A dumbwaiter is a small
freight elevator or lift intended to carry objects rather than people.
Dumbwaiters found within modern structures, including both commercial, public
and private buildings, are often connected between multiple floors. When
installed in restaurants, schools, kindergartens, hospitals, retirement homes
or in private homes, the lifts generally terminate in a kitchen.
The term seems to have been
popularized in the United States in the 1840s, after the model of earlier
"dumbwaiters" now known as serving trays and lazy Susans. The
mechanical dumbwaiter was invented by George W. Cannon, a New York City
inventor. Cannon first filed for the patent of a brake system (US Patent no.
260776) that could be used for a dumbwaiter on January 6, 1883. Cannon later
filed for the patent on the mechanical dumbwaiter (US Patent No. 361268) on
February 17, 1887.Cannon reportedly generated a vast amount of royalties from
the dumbwaiter patents until his death in 1897.
A simple dumbwaiter is a movable
frame in a shaft, dropped by a rope on a pulley, guided by rails; most
dumbwaiters have a shaft, cart, and capacity smaller than those of passenger
elevators, usually 45 to 450 kg (100 to 1000 lbs.) Before electric
motors were added in the 1920s, dumbwaiters were controlled manually by ropes
on pulleys.
Early 20th-century codes
sometimes required fireproof dumbwaiter walls and self-closing fireproof doors
and mention features such as buttons to control movement between floors and
locks on doors preventing them from opening unless the cart is stopped at that
floor. Dumbwaiter Lifts in London were extremely popular in the houses of the
rich and privileged. Maids would use them to deliver laundry to the laundry
room from different rooms in the house. They negated the need to carry handfuls
of dirty washing through the house, saving time and preventing injury.
A legal complaint about a
Manhattan restaurant's dumbwaiter in 1915, which also mentions that food orders
are shouted up and down the shaft, describes its operation and limitations as
follows:
[There is] ... great play between
the cart of the dumb-waiter and the guides on which it runs, with the result
that the running of the cart is accompanied by a loud noise. The rope which
operates the cart of the dumb-waiter runs in a wheel with a very shallow
groove, so that the rope is liable to and does at times slip off. ... The cart
has no shock absorbers at the top, so that when it strikes the top of the shaft
or wheel there is a loud report. ... [T]he ropes of the dumb-waiter strike such
wall at frequent intervals with a loud report. ... [T]he dumb-waiter is often
negligently operated, by running it faster than necessary, and by letting it go
down with a sudden fall.
More recent dumbwaiters can be
more sophisticated, using electric motors, automatic control systems, and
custom freight containers of other kinds of elevators. Recently constructed
book lifts in libraries and mail or other freight transports in office towers
may be larger than many dumbwaiters in public restaurants and private homes,
supporting loads as heavy as 450 kg (990lbs)
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The “Twelfth Five-Year Plan†of the steel industry highlights three highlights
The Ministry of Industry and Information Technology issued the "Twelfth Five-Year Development Plan for the Iron and Steel Industry" on the 7th, which is one of the earliest "12th Five-Year Plan" issued in China's raw materials field, and another industry after the "Steel Industry Adjustment and Revitalization Plan" in 2009. Programmatic document. The “Twelfth Five-Year Plan†points out the path of “from large to strong†in China's steel industry in terms of product quality, energy conservation and emission reduction, and industrial layout. Since the beginning of this year, with the slowdown in the growth rate of China's fixed asset investment, the demand for steel products is of concern. The Plan made a prediction. In 2015, domestic crude steel-oriented consumption was about 750 million tons. This figure means that the average annual growth rate of China's crude steel consumption in the next five years will be only about 4%, which is much lower than the annual growth rate of 12% of crude steel production in the “Eleventh Five-Year Planâ€. While controlling the quantity, the “Planning†puts the quality of the improved products at the top of the six goals and puts forward some specific indicators. For example, the high-strength steel and silicon steel used in automobiles have a market share of over 90%, and the proportion of rebar used in grade 3 and above exceeds 80%. In the view of Li Xinchuang, deputy secretary-general of China Steel Association and president of the Metallurgical Industry Planning Institute, China's steel industry has two major problems: one is that there are too many backward production capacity, and the other is that the layout is unreasonable. Since 2010, the country has made great strides in eliminating backward production capacity, but the layout adjustment has been difficult. The unreasonable layout of the steel industry is simply summarized as “Northern Heavy South†and “East East and Westâ€. The newly released "Planning" has a new saying on this issue. It emphasizes that the Bohai Sea and the Yangtze River Delta region will no longer build new steel bases in principle, but said that it is necessary to speed up the construction of Zhanjiang, Fangchenggang and other southeast coastal steel boutique bases. “The Zhanjiang Steel Plant not only meets local demand, but also facilitates the transportation of raw materials. At present, Australian iron ore takes 7 days to Shanghai and 5 days to Zhanjiang. This time, it can save huge logistics costs.†Baosteel Chairman Xu Lejiang pointed out. Since 2008, China's steel industry has been in a downturn. From the inside, it is affected by overcapacity. From the outside, it is mainly suffering from high-priced iron ore. For this issue, the "plan" will definitely strengthen the construction of the iron ore resource security system. This includes actively optimizing the global allocation of iron ore resources and adding more than 100 million tons of offshore iron ore production capacity. At the same time, accelerate the establishment of a scrap recycling system and encourage enterprises to establish scrap recycling and processing bases overseas.