Mis-Tracking Forces
Dear Barry,
You are very right about this being a complex issue. Unfortunately there are too many sources to quantify the force by looking to the root cause so the only approach is to look at the amount of force required to deviate the belt from the idlers. This is a factor of belt weight, idler configuration, trough angle, load/unloaded issues, troughability of the belt (i.e. the amount of belt to idler contact), frictional forces between the belt and the idlers (contact length, surface friction) and finally the tension in the belt (the higher the belt is tensioned, the more the force required to deviate it from a normal path). We have developed some simple models as part of training courses we have delivered but have only gone into it in more detail when we have a specific problem that we had to report on. It will be interesting to see if there is quality published material of a general nature as I have never come across it and I have been in the industry a long time.
I suggest you look at each case on its merit. You will be surprised at how little force is required to deviate a belt is some instances and remember the belt requires some balancing inertial force to retify any mis-tracking. A very interesting study I did a long time ago was on 4 roll idler system. Such an in-line configuration can configure quite well to the natural catenary of a belt and as a consequence we found wind pressure alone would cause this belt to run off the structure ( a heavy steel cord belt). The fix in this instance was to go to a 3 roll system so as to break this natural catenary. It was this study that confirmed for me why you only design systems with 3 or 5 trough rolls in most applications.
Col Benjamin ■
Re: Quantification Of Belt Mistracking Forces
Barry
This is an excellent question. As you have noted quantitative answers are what we really want but they are in short supply. I've searched for the literatre you've described but found nothing on-line to date. Perhaps in the printed journals there is something.
I have often pondered this question too. The way I see it is that tracking of a conveyor system can be seen as a summation of the traking forces, both positive and negative. The amplitude of these elements varies, for example the tracking force due to gravity on the belt sitting in a trough idler is a small positive number whereas the tracking force of a tracking idler frame will be greater. The mistracking force of a poorly loading chute will be large whereas the mistracking of a siezed roller may be small.
If these elements could be quantified, it would be reasonable to start making some predicitons about how to fix a tracking problem at the minimum cost. For example: If a chute were loading poorly, is it cheaper to fix the chute or install a tracking frame?
I appreciate that the above comments make some very broad generalisations and I do sympathise with Col's comments about taking each system on its merits. However if there were quantification of these issues, it could only help. ■
Re: Quantification Of Belt Mistracking Forces
The simplest inspection and quantification of mal-tracking can be determined by applying horizontal curve engineering. This will provide about 80% of the forces as they are dependent on:
1. belt centeriline error from first installation or from settlement
2. poor chute loading symmetry
3. idler alignment error and friction between belt and rollers
Other facors are harder to quantify such as:
4. poor belt internal construction
5. errors induced by belt memery and pulley alignment
Belt tracking is a probelm in physics and the answer requires some basic knowledge of the physics at work.
Some basic measurements can isolate the various factors and aid in resolving how to control errors in tracking. It is not rocket science. ■
Re: Quantification Of Belt Mistracking Forces
I have made a detailed analysis about the various aligning forces that can be created to counteract the mis-alignment. The information and derivations cover about 18 pages of information and equations. The interested parties can write to me about this.
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 ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Mulani,
I will be most happy to get a copy of the calculation method from you and shall email you separately on this.
Meanwhile, I was just wondering if we can approach the problem from the opposite end i.e. instead of working out all the individual forces contributing to the misalignment, whether we can figure out the nett force/bending moments required to bow the belt into a certain shape. The basis of this method hinges on the fact that the belt has a lateral stiffness that resists and counteracts any attempts to bow it. The other thing, of course, is to figure out how the running tensions factor into the calculations bearing in mind that this will not be a linear, but perhaps some fourier, function over the length of the misaligned portion.
I must concede however, that this method will only be valid as long as the belt is not rubbing against any part of the conveyor structure, training idlers, return idler brackets or chute walls. Also the calculations will only provide a nett lateral force but will give no indications on the magnitude of each contributing factor.
Will appreciate your comments.
Barry Chung ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Barry Chung,
I appreciate your keenness to tackle the belt misalignment and alignment issue. I draw your attention to the following basic points which will be of help to you to decide your course of action :
1) The moving belt is in contact with idlers.
2) The moving belt is in contact with various pulleys
Therefore, the aligning forces which we can apply to belt, should come through above mentioned two items. Accordingly, generally following measure are adopted (these are just points in brief) :
1) Adjusting the pulley positions to train the belt.
