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Mono Directional Idler Rollers

Mono Directional Idler Rollers

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Mono Directional Idler Rollers

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  1. Mono Directional Idler Rollers A Brief History: • Original Concept goes back to 1971. • One way Bearings proposed 1990. • Various Institutions “Dabbled” with Ratchets and Snag systems through the1990’s • The inclusion of what might be termed “Mini – Holdback Sprag device” patented by Roller Brake in 2000 • Early installations at Nchwaneng, Target, Boschfontein, Orapa & Growth took off in the PGM Mines.

  2. Mono Directional Idler Rollers • Other technologies developed to compete. • Gruisfontein Arrestor. • Tru Trap Arrestor. • American Belt Brake – An external mechanical Sprag. • The race was on for the best “technology”

  3. Mono Directional Idler Rollers The “Theoreticians” got hold of it - calculating in great detail the number and pattern required to stop a snapped belt. Whilst they differed on number and patterns, they agreed that the “Mono Directional Roller” system is superior to the “Snatch type” system. All tended to agree that a high potential existed for increasing the safety of inclined conveyor systems

  4. Mono Direction Roller Specification • N = Number of units • L = Length along incline • a = Average inclination of conveyor • Si = Pitch of carrying idlers • n = Number of rollers in the Idlers • µ = Drag coefficient • Typical values are as follows • Steel rolls : µ = 0,25 up to about 0,4 • Rubber covered rolls : µ = 0,5 • HDPE rolls : µ = 0,05 (makes you think)

  5. Mono Directional Idler Rollers The “RollerBrake” Company took responsibility, moving from selling “Brake units” to “Safe inclined conveyors”. RollerBrake extended their service to monitoring RollerBrake installations. Some Clients still insist on specifying their own number and installation pattern. Some Engineers also use the technology to back up the original Holdback as originally designed and installed. (With some very interesting results.)

  6. Video: Static Belt Cut- No Load

  7. Video: Static Belt Cut- Loaded

  8. Video: Actual Snap NO Brakes

  9. Video: Actual Snap with Brakes

  10. Field Experience In excess of 1000 Local installations. In excess of 75 foreign, Africa, Europe & Australasia, installations. In excess of 20 reported Belt snaps. Suspect many unreported. ONE “perceived” failure. Investigation revealed that the client had HALVED the specified number! Then there was Aquarius? If YOU were charged with being responsible for an injury caused by a Belt Snap???