GB222195A - Improvements relating to apparatus for testing the balance of machinery having rotating parts - Google Patents

Abstract

222,195. Elverson, A. J. H., and Kennedy & Co., Ltd., H. June 25, 1923. Testing balance of rotary apparatus.-Comprises a method and apparatus involving the use of a stroboscope. The machine A, for instance a motor car engine, is mounted in a frame B in a manner similar to that in which it is mounted in the car frame, the frame B being pivoted at d to a bed plate C between which and the frame is a spring D. The shaft E of the machine drives a parallel shaft F through the medium of a toothed wheel E<1> and a long pinion F' helically splined to the shaft F. This shaft drives a parallel shaft G, upon which is an adjustable out-of-balance mass system H. The system H comprises unequal weights carried by pairs of links of different lengths so that in one position they are balanced. With the system H adjusted in this position, the machine is run up to the critical speed, and the vibrations are viewed by the following means. A stroboscopic flash-timing apparatus s is mounted on the shaft E, and electric leads T', T<2> taken off to a lamp L, an index on which, for instance a cross, is thus illuminated synchronously or nearly so with the machine. An image of this index in the mirror M is viewed through the telescope T provided with a reticulate'd cross-bar system. The masses are then adjusted radially by moving the collar h, and the phase adjusted by sliding the wheel F<1> to bring the vibrations to a minimum. The system H is then moved axially along the shaft G until the position of minimum vibration is reached. From the adjustments made a measure of the degree of lack of balance of the machine can be found. Sometimes the vibrations are due to harmonics caused by out-ofbalance masses on secondary shafts. These may be investigated by driving the disturbing system at the requisite multiple or fraction of the speed of the main shaft, the time flashes being correspondingly adjusted.