2) Providing camber on pulley wherever it is not objectionable
3) Adjusting the idler orientation in vertical plane.
4) Adjusting the idler orientation in horizontal plane.
5) Etc.
The above are remedial measures to solve the problem which is being faced by the user. The fundamental requirement is that the belt conveyor fabrication tolerance, installation tolerances, quality of belt, quality of belt vulcanising, quality of idlers, and quality of pulleys, if are proper, then the belt once placed in its position should run true to alignment. As it is said by the experienced people, the belt will maintain the position due to frictional opposition to its deviation.
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 ■
Quantification Of Belt Mistracking
Dear Mr Chung,
I have to strongly disagree with Mr Mulani. One very basic of conveyor belt design and maintenance is that a pulley must be square to the direction of belt travel and therefore should not be used to track or correct any directional misalignment of a conveyor belt. In some instances we can, at low tension areas and then only with fabric belts, use crowned pulleys but these are about centralising belt travel rather than correcting mis-alignment. The ramifications of not having the pulley square to belt travel can be:
1) Distortion of the carcass of the belt particularly with a steel cord belt that ultimately means the belt will be changed out prematurely.
2) Uneven pulley face wear. I have seen significant abnormal wear even in steel faced pulleys.
3) Bearing failures in pulleys as the labarinth seals are open to dust and dirt
The first course of action at all times when you have a tracking problem is to find out the root cause, not use conveyor hardware to band aid the problem. Using idlers and tracking frames is a last resort not a first resort. It is on this basis that any quantification of the tracking forces must focus on the root cause, not the potential solutions.
Thanks
Col Benjamin ■
Re: Quantification Of Belt Mistracking Forces
G'day Col,
I fully agree with you that we should never band-aid problems nor, in resolving one, create another. Unfortunately, as I have often found, this is a difficult proposition. Identifying the root cause and finding the right cure are the easy parts. A lot tougher, is convincing the client (or management) to accept the cost. The final solution inevitably ends up as a compromise, using the limited tools available to offset the problem.
That being the real world, the larger question we should be asking is, what value can we derive from knowing these forces? From a practical standpoint, I would say not much, because the available body of knowledge on the why's and how-to's is so wide and overbearing that it makes any effort on this look rather academic. Still, I believe, as Matt has said, someone's got to put in the numbers.
While this may not be rocket science, which, by the way, the world knows more of than this, I think the beauty of the math alone is going to make this a worthwhile undertaking, never mind the practical value of the conclusions for now.
Barry Chung ■
Belt Mistracking Forces
Hi Barry,
I agree that it is always nice to put empirical evidence before a client especially one who does not want to spend any money. I think it is also true that once you fully understand the fundamentals of what makes a belt track off and how to systematically work out what the actual cause is, the cost of the fixes expecially when compared to the sustainable savings are quite modest.
All the best
Col Benjamin ■
Re: Quantification Of Belt Mistracking Forces
Amen Colin,
Which of these points should be discounted:
a) cost will bury the cure,
b) no real savings in lost capacity,
d) no savings in damaged equipment,
e) maintenance personnel do not tire of constant fixes
f) maintenance costs and time reduce plant effectiveness
g) imagine the comminsioning team telling the client to accept the obvious flaws with a new machine
h) knowledge of the root problem is difficult, not solvable, inconvenient, ........ ■
Mistracking Forces
Well and cryptically put Larry, and the answer is everyone
Col ■
Re: Quantification Of Belt Mistracking Forces
Dear sir
In my openion
In my openion before attampting to pulley displacement for belt tracking at the time of conveyor commissioning following should be checked
1.0 All pulleys must be square to the direction of belt travel each end every roller along with pulleys should be checked for correct allignment
2.0 Chute should be properly designed for central feeding of material on belt.
3.0 Incase of different materials are conveyed or conveyor is having variable speed adjustable diflector plates should be provided to avoid off centre loading on belt.
4.0 Check counter weight to ensure correct tension of the belt
A R SINGH ■
Re: Quantification Of Belt Mistracking Forces
Shree Singh,
Although what you have said is perfectly true, the causes for belt misalignment are so numerous and far flung, that we are often compelled, save a few, to accept deviations from these tenets in providing the cure.
Almost all misalignment problems can be attributed to any one or a combination of any of the following.
