Don't shoot the messenger:

How old is the belt?

Your problem is not global its local, when was the last time the

belt was spliced? the belt fabric may be stretched.

Do you have a dutch man cut away edge on both sides of the

belt splices to allow for easier transition of the conveyor belt over

the pulleys?

Are the take up pulleys square in relation to the belt?

Are you using a training idler for every tenth idler -both

troughing and return.

Are the belts tracking properly? as in are the head pulleys true/square/level in their mounting?

Do you have lagging on the gravity take up pullies?

I would lean towards belt fabric stretching/failure if every thing else is in proper alignment. conveyor belts are no different than water or electricity they are lazy- and will do what they want unless the are restrained/controlled. ■

Hi,

Uneven wear such as this is caused by poor pulley alignment and is usually starts with the design of the gravity take up. Over time as problems occur with the take up (usually manifested by belt tracking problems that are very hard to rectify) operators start "correcting" the tracking by adjusting the alignment of other pulleys (usually low tension ones). These out of aligned pulleys will be worn unevenly by the belt as the tension across the face will not be even.

Col Benjamin

Gulf Conveyor Systems P/L ■

I'm not familiar with the term "Dutch man", could you explain that to me. ■

I think you willl find that since the product dust, waste, crap, abrasive etc.

1. YOU DO NOT HAVE A PLOW TO PUSH DUST OFF THE BOTTOM SIDE OF THE BELT AT THE TAIL PULLEY AND IT RIDES ALL THE WAY UP TO THE DRIVE UNIT AND THE FINES ARE WHAT IS WEARING THE PULLEYS.

(A) DOES YOUR TAIL PULLEY HAVE A SELF CLEANING BEATER PULLEY? If not get one as your product is the culprit.

(b) do you use silicone caulk to seal the splices? you should if you are not already doing so.

2. IF YOU DO HAVE A CLEANING PLOW ON THE BOTTOM OF THE

BELT BEFORE IT MOVES INTO THE TAIL PULLEY IT DOES NOT HAVE

ENOUGH TENSION OR THE PLASTIC PLOW IS WORN OUT ■

Greetings,

A belt dutchman is a triangle wedge cut away from the mechanical splice line at the edge of the belt to allow for easier transition of the belt over the drive, head, take up and tail pulleys.

The dutchman reduces tension on the mechanical splice or splices and increase the mechanical splices life, and it reduces edge pulling of the conveyor belt splice and in the process eliminates weakening the splice from one side to the other eventually ending splice failure if not found before hand. ■

Hello Chris..

It would appear, quite logically, that the lagging is wearing on the pulleys which operate on the dirty side of the belt.

The more the dirt, the more the wear, therefore check that the scrapers are not taking off the dirt on one side of the belt more than the other.

Regards

LSL Tekpro ■

I agree with the above assessments. I will add:

1. most often the one sided wear results from added shear stress or added abrasion which can come from differential pulley geometry, bad pulley alignment, or contaminants as noted earlier.

2. sometimes the added shear stress comes from the method of wrapping the lagging before autoclaving curing the lagging (hot vulcanizing) The wrap is applied in a spiral pattern to maintain pressure of lagging to pulley steel. It can lead to producing a lead screw action between belt and pulley. Pulley wants to misalign the belt, operator wants to align by other means such as restraints or misaligning pulley, which leads to unacceptable shear stress and premature failure of one lagging side. ■

Head pulley wear on the edges may be caused by the transition geometry from trough rolls to flat head pulley.

Please post or email a sketch of idler transition geometry and photos of the lagging damage? ■

Larry Nordell is correct, it is almost certainly a transition problem. You can make your own assessment by looking at how the belt is sitting on the last 4-5 rollers into the head pulley. When the belt is unloaded there will be a substantial gap between the belt and the centre roller. Your task is to re-align the idlers such that the belt evenly touches both the wing and centre rolls on all 5 of these rollers and this is done by packing of the idlers and ensuring the trough angle is slowly decreased through this section. This is a very common installation problem.

Cheers

Colin Benjamin

Gulf Conveyor Systems P/L ■

I would add a couple of points to Colin's remarks:

1. The type or geometry of the transition may vary such as in-line vs. elevated head/tail pulleys. Some transitions are more belt friendly when the idler packing is optimized.

2. Some transitions can be too short and thereby apply excessive pressure when the idler packing is optimized. A longer transition is always more gentle on the belt.

3. Restating the wrapping and autoclave curing of the lagging, without secondary grinding, can cause the pulley lagging to push the belt toward one side. The sideways thrust can be quite strong and requires restraints to keep the belt on the pulley. ■

Yet another point comes to mind:

Belt cover damage can occur in the inflection point between wing and center rollers depending on idler junction pressures and subsequent shear stress and squirming of the bottom cover.

Belt covers can be damaged near the outer edges from excessive vibration.

Belt covers can be damaged near one outer edge from pipe conveyor bottom strand riding upside down.

All these point lead to variations across the belt's neutral axis thereby can set up a damaging shear stress gradient across the pulley lagging. ■

To add to the already good comments, I will add a comment that baffled many competent people looking after conveyors. The locations of a few conveyors that had single side wear in lagging and also it was eventually confirmed that idler rolls were also suffering predominantly on the same side was no one thought to take into account the fact that the conveyor orientation was mainly East / West. The sun on the Northern side in conjunction with the predominantly Trade Winds from the South East was creating a 'Hotter and Softer' belting pliability on the Northern side so the belt in the southern side was tighter tensioned and the lagging was the first thing to wear down to the steel pulley surface leaving a circumference lagging 'Collar' on the South side outter edge of the pulleys. The wear eventually had the idler rolls with distinct grooves about 60 to 100 mm from the outer edge of the wing roll from the belt edge contact. Wind guards and shading helped control the issues. Off-Centre loading can also cause some of the issues described. This is just another thing that should be considered when designing a conveyor system. ■

Hi Dave,

I do not agree with "solving" this problem by using ceramic lagging. All you have done is transfer the problem to the belt, i.e. accelerated belt wear. It is about identifying the root cause and addressing this. If lagging wear is an issue due to poor contact with the dirty side of the belt then a good starting point is making sure the belt is clean. Generally a worn belt will not cause serious lagging wear with snub or low tension pulleys as the point of highest pressure will dictate the pulley rotation speed i.e. the edges with the centre not coming into contact. If however there is a transition problem or similar that sees the belt no longer "flat" then, yes lagging wear occurs, especially with steel cord belts.

Cheers

Col Benjamin



Gulf Conveyor Systems Pty Ltd ■

I have seen uneven wear on pulleys which was caused by a combination of a bit of pulley misalignment (presumably as an attempt to train the belt), combined with a bit of pulley edge crowning.

This gave one edge all the training work to do, thus giving uneven wear.

Cheers

LSL Tekpro ■