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Thread: Conveyor Belt Slippage Due to Icing and Non-Lagged, Non-Slip Drive Pulleys

  1. #1
    Ryan Needham Guest

    Conveyor Belt Slippage Due to Icing and Non-Lagged, Non-Slip Drive Pulleys

    I work at a pulp mill. One of our hog fuel belt conveyors experiences slippage due to icing/frosting at the head (drive) pulley end. Although it is completely enclosed, it is primarily at outdoor temperature except for a short run towards the head pulley where it is in the mill at a temperature of about 20 deg. C. The icing/frosting occurs when the outdoor temperature is -20 deg. C and below.
    The head pulley is currently rubber lagged and does not use a snub pulley. I am considering use of a non-lagged steel surfaced pulley that uses rows of ridged steel on the face to reduce slippage. The pulley supplier (George Hill Supply Company) claims that it reduces slippage in wet conditions, as well as snow and ice.
    Does anyone have any experience with this type of pulley?
    Any other suggestions for eliminating this slippage?
    As a second option, we are also considering the use of a snub pulley to increase the arc of contact of the head pulley.

  2. 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.
    Dave Miller
    ADM Consulting
    10668 Newbury Ave., N.W.,
    Uniontown, Ohio 44685 USA
    Tel: 001 330 265 5881
    FAX: 001 330 494 1704

  3. #3
    Ryan Needham Guest
    Hello Dave,

    The belt actually slips during normal operation (with the system "warmed up"). Ice/frost forms due to the cold belt entering a warm, humid environment. So heating the belt or the area is probably not the best option (although it may have been if the problem was just at startup condition).

    The belt is operating with a maximum tension of 160 lb/in. It is capable of up to 220 lb/in. My preference is to not increase the counterweight though due to the other problems it could potentially create. So I guess the first three of the 6 options you listed are the ones I'll be considering.

    I just found out that there is another conveyor in the mill that used to have the same problem, but this was corrected using three methods (simultaneously):

    1. Ceramic lagging on the drive pulley (a soft start was also required for this to avoid ripping up the belt).

    2. Snub Roller.

    3. Winged tail pulley (to help knock ice off the belt).

    Adding this combination to the conveyor that I am working on would be expensive. I'd prefer to only have to do one modification. Since these were all done simultaneously, I don't know which would have been the most effective alone.

    I'm also not sure if I'd need a soft start if I was using a nubbed pulley. I don't know if it wears out the belt as much as a ceramic pulley during slippage. I've heard that the ceramic and nubbed pulleys don't decrease belt life significantly as long as they aren't slipping.

    Thanks for the input.

  4. 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

  5. #5
    Join Date
    Dec 02

    Slippage at pulleys in cold temperaturs

    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
    Last edited by R. BABIN; 30th December 2002 at 16:12.

  6. #6
    Gary Blenkhorn
    Bulk Handling Technology Inc.

    Professional Experience 40 Years / 5 Month Gary Blenkhorn has 40 Years and 5 Month professional experience

    Discussions 102 Gary Blenkhorn acceded to 102 discussions, Publications 0 Gary Blenkhorn Blenkhorn released 0 publications

    Know-How Design (317) Gary Blenkhorn used this tag 317 times, Belt Conveyors (135) Gary Blenkhorn used this tag 135 times, Software (56) Gary Blenkhorn used this tag 56 times


    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.

    Gary Blenkhorn

  7. #7
    Author Guest

    Liquid Heat

    In regards to my previous message on this product.
    Att: Gary Blenkhorn

    Gary, you mentioned that you were in ontario.
    You can get this product from:
    JCP Belting in Burlington ont.

    Contact: Jeff Smith
    Tel:# 905-336-7193
    Cell # 416-561-0712

  8. #8

    Belt Slippage Due To Icing

    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

  9. 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.
    Larry J. Goldbeck
    Martin Engineering

  10. #10
    Lawrence K. Nordell

    Lawrence K. Nordell

    President and CEO

    Conveyor Dynamics Inc.

    Conveyor Dynamics Inc.

    Professional Experience 60 Years / 0 Month Lawrence K. Nordell has 60 Years and 0 Month professional experience

    Discussions 304 Lawrence K. Nordell acceded to 304 discussions, Publications 0 Lawrence K. Nordell Nordell released 0 publications

    Know-How Design (1524) Lawrence K. Nordell used this tag 1524 times, Pipe Conveyor (239) Lawrence K. Nordell used this tag 239 times, Chutes (119) Lawrence K. Nordell used this tag 119 times

    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.
    Lawrence Nordell
    Conveyor Dynamics, Inc.

    website, email & phone contacts:
    phone: USA 360-671-2200
    fax: USA 360-671-8450

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