared that, in some cases, the V idlers can be worst for the belt conformation than the triple upper idlers.

By the upper idlers, the central roll "give" more space for the belt conformation.

And because of the rigid and heavy belts, the contact between rolls and belt can occurs in a very, small contact length, causing damages not only against the idlers, but also against the belt cover.

The belt catalogues bring only references to the upper idlers conformations, they do not take the lower idlers in account.

And rubber rings when applied at the under idlers appears to be another weak point in this system.

Have some of you already experienced such questions?


Alexandre Calijorne

Alexandre Costa Calijorne Caltra Projetos & Consultoria Ltda [url][/url] [email][/email] phone/fax: +55 31 2555-9097

Belt Cover Thickness

Posted on 15. Jul. 2009 - 07:37

Some designers pick heavy covers to hide their lack of knowledge of what the covers do and how to design for reasonable cover life such as:

1. Proper feed chute design can increase belt life up to 10 times the norm.

2. Sufficient top and bottom covers to meet client life expectancy and no more

3. Sufficient rubber to mitigate rubber damage from excessive localized strain growth between idler and tensile member

4. 3-rolls are always better for the belt cover than 2-roll Vee or one roll

5. Control belt flap excitation that induces structural failures, premature bearing failures, and idler junction damage to belt covers.

6. Excessive cover increases bending stiffness that may inhibit sufficient contact with the rolls to provide proper tracking control.

Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: phone: USA 360-671-2200 fax: USA 360-671-8450

Re: Belt Troughing

Posted on 17. Jul. 2009 - 10:44

Dear Nordell,

Thanks for your comments.

Here in Brazil, few years ago, it was common to apply belt covers like 5 mm upper and 1,5 mm under, for textile belts.

Today, the "standard" turned 10 mm upper and 3 mm, imposed by technical specifications from some important customers and consultants. without relevant questioning.

Unfortunately in this case a technological retrocession happened.

A good and profitable task would be a re-lecture from some specifications and "truths".

Alexandre Calijorne

Alexandre Costa Calijorne Caltra Projetos & Consultoria Ltda [url][/url] [email][/email] phone/fax: +55 31 2555-9097