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(b-1a2-9)
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The huge reduction gearing for the freight elevator in this Welsh
textile mill was last in the long line of mill equipment to be
driven. Note twisted belt that allows belt shifting and reversing
of the freight car's motion. The second hoist rope in the car
crosshead leads to a substantial counterweight. (T. Thomas &
Sons)
(Graphic Source: Elevator
World SOURCE 1997-1998)
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(b-1b1-15)
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The earliest steam engine to be located
within a few feet of the bedplate had a 3-foot diameter pulley
on the crankshaft. Belting led a few feet away to the drive machine
the worm shaft of which was extended to hold a 16-inch pulley. No need existed for a belt-shifter for the link-motion-reversing gear on the engine could control the direction of the
car. No brake was used as the worms of that period, and for some
time thereafter, were single thread wherein the thread pitch did
not exceed 12 degrees. The load would unlikely start from a state
of rest as it would necessarily drive the engine to do so.
(Graphic Source: Elevators by Jallings)
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(b-1a1-12a)
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In 1879, the Philadelphia U.S. Engineer's
office requested bids upon a steam-driven elevator that would
lift four tons at 50 fpm. It was to be used in both the construction
and the passenger lifting phases of the Washington Monument construction
in the nation's capitol.
Of the four bids received, Otis's of $18,350 was accepted for a
machine that would operated upon 80 pounds of steam pressure.
Otis also quoted the sum of $2,700 for the conversion to passenger
use, adding "the necessary safety devices, a cab with cane
settee and an oil stove!" The engineers commented that, "A
large drip pan was placed under the overhead pulleys to prevent
oil dripping on the car; and the wire ropes were given a coating
of lamp-black and boiled oil." (Courtesy Otis)
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(b-1a1-12b)
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(b-1b2-14)
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The
Chicago Exhibition of 1898 was a double celebration; the city's 60th
birthday and its recovery from the devastating fire of 1871. Destruction
of almost an entire downtown area allowed the nature and spirit
of rebuilding that sparked major high-rise building design and construction
techniques, including a new generation of elevator engines. Combining
the steam engine with the reduction spur gearing on a common bedplate
led to a proliferation of heavy-duty drum machines with both slack
belt and slack hoist cable switches. These production packages were
created by Eaton & Prince Company of Chicago (Figure 1) and Otis
(Figure 2) at the turn of the
century. |
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(b-1b2-6)
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(b-1b2-2)
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Note the flyball governor affixed to Otis's
penthouse apparatus as an overspeed governor. Overspeeding of
the car flung out the balls, engaging gears that activated a band
brake upon the idler drum rim, effectively stopping the car. No
doubt the large diameter drum was required to provide a suitable
grip for the brake band.
By 1893, Otis had developed a
production steam engine package with heavy slack belt roller to
a shut-down switch and a shut-off
through the control cable to a valve at the steam line feeding
the pistons. Note the twin hoist ropes spooling from the edges
of the drums to the center, assuring a better equalization of
the ropes and lessening the chance of cable overlap. The large
diameter drum in the penthouse is shown at left.
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(b-1b2)
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Almost all steam engine/gearing packages were placed adjacent to
the shaftway as was this of the J.W Reedy. Note the notched iron
ratchet strips set in the wooden guide rails. Should the wagon leaf
crosshead safety be set by slack ropes it was hoped that the load
would be sustained upon the guides. |
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(b-1b2-1)
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Otis's Patent Steam Engine package was
very compact and although one end of the winding drum rested upon
a pedestal, all could very well have been combined upon one bedplate.
(Courtesy Otis)
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(b-1b2-4)
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In the 1870s, compact steam engines were
built by Otis and Crane using an extended bedplate for the worm
gear which extended into a double crank shaft and a heavy flywheel
that smoothed out the motion of the engine, particularly at low
speed. With a larger drum and increased sizing of the steam ports,
the usual speed of 100 feet per minute could be increased to that
of the spur gear type - 200 fpm.
(Graphic Source: Elevators by Jallings)
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