CEMA limitations

TMSA Tecno Moageira Ltda. Brazil
(not verified)
Posted in: , on 12. Sep. 2007 - 18:43

Hi All

I would like to know what are the limitations for lenght, capacity and width for conveyors calculated by CEMA 5th and 6th editions.



Re: Cema Limitations

Posted on 12. Sep. 2007 - 08:48

Dear Emerson,

Very timely question more relevant to 6th edition. I write this as a member of CEMA, but not representing CEMA's position.

The 5th edition is based on details of the first five editions. The method and parameters did not change throughout all the earlier editions. What did change is curve fitting the Ky values into a set of emperical parameters.

All of the earlier development came from Hewitt-Robins in collaboration with Penn State University. The Ky equation was developed over a number of years starting back to 1953 and culminating with the Bonneville dam conveyor system test work outside of Salt Lake city.


CEMA is holding a special meeting Sept 18-19 to table this difficult question. Some in CEMA wish to use the advanced tension and power calculation and some wish to have the range and tolerances documented before releasing the method to the general public.

Like all things today, politics will need to be eliminated before meaningful engineering dialog can proceed.

Goodyear wrote a letter to CEMA with a request to advise or set limits that have been verified by respected CEMA technical members on:

1. belt width

2. belt speed

3. belt cover thicknesses

4. idler trough configuration (angles, roll lengths, roll diameters)

5. idler spacing

6. temperature minimum and maximum

7. belt crossectional loading

8. belt bending modulus to form trough shape (forming force)

9. belt length

10. material density

At present, most CEMA members do not know:

1. Kbir formula and parameter theoretical development

2. Kbir design limits and tolerances

3. testing matrix with known range and tolerances

4. testing verification by other CEMA member with documented accuracies and their influence on the final result

5. audit trail with consensus

6. what rubber properties Kbir is based on and can they be changed

7. instructions on use of Kbir parameters

We caution the use of the advanced 6th editionform. There are areas where it does not agree with known installation readings.

Lawrence Nordell Conveyor Dynamics, Inc. website, email & phone contacts: www.conveyor-dynamics.com nordell@conveyor-dynamics.com phone: USA 360-671-2200 fax: USA 360-671-8450