Dear Mr. Glenn Segers,

As I understand you want to know the means (devices) which can push the mis-aligned belt to the alignment.

The usual conveyor belts are not designed / suited to apply aligning force at belt edges. So, belt alignment cannot be achieved by providing constraints at the edges. Hence, belt alignment effect is to be created by belt contact with the idlers, in conjunction with gravity and tension in the belt. Following features create presence of self aligning force (adequacy of which to really push the belt is a separate issue).

1) Gravity action on V or trough shape

2) Forward tilt of side rollers in a trough idler set.

3) Skew placement of idlers to generate pushing force towards particular side of conveyor

4) Banking of idlers to create pushing force towards particular side of belt conveyor s

5) Conventionally used pivoted self aligning idlers. These actually utilize action described as per serial no.3. There are differing opinions about its use and effectiveness.

Topic somewhat similar to this has been already discussed recently in this forum in the thread "Self-Aligning Idlers" in forum "Belt Conveyor Technology", you may refer that thread for details.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Conveyor Dynamics, Inc. has designed many overland conveyors.

Our preference today is to use the same roll system as the carry strand for better belt tracking and belt edge vibration control(flap). There are benefits and drawbacks to this approach. Advanced engineering techniques are required.

Benefits are:

1. better belt tracking due potentially higher edge lift with smaller net junction angle (ie. 3-roll 35 degrees is better than 20 degree Vee which has 40 degree junction angle)

2. better belt edge vibration control allowing wider idler spacing - we have 10 meter spacings in operation and this can be increased

3. lower noise emissions due to larger spacing

4. lower and standardized roller inventory with one or to types

5. lower return replacement rate due to bearing size and lower vibration

6. need special engineering analysis and field experience of idler junction stress and its fatigue limit analysis coupling carry and return influences.

Drawbacks are:

1. idler junction stress and fatigue failure must be accurately assessed engineeried

2. may require two roll sized to alter anglular junction positions of carry and return strands

3. may have slightly higher capital costs

4. may require a belt turnover

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com ■

Another benefit not stated above is the ability to overlap rollers and the junction thereby decreasing the stress and fatigue levels of a two roller vee system.

LKN ■

Haste makes waste:

I must correct the added statement on the three verses two roll and call it the seventh benefit:

7. 3-roll trough allows the center roll to overland the wing rolls when the rolls are offset thereby eliminating the junction gap of a two roll system.

I make a typo in saying that:

"... decreasing the stress and fatigue levels of a two roller vee system." should state ... "level of a three roll system."

Sorry for misusing the forum space.

LKN ■

adding to benefits 1-7 with point 8, 9, 10 and 11 benefits:

8. reduces shell abrasion by lowering local belt weight and belt bending springback force near junction.

9. improves tracking by increased idler spacing which forces belt to conform to trough shape which increases wing roll weight leverage.

10. allows for forward tilt on return strand although we only recommend this only for extreme conditions in horizontal curve engineering where moisture is not an issue.

11. improves horizontal curve engineering with better control of belt return strand position.

I believe there are more points to this arguement. We can claim significant success with working installations.

LKN ■

We have used "tru trac" belt trackers for about two years now and are very happy with their performance on our 42" and 48" conveyors at 600 FPM.

Check them out at the link below.

http://www.tru-trac.com/

Gary Blenkhorn ■

Glenn

Distributor for tru track in Australia

ROJAN ADVANCED CERAMICS

17 Alacrity Place, Henderson,

Western Australia, 6166

Tel: +61 8 9437 1155

Fax: +61 8 9437 1156

E-mail: rojan@rojan.com.au

Web: www.rojan.com.au

Gary ■

Hi Glenn,

Suggest you take a look at the web site to AS techno-Track:

www.technotrack.no

We have a wide selection of belt trackers. They have never as we know of damaged any belt.

contact:

harry@technotrack.no

Regards

Harry Holtar ■

Originally Posted by Glenn Segers

Any one out there have a good suggestion for trackers. What is the real effect of vee returns. Is there a tracker that does not damage the edges of the belt. Can surveying practically assist with pulley and idler alignment. Any comments will be appreciated.

My new "low-cost rollers/idlers" are made out of RY-FULL-PLASTIC ( RY - means a very low-cost recycled plastic!) Because the material is "FULL" I can give them a twice-conic form or for the upper belt a conic form!"

If you give me your E-MAIL I will send you more informations abbout this inovativ rollers/idlers, because they have also many other features. I think, they will have in the future an important place at conveyors.

BlahaPeter (foerderschuettgut@arcor.de)

Rosenstr.5 D-85609 Aschheim near Munich/Germany ■