GB174154A - Improvements in and relating to vibration damping devices for elastic fluid turbines - Google Patents

Abstract

174,154. British Thomson - Houston Co,. Ltd., (General Electric Co.). Oct. 14, 1920. Dash-pots and fluid-friction vibration-dampers. -For damping the axial vibrations of turbine shafts, a thrust-absorbing member capable of axial movement is rigidly connected with the movable member of a dash-pot which is adapted to check quick motions but does not seriously interfere with slow motions, the thrust bearing and the dash-pot being so arranged relatively to one another that the lubricant of the thrust bearing cannot enter the dash-pot. The turbine shaft 7 is connected to a thrust disc 15 which, together with the bearing discs 19, is located within an axially movable thrust casing 11, 14 having trunnions connected by rods (not shown), with a yoke 27. This yoke engages the rod 31 of the piston 32 of a mercury dash-pot, which allows a slow transfer of mercury from one side of the piston to the other through the clearance between piston and cylinder. Mercury forced past the U-shaped packing 33 enters a chamber 37 in the head 30 of the dash-pot and flows upwards to a reservoir 40 which is open to the atmosphere and communicates with opposite sides of the piston 32 through pairs of inwardly opening valves 45. Should any mercury leak past the stuffing-box 34 it is caught in a container 43. The oil for the two sides of the thrust disc 15 is fed by a pipe 20 and discharged by a pipe 22, the duct 23 through which part of the oil escapes being arranged above the shaft and its bearing 17 to ensure a permanent supply of lubricant to the latter. The oil and mercury systems unite to restrict the axial movements of the shaft 7, but are maintained entirely separate. Specification 19169/12 is referred to.