744,295. Rotary unbalance compensation. AVERY, Ltd., W. & T. (Schenck Maschinenfabrik Ges., C.). Jan. 20, 1953 [Jan. 23, 1952], No. 1822/52. Class 40(1) [Also in Group XXII] A machine for compensating for rotary unbalance comprises (a) two sets of bearings for accommodating a rotor in two positions, (b) means for transferring a rotor from one position to the other without rotating it, (c) means for rotating the rotor in one of its positions and analysing its unbalance components in two planes perpendicular to its axis of rotation, (d) means for transmitting electrical impulses in accordance with a desired unbalance correction and (e) machining means adapted to operate on the rotor in its second position and controlled in accordance with the said electrical pulses. As shown in the schematic Fig. 1. a rotor 1 resiliently mounted in bearings 2, 3 is driven by a motor 7 and moving coil pickups 8, 9 translate the unbalance oscillations into electrical oscillations. A phase adjustable oscillation generator 14 rotating in synchronism with the rotor 1 produces two outputs having 90 degree phase difference. These outputs may be fed in combinations, determined by the position of the switch 12, of one from the generator 14 and one from either of the pick-ups 8 and 9, to the wattmeter 13 which thus is enabled to read the horizontal or vertical unbalance components at either end of the rotor. With the switch 19 in its upper position, the operator presses buttons to register the respective indicated unbalances together with their sense (i.e. + or -) on registers 17a ... d. When any drilling; operation which may be in process on rotor 1<SP>1</SP> is completed and the unbalances of the rotor 1 are registered, the motor rotor 1 is stopped and then brought to its reference position (in the position determining the co-ordinates corresponding to the measured unbalances). The crankshaft 135 is then rotated by manually controlled motor means (not shown), to effect the interchange of the rotors 1 and 1<SP>1</SP> (for details of mechanism (see Group XXII)), which interchange is effected without rotating the rotors. Simultaneously a switch 19 is operated connecting the storers 17a ... d to the drilling control apparatus and connecting the push-button device , 18 to an alternative set of storers 37a ... d. Unbalance measurements can then be made on a further rotor (or the recently drilled one if a check is necessary), whilst drilling operations are effected on rotor 1. The storers 17a ... d are arranged to store a number complementary with respect to 40 (assuming this is the largest unbalance measurement catered for). The motor 38 is then rotated being automatically stopped at any of the four positions in which a drilling operation is to be performed by one or both of drills 33 -34 on the rotor to compensate for the measured unbalance. The drills are arranged to transmit impulses to the storers in accordance with the depth to which they penetrate and are arranged to be stopped when the storers are counted out. i.e. when the requisite amount of material has been drilled out. Detailed circuitry, Figs. 2 and 4. When the circuit is in operation the switches 59 . . . 59<SP>111</SP> are closed. The banks 71 ... 74 of the switch 52 are arranged to be engaged successively by their respective wipers, the banks being successive 90 degrees arcs so that when the switch starting from its-home position 70, has traversed all four arcs it is again at its home position. When push buttons. e.g. the "30" button 55 and the "5" button 54 are depressed they lock mechanically and open the circuit of a normally operated relay 51, to cause the switch to stop until a circuit is again completed for relay 51 over the wiper 77 of bank 74 masked by the tens button and the fifth contact of bank marked by the units digit. The release of 51 energizes magnet 53 which holds the mechanical locking means 85 for the buttons. During the stopping of the switch relay 88 is operated to enable the switch interrupter contacts 89 to transmit a corresponding number of impulses over switch 16a and one of wires a ... d to the 40 point rotary switches or storers 17a d. Fig. 4. When the impulse sending is complete relay 51 releases the locking means for the buttons, which in turn release relay 88 to prevent the transmission of further impulses. Release of the buttons again releases relay 51 and the switch 52 homes. Depression of the "Plus" or "Minus" buttons 56 brings up relays such as 91m or 91p of which there are one for each position of the switch 16b, these relays locking in circuits which illuminate corresponding lamps 24, 25. If. with the rotor in a particular position e.g. as indicated by the position of the switch 30, the left hand drill is to operate (i.e. the correction for a "plus" measurement is to be made), then relay LP is operated over switch arm 30a contacts of 91p and contact 90c which is made when switch 17a is off-normal. The switch 30 also prepares a circuit for carrying impulses from the transmitter 209 (see Group XXII) associated with the drill, to the appropriate storer 17a. This circuit is completed by a contact 231, made when the driil comes into contact with the rotor. Relay LP operates C<SP>1</SP> which completes a circuit for coil B controlling the drill which proceeds to bore until the impulses transmitted thereby have stepped the switch 17a home whereupon LP releases to stop the drilling. ; Drilling in the right hand plane proceeds if necessary under control of relay RP. When both LP and RP are released the motor turns the work piece and with it the switch 30 until one or both of relays LP and RP operate indicating that a further drilling operation is to take place and so on.