"The beauty of the reducer is that it's so huge," says Dragos Oprescu, a principle applications engineer for Timken who clearly enjoys working with really big mechanical stuff. He's referring to the 40-ton speed reducer on one of the Eiffel Tower's seven elevators, which was installed in 1965 and engineers rebuilt in 2004. The heavy worm gear (36 metric tons), manufactured by the CMD Company, achieves a speed reduction of 13:1 between the intermediate and output shaft operating at 14 rpm. Oprescu was part of a Timken engineering team in Colmar, France, that was responsible for analyzing the six original bearings on the reducer's pulleys and output shaft (they were found to be in excellent operating condition), and specifying new parts. They replaced the 35-inch-diameter tapered bearings with nearly the exact same design, save for material and other design improvements that may help see the new bearings through the next 40 years and beyond. An advantage of the tapered bearing design in this application, says Eric Schumacher, Timken sales engineer, is its capacity to accommodate both axial and radial loads and the avoidance of slipping speeds between the bearing race and its inner ring—resulting in lower energy losses.
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