Steam turbines; a practical and theoretical treatise for engineers and students, including a discussion of the gas turbine . ynearly the same pressure on both of its sides. Such a designhas also the advantage of being self-aligning. A helical springshown in the same figure holds the spherical bearing against itsseat in the turbine casing. On the other side of the turbinewheel the shaft passes through a loose-fitting bearing, P, servingprimarily as a gland or stuffing-box to prevent the leakage ofsteam from the casing. The shaft does not pass through thecasing on the right-hand side, so that no
Steam turbines; a practical and theoretical treatise for engineers and students, including a discussion of the gas turbine . ynearly the same pressure on both of its sides. Such a designhas also the advantage of being self-aligning. A helical springshown in the same figure holds the spherical bearing against itsseat in the turbine casing. On the other side of the turbinewheel the shaft passes through a loose-fitting bearing, P, servingprimarily as a gland or stuffing-box to prevent the leakage ofsteam from the casing. The shaft does not pass through thecasing on the right-hand side, so that no precautions are necessaryto prevent leakage of steam on that side. At each side of thepinions of the reduction gearing, the turbine shaft is supportedon plain white-metal (Babbitt) bearings C and CC. The sur- * Critical speed is the name given to that speed of a wheel at which it tendsto rotate about its own center of gravity. In the De Laval turbines a criticalspeed occurs at about i to | of the normal running speed. 184 THE STEAM TURBINE face speed in these bearings is usually designed to be about70 feet per B Oh b PL, C tfI ^ P 5 dIS Speed-reduction Gears. On account of the high speed of theturbine shaft, reduction gears are required to bring the speedwithin practicable limits for utilizing the power. The reduction COMMERCIAL TYPES 185 is usually about ten to one, and is accomplished by means ofsmall pinions on the turbine shaft meshing with steel helicalgear wheels. The teeth of the pinions are very small and arecut directly into an enlarged section of the flexible shaft.* Theteeth for this gearing are cut spirally at an angle of 45 indicated in Fig. 86 the teeth on one side are cut on a right-hand and on the other side on a left-hand spiral. This methodeffectually prevents any movement of the shaft in the directionof the axis and balances the thrust of the gears. Previous tothe time when De Laval demonstrated that gears could be oper-ated at a linear v
Size: 1005px × 2486px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyorkwiley, books
