Sunday, March 22, 2009

horizontal conveyor-belts

Caption for Figure 5: "Close-up view of tripper."

At the Standard Elevator, Buffalo, New York. Located on the bin floor, the tripper (sometimes called a trimmer) sweeps grain from the horizontal conveyor-belt into the top of a grain bin through a chute. Note the great length of that conveyor-belt. Each of those small circles along the left-hand side is the capped opening to a towering grain silo made of reinforced concrete.

Photographed by Jet Low, 1990.
Courtesy the Library of Congress, Prints & Photographs Division,
Historic American Engineering Record.

From pages 198-199 of American Colossus:

Prior to 1868, when the pioneering Niagara Elevator was built, some grain elevators in Buffalo had horizontal conveyor-belts installed in their “basements,” that is, below their grain bins. Such conveyors brought grain dumped down on them to a boot, from which a lofting leg elevated the grain to the top of structure. It wasn’t strictly necessary to have such a conveyor – the spouts and chutes could simply send their grain directly from the bottoms of the bins to the boot – but this might involve a great tangle of spouts and chutes, if not the need for a second (or third!) lofting leg to accommodate them all.

At the Niagara Elevator, which was designed by George H. Johnston, horizontal conveyor-belts were installed both above and below the grain bins. The walls and foundations of the building were able to accommodate all that weight – the combined weight of the grain bins themselves, their contents, and two floors’ worth of machines – because they were laid down upon newly driven piles, more than a thousand of them, which secured a solid place for the Niagara on the otherwise weak, marshy banks of the Buffalo River. Like the Bennett Elevator before it, the Niagara had a solid masonry foundation and ironclad wooden walls and grain cribs. But unlike the Bennett, it could store 800,000 bushels, not 600,000.

The key feature of the steam-powered conveyor belt that ran alongside the tops of the grain bins was the “trimmer” or “tripper,” a device that deflected the flow of grain off the belt, and down and into a particular grain bin. (See figure 5.) The ingenuity, that is, the usefulness, of the trimmer lay in the fact that it could be unlocked, moved up or down the line, and then locked into position above a different grain bin. This meant that the number of big turn-heads and spouts previously needed to conduct the grain down from the garner and scales in the marine tower to the tops of the bins could now be drastically reduced; the whole procedure could be simplified. Same thing for the basement of the elevator, even though the trimmer didn’t play a part down there: thanks to the steam-powered conveyor belt, the number of spouts and chutes leading down from the bins to the boot of the lofting leg could be reduced. The cramped space of such basements could now be “freed up.” But “freed up” spaces came with a cost: conveyor belts exposed more grain to the air, and thus created more fugitive grain dust than did the spouts, unwieldy though they were.

As a result of the lateral “reach” of the new conveyor-belts, elevator operators and designers began to re-conceptualize the way that grain bins might be organized. Instead of locating the bins close to or even around the spouts that came down from the marine tower – which was a spatial practice that tended to make and keep the elevators’ main houses tall and boxy (sometimes even round) – the designers began to array the bins in long straight rows that led away from the marine tower. This meant that large-scale elevators no longer needed to be centralized like the Watson or oriented along conflicting lines, as in the case of the Bennett Elevator (one line ran from the marine tower at the Evans Slip side of the elevator to the other end of the building, i.e., along the Buffalo River, while another line ran from the boiler room and the primary marine tower to the Buffalo River). New elevators could now be built in a long, narrow and tall row, perpendicularly to the river, which not only “freed up” space along the wharf, but also created space for the railroads to lay down little feeders that led to their trunk lines. These new elevators could not only transship grain from lake to canal, but from lake to rail, as well.

No comments:

Post a Comment