Results 1 to 4 of 4

Thread: Snub Pulleys in Belt Conveyors

  1. #1
    Axel Witt Guest

    Snub Pulleys in Belt Conveyors

    Snub pulleys are mostly installed in belt conveyors in order to achieve a higher angle of wrap on the drive pulley; in this cases the wrap angle on the snub pulley is in the area of 15° to 30°. At other locations in the belt conveyor pulleys with smaller diameters (similar to the diameter of snub pulleys) are installed to lead the belt into another angle; sometimes these pulleys are called deflection pulleys. These pulleys have wrap angles between 3° and 45°. My question is: does anybody have experiences with negative influences of such pulleys installations with regard to the pulley shell (wear or failure) and to the rubber lagging. What is the limitation in surface pressure of the (rubber) lagging? What is the minimum shell thickness of the pulley. I have enough experience in pulleys with wrap angles between 90° and 180° (210°), but I heard that in the area of a few degrees upto 45° different criteria should be considered.
    Looking forward getting any help from the theorectical point of view (calculation), as well as any practical experiences.
    Best regards,

  2. An attempt at a possible cause:
    Excessive wear would tend to indicate some differential speed between shell and belt.
    Relatively small wrap angle coupled with small shell diameter on a pulley with high rotational friction can result in belt 'skidding' over surface of the pulley resulting in accelerated wear.

    Adi Frittella

  3. #3
    Lyle Brown Guest
    Some of the problem, maybe the snub pulleys are in LT areas, where as deflection pulleys may be in HT areas (or maybe not), hence for a given contact area, there would be increased pressure.
    Are both types typically on clean or the dirty side (compare apples, with apples, per se) of the belt?

    Suspect you are aware of mechnical issues associated with relatively small angles of wrap: (look under shell) (scroll through, see words from Nordell)


  4. #4
    Lawrence K. Nordell

    Lawrence K. Nordell

    President and CEO

    Conveyor Dynamics Inc.

    Conveyor Dynamics Inc.

    Professional Experience 58 Years / 10 Month Lawrence K. Nordell has 58 Years and 10 Month professional experience

    Discussions 2608 Lawrence K. Nordell acceded to 2608 discussions, Articles 0 Lawrence K. Nordell wrote 0 articles, Publications 0 Lawrence K. Nordell Nordell released 0 publications

    Searching nothing specified

    Know-How Design (1521) Lawrence K. Nordell used this tag 1521 times, Pipe Conveyor (238) Lawrence K. Nordell used this tag 238 times, Chutes (119) Lawrence K. Nordell used this tag 119 times

    Axel, I thought you read the forum points on pulleys?

    Any triaxial stress analysis program (Prestress v3.0; ANSYS, et al) will tell you that the arc angle can cause varying degrees of buckling stress when the shell contact angle is in the 60 degree neighborhood verses 180 wrap. Below 20 degrees it again becomes less critical.

    Lyle's second reference leads to some earlier corrections of the hoop stress sensitivity by degrees of wrap. This is a so-so substitute for a proper analysis.

    Make-em fat and sassy, the iron ore industry will love you.

    Contact stress vs pulley diameter is another matter. Now you get into twist wind-up on wires et al.

    Since contact pressure or normal force is proportional to Fn = Tension/Radius, you can do the sums with respect to any reduction in diameter that will not exceed your shell theory of the moment.
    Lawrence Nordell
    Conveyor Dynamics, Inc.

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

Similar Threads

  1. Rulmeca Belt Conveyor Pulleys
    By Denis Zucchinelli in forum Belt Conveyor Pulleys
    Replies: 1
    Last Post: 15th October 2010, 12:31
  2. When to Use Snub Pulleys?
    By Andrés in forum Trough Belt Conveying
    Replies: 4
    Last Post: 3rd October 2007, 15:03
  3. Pulleys for Belt Conveyors
    By Axel Witt in forum Company News
    Replies: 0
    Last Post: 25th August 2005, 14:31
  4. Motorized Pulleys for Belt Conveyors by RULMECA
    By Author in forum Company News
    Replies: 0
    Last Post: 2nd July 2004, 17:45
  5. Conveyor Belt Ice Build-up on Pulleys
    By Trentaiken in forum Trough Belt Conveying
    Replies: 3
    Last Post: 17th January 2004, 15:24

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Single Sign On provided by vBSSO