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A portion of a machine's energy was always lost in the transfer of power to that being lifted, whether by belt, chain or hydraulic fluid. Friction was the foe! In the Gallery on "Belt Drives," we saw how these connectors were made ever shorter in the continuing thrust to develop a "package" of the power source and drive. The screw was an option to the leather or chain belt, but the loss of energy remained. An exceptional amount of roping also ate up energy. Lifting engineers knew the answer lay in a direct connection between the power source and the drive sheave even though friction between worm and gear would remain a problem. For many years, the more compact direct-connected drum machine was seen as an answer even though its faults were many. When the direct-connected traction drive was perfected, slippage replaced the inefficiency of poor rope leads and excessive roping and higher rises became possible. The answer was the compact gearless machine with the slow rotation motor within the drive sheave, a traction drive that allowed delicate control of the car at high speed with a lesser amount of machine maintenance. In the "Human Interest" Gallery, Dr. Joris Schroeder discusses the nature of the delays in perfecting the gearless machine package and its accessories. When this most compact of drive units did arrive, the building of higher and more efficient skyscrapers was possible. |
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