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Hydraulic Elevator
1 2017-12-19T20:03:00-08:00 Ray Li d76adcdbc48db5fec180c24315aed43f8b9d5f75 14634 1 Courtesy of Prime Kelwin Elevators plain 2017-12-19T20:03:00-08:00 Ray Li d76adcdbc48db5fec180c24315aed43f8b9d5f75This page is referenced by:
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Types of Elevators
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By Ray Li
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2017-12-19T20:09:57-08:00
The first elevators to be installed in buildings were powered by steam engines. These elevators were complicated in their construction, containing multitudes of “bearings, boxes, belts, shafts, wheels, connections, and etc…”[1] Not only were these systems expensive to operate, needing large amounts of coal to power the boilers, but they also required “constant attention to the lubricating parts by an expert engineer.”10 While these elevators made upper floors more desirable, their “operation was too slow” to cause a noticeable “increase in the height of buildings.”[2] The steam powered elevator installed in the Haughtwhat & Company department store ran at a speed of forty feet a minute.[3]
In 1878, Cyrus Baldwin invented the vertical cylinder hydraulic elevator. It was first installed in the Boreel Building and became the standard for years to come.11 Two variations of the hydraulic system emerged. The geared hydraulic elevator used “steam-driven pumps to force water to activate pistons positioned in cylinders vertically in the shaft.”12 The car was attached to the piston through a pulley system and the assembly was located to the side of the car. The pulley “multiplied the stroke of the piston”, allowing the car to travel twice the distance that the piston moved.13 These were used in buildings with heights of several hundred feet and could travel as fast as 200 feet a minute. The second type, the direct plunger, used a car that “sat directly on a piston in a vertical cylinder and was activated when an influx of water drove the car up; water was released so the car could descend.”12 Direct plunger systems were rarely used in buildings taller than ten stories as the cylinder had to “extend into the ground to a depth equal to the height that the elevator rose.”12 The water used by the pistons was stored in large tanks in both variations. The process involved the “use of the water over and over again”, reducing the cost for operating elevators.[4]
The next breakthrough in elevator design occurred in 1890 with the advent of the electric traction elevator. In this system, a set of steel driving cables was used to move the elevator car. One end of the driving cables was attached to the car while the other end was attached to a counterweight to offset the weight of the load. The steel cables were passed over a sheave – wheel with grooves – that was then connected to a gearbox and electric motor. The motor controlled the direction that the wheel turned, either raising the car or lowering the car.[5] The main advantage of this new system was that it “consumed power only in proportion to the load” and since the power was obtained from central power stations, “there was no expense when the motor was idle.”[6] The hydraulic system, on the other hand, required the same amount of power regardless of the load. This was due to the fact that “the water [was] pumped at a fixed pressure and the same volume of water [was] used for a trip irrespective of the load carried by the car.”15 Hydraulic elevators also required the addition of a pumping station within the building which had “standby losses even when the elevator car was not in operation.”15 Geared traction elevators were considerably faster than their hydraulic counterparts, traveling at speeds up to 500 feet a minute.[7][1] OTIS BROS, &. C. O. (1883). ABOUT ELEVATORS.--HYDRAULIC VERSUS STEAM POWER. The American Architect and Building News (1876-1908), 14(393), 1.[2] PASSENGER ELEVATORS.1--I. (1904). The American Architect and Building News (1876-1908), 86(1507), 51.[3] Ross, W. “THE RISE-BUT RARELY THE FALL-OF the elevator”. The Washington Post (Pre-1997 Fulltext), Mar 21, 1995.[4] OTIS BROS, &. C. O. (1883). ABOUT ELEVATORS.--HYDRAULIC VERSUS STEAM POWER. The American Architect and Building News (1876-1908), 14(393), 1.[5] Passenger elevators--IV. (1904). The American Architect and Building News (1876-1908), 86(1511), 83.[6] H, D. JAMES. "VERTICAL TRANSPORTATION." The American Architect and the Architectural Review (1921-1924) 125, no. 2445 (May 07, 1924): 451.
