Otis is the largest global elevator and escalator supplier by revenue with around one quarter of share excluding Japan. In 1854 Otis' founder and namesake, Elisha Graves Otis, invented a safety mechanism that prevented elevators from falling if the hoisting cable failed.The company's product and service lifecycle begins with installations of elevator units in new buildings, later selling maintenance services on the units, and eventually replacement of the units after the average 15-20 year useful life of an elevator. As the largest global OEM, over decades Otis has built a base of 2 million elevators under service. Its business model is much the same as that of its competitors Kone, Schindler, and Thyssenkrupp.