GB595906A - Improvements in apparatus for testing want of balance in rotating masses - Google Patents

Abstract

595,906. Testing balance of rotating masses. SELF-PRIMING PUMP & ENGINEERING CO., Ltd., and WATSON, F. J. July 6, 1945, No. 17346. [Class 106 (ii)] [Also in Group XXXVIII] Apparatus for testing unbalance in a rotating mass comprises an electrical pick-up in which current is generated in response to mechanical oscillations of the mass, a cathode-ray oscillograph to which the pick-up is coupled, a sinewave generator in the form of an alternator driven with the mass and electrically coupled to the oscillograph, means associated with the alternator for varying the phase difference of its current and the current from the pick-up, and means operable for varying the value of the alternator current. The test piece 1 is driven by a motor 2, and vertical oscillations due to want of balance actuate two electrical pick-ups 3, 4 in circuit with a valve amplifier 6 and one primary winding 7 of a transformer. The secondary winding 9 of the transformer is connected to a cathode-ray oscillograph 10 where the vertical oscillations produce an approximate sine-curve on the screen. A double switch 5 enables either of the pick-ups to be coupled to the amplifier. The other primary 8 of the transformer is coupled to an alternator 20, also driven by the motor 2, the stator of the alternator being adjustable by a hand-control co-operating with a scale means. The current from the alternator is controlled by a potentiometer 21 or a variable transformer. The arrangement is such that by adjustment of the stator and potentiometer 21 the phase and current of the alternator 20 can neutralize the effect of the pick-up current to produce an approximately straight line on the oscillograph screen. If the stator control is graduated in degrees and the potentiometer calibrated in weight, the amount and position of the weight to be added to the test piece 1 will be given. Specifications 401,569, 498,899 and 549,548 are referred to.