1. Attrition of the rolling elements and the belt. Here, we are not just talking about uneven surface wear but also variations in the strength and permanent stretch, over time, in both the longitudinal and transverse sections of the belt. Try laying an old worn out textile belt on the floor and notice how its rippled! These changes act eventually to throw the traction forces off-balance, which explains why a centred belt will not stay that way forever. Just how long it manages to do so is really a combination of many factors.
2. Operation and maintenance. Prevalent in cases where there are large load swings, the belt alignment will drift accordingly in response. This is because the traction forces are not a constant but are really tied in to the belt tension. Therefore, a belt centred at 2000 tph will very likely have a different alignment at no-load. Designers usually try to work around this by installing auto tracking devices. However, depending on how efficient these are, alignment swings generally worsen with equipment age. The cure lies in narrowing the range within which the belt is permitted to wander. Maintenance factors that contribute to misalignment include crooked joints and caked material (either on the spill plates, directly beneath the return belt or on the rolling elements) but these are usually quite easy to spot and rectify.
3. Faulty design and equipment selection. For me, this is the third biggest cause for belt misalignment with bad concave point design topping the list. Why not off-centred loading, you ask? Well, alignment problems associated with loading points are usually localized and are quite easily spotted and corrected by installing or adjusting the baffle plates in the chute or, if necessary, installing baffles after the skirtboard to redirect the flow. Bad concave point design, on the other hand, together with undersized take-ups, affects belt alignment over much longer distances and with more serious consequences. Just as overtension is bad for the belt, so is undertension for alignment, and is often overlooked. A permanent belt float at the concave point is a dead giveaway. Analysing the problem requires us to have an understanding of the relationship between the mistracking forces and the running tensions, which unfotunately, is not very well described in the literature, and also the reason why I have brought up this quantification question.
4. Poor workmanship during construction ranks number two on my list. A belt conveyor can be a very big structure and not easy to put together right. Imagine trying to meet the tolerances when constructing a half kilometer long conveyor in a warehouse with an 8 ton tripper car 30m in the air. Mismatched levels and centrelines, verticality problems and runouts are just some of the daily issues to be resolved, at times with ill-conceived patch fixes (like pulling hard on the frames and trestle legs to match the bolt holes), finally resulting in the structure performing in ways it was never designed to. Works fine for a while though, until the local pent-up stresses get redistributed and you end up with crooked conveyor and a serious misalignment problem.
5. Top on my list, the leading cause for belt misalignment (talking about long conveyors here) is permanent structural movement or displacement. Idlers and pulleys do not, by themselves, change their orientation. It is the structure that does this. As described above, structural movements can result from poor contruction. More often it is also caused by a settling, or worse, sinking, of the foundations. This is especially true of yard conveyors constructed on poor soil or on reclaimed land. Another cause for movement may be the gradual weakening of a particular section of the structure, which is exposed perhaps to greater corrosion. Structural movements, whether lateral, vertical or both, are usually diificult to detect by visual inspection but requires accurate survey measurements.
As you can see, the possible causes for misalignment and their corresponding cost of rectification are very wide. As professionals, our job is to identify the root cause, propose the best cure and to advise on the consequences. The rest is really up to the client (or management). Hope this has given you a better perspective.
Barry Chung ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Chung,
You state there are three main reasons for mal-tracking and other minor causes. You also claim there are numerous reasons for misalignment and cures naming 5.
I have seen and corrected tracking on many kms of belts and installed many 100's of km with straight and curved systems. I cannot recall a belt that does not track well, save significant factory or splice internal flaws, if installed well. When it wonders, is easily corrected. I am aware there are belts that do not track well. When these belts are studied in detail, their cause and effect behavior can be determined by applying basic physics.
Your point 1: I say is a rare event , at least for me. I have been in the field observing many hundreds of conveyors since 1968. I dont dispute your claim, but I have not seen this type of wear cause significant mal-tracking. I have seen large belt center wear that causes damage to belt cleaners that allows material carry-back and return strand build-up that forces the belt off-center. The obvious remedy is to replace the damaged belt and belt cleaners.
Point 2: Large load swings produce mal-tracking when the load does not center and/or applies higher pressure on one load station wing roll over the other. Large load swings can vary the tracking when the internal belt tension member construction is shown to be non-symmetric. THis can be determiined by side wand measurements that measure side travel due to construction flaws and is highly repeatable near a low tension zone. THis would be my number one point for bad tracking, given the belt/idlers were installed correctly. Many operators and engineers do not understand the physics and thus do not see the cause, only the effect.
