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inventor of the "safe elevator"
Elisha Graves Otis was born on a farm near Halifax, Vermont, on August 3, 1811. The youngest of six children, he was always more interested in tinkering with machinery and hanging out at the blacksmith shop than in working on the farm. He made several attempts at establishing businesses in his early years, but chronic poor health and poor business sense kept him from achieving financial success.
In 1845 Otis moved to Albany, New York, where he became a master mechanic in the bedstead factory of O. Tingley & Company. There, over a period of three years, he invented a railway safety brake that could be controlled by the engineer, devices to create rails for four-poster beds, and improved turbine wheels.
Moving to Yonkers, New York, in 1852, Otis was put in charge of organizing and installing machinery for the bedstead firm of Maize & Burns, which was in the process of converting an existing building into a factory. The firm's owner, Josiah Maize, wanted a hoist to lift heavy equipment to upper floors, but all hoists then in use had a critical flaw -- there was nothing to prevent the hoist platform from crashing to the ground if the lifting cable broke (a common occurrence). The mechanism that Otis invented corrected that flaw, and Maize got his heavy equipment hoist.
Otis solved the safety problem by attaching heavy-duty sawtoothed ratchet bars to guard rails on all four sides of the lifting platform and linking the lifting cable to a sturdy spring on top of the lifting platform. In normal operation, tension on the spring kept the ratchet bars from touching the side walls beyond the elevator. If the cable broke, however, the tension on the spring would be released and the ratchet bars would immediately swing out and snap into matching holes alongside the wall, locking the platform firmly in place and keeping it from falling.
drawing of Otis's elevator braking system
The first public demonstration of the Otis Safety Elevator was made at the 1854 Crystal Palace Exposition in New York City. There, crowds watched as Otis himself rode a lifting platform high above the Exposition floor. The crowd gasped when, about halfway up, an assistant cut the lift cable, but was then amazed when the ratchet mechanism kicked in after a fall of less than two inches and kept the platform from falling any farther.
Otis demonstrating his mechanism
Otis and his two sons, Charles and Norton, organized the Union Elevator and General Machine Works Company in 1853, and sold about forty "safety elevators" over the next three years. The company sold, built, and installed the world's first safety elevator for passengers in 1857, in the five-story Haughwout Department Store in New York City. Otis was granted Patent #31,128 for "an Improvement in Hoisting Apparatus Elevator Brake" on January 15, 1861.
Elisa Graves Otis died of diphtheria in Yonkers on April 8, 1861. Charles and Norton Otis reorganized their father's company into Otis Brothers & Co., which is now a wholly-owned subsidiary of United Technologies and the world's leading manufacturer of elevators, escalators, and moving sidewalks.
Library >> Technology >> Mechanical Engineering and Machinery >> Hoisting and Conveying Machinery
This page was last updated on September 28, 2017.