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Modern electric elevators and elevator problems
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CURRENT TOPICS.
[J. F. I.
Electric Heating and Cooking. P . W . GUMAER. (Scientific American, vol. cxiii, No. 23, December 4, I915.)--A new type of heat-
ing unit has recently been devised for electric-heating devices. The high-resistance wire through which the electric current flows is enclosed in a steel sheath, and insulated therefrom by a material which will withstand excessively high temperatures without deterioration. The core wire and powdered insulation are inserted in the sheath when .the three are large in diameter. They are then rolled and swaged to the proper size. By an ingenious arrangement the ends or terminals of the unit are left large in diameter. This facilitates the attachment of terminal connections and permits the terminal to operate at a low temperature. The outside metal sheath protects the core wire from oxidation when operated at high temperatures, as air can not penetrate through the sheath and as the core wire is large in cross-section and comparatively cool where it is exposed to the air. This type of heating unit lends itself readily to the construction of a hot-plate or stove which is practically ideal. The sheathed wire is arranged in a flat coil and molten iron is cast around it. The result is a heating unit which is rugged and durable as an old-fashioned stove-lid. Good thermal contact is obtained from the resistance wire through the sheath to the cast iron. The low thermal resistance path for the heat and a heat-insulating pad beneath the unit secure an especially high efficiency. Modern Electric Elevators and Elevator Problems. QUIST.
D. LIND-
(Proceedings American Society of Mechanical Engineers,
New York, December 7th to Ioth, I915.)--The elevator art has gone through quite a number of more or less radical changes in the last fifteen years. These changes have been partly due to developments in building construction, making it possible and practicable to erect high structures. Elevators may be classified according to the driving power employed : steam-driven, hydraulic, and electric. The first class is now practically obsolete. Hydraulic elevators may be divided into several groups, depending upon the different methods by which the hydraulic power is applied to the car. The principal and well-known types in common use are the horizontal hydraulic (ropegeared), the vertical hydraulic (rope-geared), and the plunger hydraulic (direct-connected). These were introduced in the order named for high speed in comparatively high buildings. The plunger type practically superseded other types of hydraulic elevators during the period of 19o4 to 19o7 . Now, in turn, the plunger has been almost entirely superseded by the gearless "one to one" type of electric elevator. The electric achievement in the design of a motor capable of operating efficiently at 60 revolutions per minute and less is responsible for this radical design of elevator drive. Incidentally this design affoi'ds unusual opportunities ~or interesting and very efficient methods of braking and control.
CURRENT TOPICS.
[J. F. I.
Electric Heating and Cooking. P . W . GUMAER. (Scientific American, vol. cxiii, No. 23, December 4, I915.)--A new type of heat-
ing unit has recently been devised for electric-heating devices. The high-resistance wire through which the electric current flows is enclosed in a steel sheath, and insulated therefrom by a material which will withstand excessively high temperatures without deterioration. The core wire and powdered insulation are inserted in the sheath when .the three are large in diameter. They are then rolled and swaged to the proper size. By an ingenious arrangement the ends or terminals of the unit are left large in diameter. This facilitates the attachment of terminal connections and permits the terminal to operate at a low temperature. The outside metal sheath protects the core wire from oxidation when operated at high temperatures, as air can not penetrate through the sheath and as the core wire is large in cross-section and comparatively cool where it is exposed to the air. This type of heating unit lends itself readily to the construction of a hot-plate or stove which is practically ideal. The sheathed wire is arranged in a flat coil and molten iron is cast around it. The result is a heating unit which is rugged and durable as an old-fashioned stove-lid. Good thermal contact is obtained from the resistance wire through the sheath to the cast iron. The low thermal resistance path for the heat and a heat-insulating pad beneath the unit secure an especially high efficiency. Modern Electric Elevators and Elevator Problems. QUIST.
D. LIND-
(Proceedings American Society of Mechanical Engineers,
New York, December 7th to Ioth, I915.)--The elevator art has gone through quite a number of more or less radical changes in the last fifteen years. These changes have been partly due to developments in building construction, making it possible and practicable to erect high structures. Elevators may be classified according to the driving power employed : steam-driven, hydraulic, and electric. The first class is now practically obsolete. Hydraulic elevators may be divided into several groups, depending upon the different methods by which the hydraulic power is applied to the car. The principal and well-known types in common use are the horizontal hydraulic (ropegeared), the vertical hydraulic (rope-geared), and the plunger hydraulic (direct-connected). These were introduced in the order named for high speed in comparatively high buildings. The plunger type practically superseded other types of hydraulic elevators during the period of 19o4 to 19o7 . Now, in turn, the plunger has been almost entirely superseded by the gearless "one to one" type of electric elevator. The electric achievement in the design of a motor capable of operating efficiently at 60 revolutions per minute and less is responsible for this radical design of elevator drive. Incidentally this design affoi'ds unusual opportunities ~or interesting and very efficient methods of braking and control.