Low Rim Drag Idlers
Improving idler drag is of interest to all engineers and operators who wish to be good environmental sheppards.
We are aware of the attempts to low the rolling resistance with improvements in seals and lubricants. What else do your suppliers advertise that improve rolling resistance within the idlers? ■
Re: Low Rim Drag Idlers
The idler “proper”, resistance arises due to following :
- Bearing frictional resistance. This can arise due to make / type of bearing, shaft deflection, and misalignment tolerance in fitment i.e. how concentric are the two end housings. It also depends how closely the fitment values are achieved under mass production condition. The grease viscosity and temp variation range.
- Roller diameter i.e. bigger the diameter lesser will be the rotation.
- Perpendicularity of the roller axis with the belt motion. This depends upon the quality of idler set (angular misalignment values limitation actually achieved). It also depends on the quality of idler installation. The idler set may be of best quality but if installation is not upto the requirement, the idler will create sliding drag resistance to the belt motion.
- The belt pinching at the gap between rollers. In this respect offset idlers are marginally better than incline type idlers.
I think there are no other issues which will contribute to the resistance by idlers. The readers can add such points if anything is missed.
It is to be noted that belt denting flexure resistance, belt bending flexure resistance, material flexure resistance etc are “external” to the idlers.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Author of Book : Belt Feeder Design and Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: parimul@pn2.vsnl.net.in ■
Idler Drag Notes
Another less known drag condition is the surface texture of the ilder shell. When the belt's cover rubber is deformed by roller indention, the rubber must slip on the roller surface during each indention process. This act does added measurable drag and is dependent on the apparent shell-to-belt contact friction. ■
Low Rim Drag Idlers
Has anyone got any experience with the low rim drag idlers being offered by certain vendors around the world. I won't say anything here about how the lower rim drag is said to be achieved - that might be proprietary information - but for anyone who has looked into them you will know what I am talking about. Happy to have private conversation off-line. ■