Your request cannot be answered in a straight forward response due to the complexity of the design. There are a number of points your have not included.

How much side travel (drift) is allowed and why?

Are lateral constraints applied, if so what are the criteria?

How much of the belt is not supported beyond the idler face?

Do you check for buckling and curling and so design the curves?

What about the idler junction flexure criteria?

There are many additional points that I will not elaborate on.

Some horizontal curves can be controlled in special ways that are practiced, but not published.

Some horizontal curves can use lesser banking angles ,with similar belt tensions, depending on the idler system.

Carry and return strands have been designed with over 30 degree banking angles with successful operation. This cannot be applied in the general sense.

Often, return strand banking angles can be over 15 degrees while carry sides are restricted to no more than 8 degrees. Why?

When using advanced longitudinal beam bending techniques, the belt can negotiate tighter banking angles with the same tension than results from standard calculating techniquies.

We do not provide engineering in the forum.

I don't get it. Why would a client risk giving a design to those with little expertise and subject the project to high risk and unecessary but costly decisions? ■

Dear YK,

My response seems a bit harsh. Why do we see this question posed? I paraphrase the question:

"Please Tell Me How to Engineer @ the Design Limit"

"Please Provide All Guidelines"

Some of us find this question is repeated over and over in the forum. As you see, no respondents. Yet, there are many who can give great detail. At what cost to those that create this knowledge? Some toil to advance designs through research, and then hope to apply the results of successful research as a business.

However, no harm in asking. ■

This observation is totally correct, perhaps only marginally harsh. Time & again we see postings where some earnest & able young soul with limited expertise is saddled with a task which their client/superior cannot perform himself/herself, nor even understand.

After opening replies with "Your request cannot be answered in a straight forward response..." we certainly finish up with a pretty straight forward closing line. Well said. ■

By Jupiter!

For heavens sake pay for a recognised qualified and experienced materials handling engineer to do a full dynamic analysis of the long curved overland conveyor, for all load cases and for all dynamic and running states , having first optimised the basic parameters.

These results must then be plugged into a proven dynamic curve simulation to optimise the idler geometry, banking and forward tilt for the horizontal curve as well as any vertical profile, for all weather conditions.

(It sounds like you are trying to "paint by numbers" here)

Anyway, for what it is worth, I use 20 degree return idlers extensively for my horizontal curves.

I know Gabriel L prefers to use 3-roll troughs on the returns for some curved applications.

Regards

LSL Tekpro ■

Dear all,

I understand your frustration with a number of projects going to design teams that do not have the experince you have.

However keep in mind there are no real books on these subjects for the younger guys to learn from. They use forums like this and journals to learn and to try and design as well as you guys.

It would be a shame if the tricks and clever design methods you have discovered over the last 40 years retire with you.

You don't have to tell them how to do it but just point them in the right direction.

So Jupiter,

The banking angle on the carry is limited by the product falling off. Anything you do to stop this will allow you to back further, providing other design critera are met.(Buckling etc)

The return banking angle is limited by the belt falling off the idlers. Any you can do to stop this happening will allow you to bank further. eg. Using a troughed idler, possibly inverted V return at some interval.

I am by no means an expert on the subject however I hope this is of some use and may at least get others to say I am wrong thus giving further insite on the subject.

Best Regards,

Gareth Blakey

blakeyg@conwag.com ■

First and formost, you have to determined the correct tensions for all steady-state and dynamic conditions before you will know the belt's movements and what banking angle to use. This includes influences from:

1. rubber compound & temperature wrt rheology & losses

2. belt construction- cover gauges & bending behavior in axial & transverse

3. idler trough configuration & roll diameters related to press.

4. pressures from all curve conditions

5. belt speed & its relationship to rubber losses wrt WLF

6. loading pressures on belt & belt-to-idler interface wrt ore

7. idler spacing

8. time-strain history & aging influences of rubber

9. surface conditons produced by factory

10. idler drag dependent on bearing, grease, speed & temperature.

These are the first 10 items that come to mind. There are many more.

If you know how these work, you do not need our help and the forum is of no consequence. I you don't know how these work, you need our help and the forum is not the place to find the answer. ■