Point 3: You seem to be talking about significant belt lift off the idler set. Yes, it can and does happen but is it chronic? Virtually every tripper has this problem yet they are, for the most part, able to track well even with some windage and belt swing. There is an old adage about tracking with the center roller. If it does not contact the belt for all conditions, the belt may not track well. This bit of physics is understood and correctable unless the belt construction is too stiff.
Point 4: Any constructor that cannot align the idler roller sets after installing the structure should not be in the business. Any monkey can deliver monkey busniess. Hopefully, the client selects a reputable firm to make the proper installation and that the contractor acknowledges slight correction of idler alignment are required to adjust for structural deviations in a similar way to earth settlement.
Point 5: Settlement happens. It can easliy be observed and corrected. Surveying is a validation tool. Modern overland conveyor installations have built-in corrective features for earth selttlement. Corrosiion and structural compliance is a big stretch - no pun intended. When this happens I would be running from the structure.
You do not discuss catenary idlers and their mal-tracking behavior. Also missing is the notion of close idler spacing can cause belt tracking grief.
Truthfully, I dont get your arguement on the mystery and complexity of belt mal-tracking analysis and difficulties of corretive action. ■
Quantification Of Belt Mistracking
Dear Barry,
Going forward from Larry's posting, a lot of the causes you detail for belt mis-tracking are as a result of rather than the cause. Back to the issue of addressing symptoms rather than root causes. I run courses on belt tracking and training and have been walking and looking at these sort of problems since 1970. The major root causes of tracking problems that I have seen are:
1) Poor loading of the product onto the belt. This can either be off centre loading or loading that has a sideways momentum
2) Insufficient counterweight leading to excessive belt wander.
3) Material spillage and build up on components
4) Idler bearing failures and/or poor idler maintenance (particularly around transfers -impact idlers)
5) Poor structual installation ie vertical and horizontal alignments are out.
6) Mis-alignment of key components (particularly pulleys)
7) Conveyor belt splices that are not square.
8) New belt that has an uneven surface or a bow due to the carcass fabric being tighter on one side of the belt relative to the other - this is a particular problem with fabric belt that has been slit from a slab roll.
9) Second hand belt that has a history for instance refurbished steel cord belt that may have had one edge trimmed due to cable damage.
10) Severely damaged belt for instance a steel cord belt that has a major puncture wound with broken cables on one side of the belt.
11) Spillage and build up on gravity take-ups and/or poor lubrication, maintenance of the runners on the gravity tower
12) Belt improperly shielded from a prevailing wind
13) Poor transitions creating abnormal pulley wear and/or belt surface wear issues over time ( this does not normally manifest itself as a tracking issue until you instal a replacement belt)
There may be a few others that I have forgotten. Most other issues eg systematic improper lagging and leading of idlers, belts and pulley faces with abnormal wear patterns etc are usually symptoms of he above , not causes. The art of tracking and training a conveyor belt is having methodologies and procedures that allow you to identify systematically what are the root causes from all the chaff and heresay around you.
Hope this helps
Col Benjamin
Gulf Conveyor Systems ■
Re: Quantification Of Belt Mistracking Forces
YES COLIN,
Adding to the mix of experiences with esoterics are:
1. Cross belt windage
2. Thermal growth from the suns preferentially heating of one side
3. Moisture from one side such as wind and rain when employing idlers with forward tilt
4. Warpage during galvanizing idler frames causing frame twist
5. Belt scrapers with one blade bias angle
6. Gravity counterweight sled twist due to small L/W ratio
7. Training rolls with bad pantagraph action
8. Bad belt cover compound causing irregular wear on bottom cover
9. Too much red wine
I'll leave the tenth point to another. ■
Re: Quantification Of Belt Mistracking Forces
Where are Ozzies without voices: Gary James, David Beckley, Ross Mathers, Carl Wilson, and other rare birds?
They have over a hundred years of added experinces and tall tails. ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Nordell,
There is no mystery. In fact, I've even said finding the root cause/s and solving the problem are the easy parts due no less to our empiral knowledge and experience (as Col has listed and for which I have covered point for point) of the problem which is already so well documented.
If you had followed the thread carefully, I was responding to one of Mr. Singh's notion that misalignment can be corrected by just squaring off the pulleys and idlers. Tell me Mr. Nordell of anyone who can centre a belt simply by squaring off the pulleys and idlers on a conveyor with a displaced structure, and I'll show you someone who walks on water !!!
