07/26/2012 | Author / Editor: Michael J. Gawinski *, Jason D. Janisch ** / Marcel Dröttboom
Older facilities, such as shipping terminals for ships and barges, which face the risk of high demurrage charges in the event of a ship loading delay, can derive a significant benefit by replacing problem-prone exposed conveyor drive systems with motorized pulleys.
Five major bulk transfer terminals increased conveyor system reliability and improved conveyor belt performance through the use of motorized pulleys. Handling iron ore, coal, and raw salt, these facilities consist of three rail-to-ship fresh water ports, one deep salt mine with barge loaders, and one deep water ship-to-ship and ship-to-rail bulk transfer terminal.
The motorized pulley is an internally-powered and hermetically-sealed conveyor drive system which encloses a motor and gearbox within an oil-filled pulley shell. The special seal and continuous oil bath explain the product’s reliability and longevity.
Built in 1918 as a gravity feed dock, the Duluth Dock, owned and operated by The Canadian National Railway Company (CN), is the most recent North American ship loading facility to upgrade a primary conveyor with motorized pulleys manufactured by Rulmeca.
Two 180 horse power (approx. 135 kilowatt) model 800H motorized pulleys were installed in 2011 at opposite ends of the reversing shuttle belt located atop of the huge ship loader surge bins, see Figs. 1 and 2. They replaced the shuttle’s 30 year old exposed drives, which were part of the conveyor added to the dock in 1981. With winter temperatures as cold as 20 ºF below zero (approx. –30 °C), it is essential that the shuttle conveyor drives be reliable and robust in order to keep ore flowing to dock pockets.
Each of the motorized pulleys operates independent of the other. The east drive is energized to move material eastward and the west drive is energized to move material westward. An enclosed cab is positioned at each end of the shuttle conveyor to provide a clear line of sight to the operator.
For example, when material is transferred west, operator sits in west cab to control shuttle travel and location of articulating boom. This enables the operator to position the shuttle conveyor and the articulating transfer boom conveyor above the north, central, or south ship loader hoppers. Up to 20 ship loader conveyors transfer ore directly from the dock pockets onto Great Lakes ore ships up to 1000 feet (approx. 300 metres) in length.
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