The catenary idler as a means of energy absorption and spillage prevention

CIM Bulletin, Vol. 75, No. 840, 1982

DOUGLAS G. JAY, Marketing Manager, Material Handling Equipment Division, FMC of Canada Limited, Scarborough, Ontario

Transfer points on belt conveyors have long been a source of problems for both designers and users. Conveyors are generally given a low priority in new equipment layout, thus designers are often forced to compromise due to space limitations. Consequently, for this reason as well as for reasons of initial economics, many conveyors are supplied with less than adequate transfer points.Although not intended as a cure-all, a number of existing installations have been modified with the result that spillage has been reduced to a minimum and belt life has been extended. The most striking modification consisted of replacing conventional rigid frame idlers with five-roll catenary idlers.Although catenary idlers can be traced back to the early 1900s in North America, with a patent having been issued in Washington, D.C. as early as May 29, 1907, the practical application of this concept has only recently reached North America. Major installations include applications at St. Lawrence Cement in Oakville and Iron Ore Company of Canada in Sept-lies, as well as belt conveyors at Stelco's Nan-ticoke plant and yard conveyors at Syncrude in Alberta. These installations were part of major capital expenditures for new facilities and included complete conveyor systems.However, this article will discuss the use of catenary idlers on existing rigid frame conveyors for the purpose of absorbing the energy of falling lumps, protecting conveyor belts and reducing spillage. We will deal specifically with an installation at Inco Metals Company in Sudbury, Ontario, where approximately 40 five-roll catenary idlers were installed on a 42-in.-wide belt convey or handling ore located under the railroad car dumper at the Clarabelle Mill. Before-and-after photographs clearly show the tremendous improvement in the cleanliness of the location, and the savings in maintenance costs and extended belt life have prompted Inco to consider modifying other conveyors.The article will briefly trace the use of catenary idlers as a means of supporting conveyor belts from the original design concept to date.Various illustrations will be used to show how existing conveyors, where spillage and reduced belt life are a problem, can be modified. With the permission of Inco, we will attempt to quantify in specific terms the savings which resulted.
Keywords: Material handling, Equipment, Catenary idlers, Conveyors, Belt conveyors, Spillage prevention, Energy absorption.