Hi Ryan,

Slippage at the drive pulley occurs whenever the frictional forces between the belt and the pulley are less than the forces holding the belt stationary. I assume that you have not experienced slippage once the belt has started to move and the system has "warmed up".

Icing will interfere with the pulley/belt friction ratio and corrective action must be taken to counter the problem.

Your options include:

[1] The one you described with a "nubbed" metal pulley. The nubs dig into the bottom cover of the belt (similar to studs on tires for driving on ice). However, this also decreases the service life of your belt's bottom cover.

[2] The use of ceramic lagging. This works the same way as your pulley option.

[3] Using a snub pulley to increase the wrap on the drive pulley.

[4] Increasing the take-up tension. Be careful with this one -- over tensioning can cause mistracking problems, increase bearing failure rates, adversely affect the splice, and increase damage from loading.

[5] Heat the area around the drive to eliminate the possibility of icing. (This would be my choice, based on the information you provided.)

[6] Heat the drive pulley only.

You should also investigate the rest of the conveyor. If the belt has frozen to the idlers, skirting, and cleaners, your start-up load can be very high. This may require additional action on your part. ■

Ryan,

In my opinion you should look into the condition of the original lagging material as well as the condition of the overall conveyor.

By monitoring the power (Amps) drawn by the conveyor you can determine if some other factor is creating higher resistance to move the belt.

Also the rubber on the pulley may have hardned and its conditions changed substantially to cause the slippage.

Unless you changed the load or some other process parameter, it is difficult to understand that a conveyor performed well for a period of time and now needs to be modified.

I'm saying this because if you change the head pulley to a ceramic lagging or ribbed stell etc. without full understanding of the root cause for the current slipage you may endup spending large amounts of money without solving none of your problems.

Worst yet the life of the belt will decrease and your downtime will increase.

Antonio Reis

www.vitrom.com ■

I've seen this problem in most hog fuel belt applications in winter months. I have customers that are using a product called

"Liquid heat" it can be used on conveyor belts, steel chutes etc. without damage to belt. It is availabel in 55 US. Gallons. Most people use a small one gallon spray system to apply to belt etc.

It works quite well. Spray area of concern before start up. It also works very well in chip chutes etc.

You can find this product on WEB.

Ron Babin ■

Ryan

Ron Babin's suggestion would be a very inexpensive test and just might solve the problem. The web site for the product is below.

Mr. Babin, thanks for introducing this product to me as we also experience similar icing problems in Ontario and have gone through the major expense of ceramic lagging.

http://www.liquidheat.com/liquid.html

Regards,

Gary Blenkhorn ■

Hi Ryan, we use the product (Liquid Heat) on coal conveyors throughout Alberta to great success, you can contact me to get the product here in Alberta. By the way I'm pretty sure we went to U of S together.

(403) 243 5581 ■

I would be interested in knowing if the belt slippage is due to frost on the belt or frost on the pulley. If it is frost on the belt, I have seen a simple solution to this problem. Place a row of salt blocks contained with a metal structure so the salt blocks rest on a flat part of the non-carrying side of the belt. This will remove the frost very efficiently with little cost.

A word of caution about applying any chemicals to belts. Make certain the chimical is compatible to the rubber conveyor belt. If not the belt could end up cupping. A cupped belt looses contact with the rolls and may become impossible to keep on track. ■

Dear Mr. Goldbeck,

Does the salt concentration cause any concern for corrosion of structures and components (belt cleaners, idlers, et al)?

Most installations are not prepared for a salt concentrated environment. ■

These are salt blocks (like the ones used in water softeners or salt licks) that just rest on the belt and remove the frost. The amount of salt actually consumed is so small that the corrosion factor is non-existant. The salt blocks can last several months depending on belt speed. This is also environmentally correct. It would cost practically nothing to use this method. Most places it works very well. A few places I have recommended this the ICE was too thick and it would not work. ■