Hi,

Yes I have come across this situation before where installations were done poorly. In the low tension areas it may be possible to sort the problem by banking the idlers but this will be at the cost of maintenance. In the high tension area where I have come across this problem twice you have to rectify the alignment

Col Benjamin

Gulf Conveyor Systems Pty Ltd ■

We must assume the initial installation was done correctly. The kinking was not on individual idlers, but on the overall support structure.

You should not be packingv(banking) the individual idlers. You should be packing or aligning (banking) the stringer frames or its supporting structure to counter the major steel work error.

The idler frames maintain the general alignment of the idlers to belt . Therefore we do not adjust for major installation erros using the idler frames.

I have seen a number of installation errors that lead to installing a unsolicited horizontal curve. In concept your appraoch is correct. At least you did not take your hammer to the idler frames and cock-knock them into oblivion. ■

Well done Nishant...

I hope your solution will suffice for all conditions of loading and weather though.

Had you not done pretty much what I was initially going to recommend anyway, I was going to suggest additional remedy of putting the next size up idlers on the carry side, but to the same stringer centres.

Regards

LSL Tekpro ■

I ran into a similar problem about 25 years ago. We were installing new conveyor galleries and as we were about to join the sections before lifting them into place we noticed that each 140' section had a horizontal curve of >6". When we queried the fabrication shop on their fabrication methods, we discovered that the side trusses were fabricated on their side on the floor and that the floor was not level; it actually had a hump in it. And the shop hadn't bothered to straighten the trusses before welding in the upper and bottom chords. As we were on a tight timeline, we couldn't insist that the fabricator supply new galleries. Fortunately, with some good round-the-clock field cutting, gussetting and re-welding the fabricator was able to reduce the gallery curve to acceptable amounts. Once the gallery sections were up in place, we cut the stringer sections free from the gallery, aligned and re-welded them. The belt conveyor is still running today.

It was one lesson that neither I or the fabricator will likely forget.

Paul Janze

Sandwell Engineering Inc.

Vancouver, BC Canada ■

If you skew the return idlers by rotating the idlers out of alignment, take care when it rains and the necessary skew friction is reduced. The belt will then mis-track. Better to gain all alignment with banking if possible. ■

You can correct the error, as did Mr. Janze, or you can adapt and live with it.

The former is recommended, in which case belt training is pretty straight forward, always to center the belt on the conveyor's straight longitudinal axis.

If you choose to adapt to the error, by creating a horizontal curve, then it's back to engineering. You must survey and determine the actual geometry and, accordingly do a new set of design layouts and corresponding conveyor analysis. If the resulting horizontal curve is significant then you will have to analyze the belt wander that corresponds to the varying loadings and tensions. Belt training will not be straight forward (as with a straight conveyor), rather it will be towards a targeted belt location, not necessarily on the idler's center, according to the prediction of the belt wander analysis.

Joe Dos Santos ■

Hi,

I know it is a little late but if you have any tracking problems then take contact with AS techno-Track in Norway. We have a lot of differnet Belt Trackers since that is our speciality.

See us at

www.technotrack.no

or send us a mail at:

post@technotrack.no

Reegards

Harry Holtar ■

Originally Posted by pjanze

I ran into a similar problem about 25 years ago. We were installing new conveyor galleries and as we were about to join the sections before lifting them into place we noticed that each 140' section had a horizontal curve of >6". When we queried the fabrication shop on their fabrication methods, we discovered that the side trusses were fabricated on their side on the floor and that the floor was not level; it actually had a hump in it. And the shop hadn't bothered to straighten the trusses before welding in the upper and bottom chords. As we were on a tight timeline, we couldn't insist that the fabricator supply new galleries. Fortunately, with some good round-the-clock field cutting, gussetting and re-welding the fabricator was able to reduce the gallery curve to acceptable amounts. Once the gallery sections were up in place, we cut the stringer sections free from the gallery, aligned and re-welded them. The belt conveyor is still running today.

It was one lesson that neither I or the fabricator will likely forget.

Paul Janze

Sandwell Engineering Inc.

Vancouver, BC Canada

I don't doubt the accuracy of this reply, but it does intrigue me. If the side trusses were made with their insides up (normal for easier workshop cranage) then the curvatures from floor error should have cancelled each other out along the centreline, keeping the centreline straight.

I've had a refinery distillation column where the trays cleared the ledges because of shell distortion. Fabrication distortion is very difficult to predict. Does anyone have an example or suggestion to predict distortion using thermal FEA techniques? ■

Originally Posted by nordell

If you skew the return idlers by rotating the idlers out of alignment, take care when it rains and the necessary skew friction is reduced. The belt will then mis-track. Better to gain all alignment with banking if possible.

Request someone to explain the term " banking". ■

Originally Posted by sganesh

Request someone to explain the term " banking".

Banking is the term predominantly used to describe the provision of superelevation; particularly with regard to rail tracks along a bend. The outer rail runs higher than the inner rail to provide a counteraction to the centrifugal force. In conveying applications the 'inner rail' can be raised to counteract the local centripetal component of the belt tension.

Skew is used to describe the practice of slackening the idler hold downs and pushing the idler forward with one's foot, in a safety boot of course, until the belt runs back on course. It is an effective method for minor corrections and, as intimated, it depends on the lateral thrust developed between the belt and the slewed roller. ■