. The Röntgen rays in medical work . belt from the motor, and in this way the motor circuit is keptentirely separate from the exciting circuit of the coil. A specialscrew and plunger are used to vary the level of the mercury,and so to vary the depth to which the moving arm is immersed,and the duration of the contacts. THE ELECTRICAL APPARATUS 41 The turbine break (Fig. 22) is a motor-driven interrupter, inwhich mercury is propelled by a centrifugal pump in a continuousstream in a horizontal direction. The mercury jet strikes alter-nately on contacts and on insulating material. Several modifi-c
. The Röntgen rays in medical work . belt from the motor, and in this way the motor circuit is keptentirely separate from the exciting circuit of the coil. A specialscrew and plunger are used to vary the level of the mercury,and so to vary the depth to which the moving arm is immersed,and the duration of the contacts. THE ELECTRICAL APPARATUS 41 The turbine break (Fig. 22) is a motor-driven interrupter, inwhich mercury is propelled by a centrifugal pump in a continuousstream in a horizontal direction. The mercury jet strikes alter-nately on contacts and on insulating material. Several modifi-cations of this interrupter exist. Thus, in some forms themercury jet is stationary, and the interruptions and contactsare made by a deeply-toothed cylinder of metal, which revolvesaround it. In others the jet itself revolves, and in its revo-lutions projects the stream of mercury against a pair of con-ducting armatures, and. so closes the circuit at certain armatures are made in several sizes, to suit the pressures of. Fig. 22.—Turbine Jet Interrupter (K. Sciiall) current to be used, and the duration of each period of closure canbe further controlled by the simple movement of a handle, whichdisplaces one of the armatures. The number of interruptions persecond is regulated by varying the speed of the motor. Withthis interrupter a steady light can be obtained on the screen. Theturbine break will stand heavy work, and may be used for longperiods without attention. The armatures gradually wear away,but they can readily be replaced. In the forms of turbine inter-rupter with fixed jet the duration of the contacts is varied byraising or lowering the revolving toothed cylinder, which has itssegments tapered off below for this purpose. 42 THE RONTGEN RAYS IN MEDICAL WORK These interrupters are to be found, with various modifications,in the catalogues of different instrument-makers. In some formsthe motor is fixed in a vertical position, so as to drive with astraight bel
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