You keep on alluding to this being a basic physics problem. Save for Mr. Mulani, who says he has something written down and published, I would most certainly like to see yours. Perhaps this is the only mystery that still eludes me - no pun intended.
Barry Chung ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Chung,
My first response (3rd posting) gave you guidance to published references on the physics and supporting math for your "Top of the List" or leading cause of misalignment. The works of Grimmer 1963 and others published in BSH give the principles of belt tracking due to settlement and other imbalances (such as Dr. Harrison on tracking errors from belt asymmetric structural damage, Prof. Oehmen(sic) on strain computations in horiz. curves et al,).
I know not of Mr. Mulani's references.
I don't believe any of us have all the answers. Mr. Singh was offering his wisdom and see no need to dispute his comment unless he errors. I do comment, from time to time, and can disagree with the emphasis and importance on facts when the point is lost
Hopefully, among the chatter, some will find the relevance. ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Colin,
Referring to my earlier reply, I clarify as below, although the subject has already advanced very rapidly onto various issues.
In fact, my answer is already in line with your statement. The last summarizing statement of my answer mentions that the point mentioned by me are remedial in nature (i.e. under no option situation). But best approach, as per the information from reputed belt manufacturers of very long time experience, is to avoid such occurrence by proper care in design, purchase, manufacture and installation. This means, if reasonable care is taken in proper design, procurement and construction of belt conveyor, the belt once put properly will not create problem of unreasonable magnitude.
Also, such issues would pertain to belt conveyors of general nature. Naturally, long distance, heavy class or high performance conveyors are to be corrected by eliminating the root cause rather than peripheral remedial measures. In a steel plant or cement plant, if a usual conveyor is not behaving properly, I have seen plant engineers disciplining it by appropriate methods which we would say very crude in nature. They say that the plant and production cannot suffer just because of this! Quicker replacement of belt, idler as a consequence of these temporary measures do not matter in a particular situation.
It is to be also noted that a conveyor once created as an excellent conveyor will not be so all the time. Such excellent conveyor can suddenly exhibit improper behaviour due to replaced belt of remade joint or replaced idlers etc. and it does not signify that the said belt conveyor is perpetually defective. Therefore, the issue is subjective and is to be seen in an appropriate context. Such things are quite common in actual plants.
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 ■
Belt Misallignment
Dear Mr Mulani
I fully agree with your views. In running Plant Maintainace crew generally adopt these crude ways of alligning pulley as for them production is main issue
A R SINGH ■
Quantification Of Belt Mistracking
Mr Singh, Mr Mulani,
As I have said earlier, I also spend a lot of time on sites and do a lot of training of maintainers and operators. The subject of belt tracking and training comes up very frequently and is a major problem at most sites. It is due to very poor site knowledge about how to go about the task of properly aligning and tracking a conveyor belt. The consequence is a series of band-aids that cumulatively usually have disasterous results for key components such as the belt, pulley lagging, structure, etc not to mention ongoing maintenance of such things as spillage etc. In many instances that I come across the persistent tracking problem whose root cause was not indentified correctly in the first place, has been subject to a series of quick fixes to maintain production. The end result of such frustration is usually using key pulleys to "correct" the problem. This is particularly so if the tracking off is tripping drift limit switches at the driveheads. Once someone starts fiddling with pulley alignments the consequential damage starts becoming a lot more serious as once again it is only a matter of time before the pulley face will be worn abnormally and the tracking problem will re-occur. This is why, as soon as I see that an operator has mis-aligned pulleys the alarm bells start ringing. It is very simply extremely bad practice and symptomatic of a site where they do not know how to track and train a conveyor.
This posting started off with Barry Chung seeking to quantify the mistracking forces. It is now covering the myriad of reasons why mis-tracking occurs and given the breadth of what we have covered I think in some respects we are also showing how complex the problem can be and therefore how difficult it can become to set up a series of empirical equations that will cover all circumstances.
All the best
Col Benjamin ■
Re: Quantification Of Belt Mistracking Forces
Dear Gentlemen,
As Mr. Nordell has admitted, none of us have all the answers and I cannot agree with him more.
Those of us who are fortunate enough to be frequently called upon to resolve chronic problems tend usually to speak from the point of view of our own ingrained knowledge and experience, which is why I was careful to label what I said as being "my" list. For which, the bulk of mine comes from working with large-scale yard and plant conveyors that are often long and steeply inclined, span between tall structures, carry corrosive and abrasive loads and among them, some are actually built on soft dodgy soils where, structural deviations and higher service factors figure more prominently to the problem compared to say, long overland conveyors with short stubby leg and lower service factors.
What we should not do, as professionals, is to trivialize or brand as irrelevant, the opinions and experiences of others, simply because what we know does not include or cover what the other guy just said. Instead of being dismissive (and abrasive - no pun intended), we should at all times, be willing to listen and evaluate and if we do not agee, forward our opinions in a polite and cordial manner. After all, forums like this serve to educate and provide a channel for altenative views. This being the internet, we must also be constantly aware that there are regional differences not only in terms of practices and attitudes, but also the standards to which we are able to hold our clients to.
Back to the issue at hand, what I have previously described is actually drawn from my own field experiences. The fact that my services are called upon, is that the problem is usually beyond what plant engineers are able to diagnose and resolve and definitely not of garden variety. Not matter how far fetched they sound, the cases are real. Take for instance the one I mentioned about a section of the conveyor being progressively weakened atually occurred on three conveyors where one end was located near the outfall of the seawater cooling system in a power plant. As the seawater is dosed with acid to impede barnacle growth, the spray from the outfall carried by the breeze gradually corroded and weakened the nearby structures. Since the other end of the conveyors were steeply inclined, the weakened structures suffered greater deflections resulting in a serious misalignment problem.
I have no wish to redefine or challenge our written knowledge, but I certainly hope my views will provide a different perspective to those trying to figure out their problems.
Best regards.
Barry Chung ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Colin,
I am in full agreement with what you are saying. In a philosophical language, one wrong creates many wrongs or (one lie compels to commit more lies) i.e. when tracking problem is attended in a wrong way, it will culminate into more wrong actions.
As I said in my first reply and subsequent reply, people should maintain proper quality of all the activities to avoid the problems. In no way, I am supporting the quick fix solutions, but I have only mentioned what people are often / sometimes doing.
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 ■
Re: Quantification Of Belt Mistracking Forces
If I understand the original request you are looking for references on the theory and calculations. There are many references. Some of the best references in my archives are:
- N. Basavanhally, et al: 'Dynamic Analysis of Steering Forces', ASME Publication 78-WA/MH -3
- N. Basavanhally, et al: 'Experimental Performance and Analysis of Steering Forces and Transverse Displacements in Troughed Conveyor Belts', Unit And Bulk Materials Handling, ASME Publication, 1980 pp. 37-45
- M. Egger and K. Hoffmann, 'Lateral Running of Conveyor Belts', bsh V21 N3, 2001
- M. Egger: 'Lateral Running Behaviour of Conveyor Belts with a Belt Conveyor', Phd Thesis TU-Wein, 2000 (in German)
- C.Spaans: 'Stable Guiding and Centering Effects of Crowned Drums', bsh V10 N4, 1990
- K.H.Koster: 'The problem of Guiding Bucket Elevator Belts and/or Belts Travelling on One-Part Bearing Rollers', bsh V6 N1 1986
This is all pretty heavy reading. Good luck! ■
Re: Quantification Of Belt Mistracking Forces
Dear Mr. Tapp,
The material sure looks like the info I was seeking. I will definitely look them up. Thanks for the help.
Best regards.
Barry Chung ■
Quantification of Belt Mistracking Forces
I would like to know if anyone is aware of any articles or published papers that describe a method for calculating the forces that would cause a belt to mistrack by a certain amount. Most of the literature I have come across only provides a qualitative treatment on how and why belts mistrack but makes no mention on the relationship between the mistracking forces and the shape and length over which a belt mistracks. I have a hunch that if we can better understand and quantify this relationship, it would provide a much quicker diagnosis of any mistracking problems.
Pondering on the issue, it dawned on me just how complex such an undertaking would be. Besides the differences on how to approach the calculations for the carrying and return sides, one would also have to contend with whether the particular section of conveyor involved is horizontal, inclined or regenerative or a combination of these. Through my field experience, I have observed that such relationships do definitely exist and have developed some gut feel methods for diagnosing and cure.
To start off, is there a method for calculating the total radial force required to camber/bow a return section of belt by a certain amount and how would variations in the running tension over that length of belt and the catenary, factor into these calculations? And can we safely assume that, in the steady state, this radial force be equal the total mistracking force?
I would like to invite opinions from learned colleagues.
Barry Chung ■