Patent GB-678768-A (GB)
Title: Improvements in or relating to gyro-verticals
IPC: G01C19/44
Filed: 1950-06-16
Abstract: 678,768. Gyroscopic apparatus. SPERRY CORPORATION. June 16, 1950 [June 17, 1949], No. 16080/50. Class 97 (iii). [Also in Group XXXVII] A gyrovertical having gravity responsive erecting means and two pick-off devices 26, 30, has a starting switch arrangement for effecting a sequence of switching operations controlling the power supply for the gyro rotor, the switch arrangement having a " running " position in which energy is supplied for maintaining the spin of the rotor and for enabling the pick-off devices to function as signal providing means, and a " starting " position in which at least one pick-off is differently energized so as to act as a torque motor for rapidly centralising the gyroscope. On closing the four-knife switch 34, a direct current motor 41 is energized, through contact 61 and armature 65 of a relay 57, from a source connected to leads 36 and 40. The motor 41 drives a series of cams on shaft 47 by means of gears 48 and 50, the cams and their respective followers providing a sequential switching system. Switches 10 and 11 are opened to disconnect the three-phase supply 35 from the stator 24 of the gyroscopic rotor spinning means and switch 1 is then closed to by-pass contact 61 and armature 65 of the relay 57. Following this, switches 2, 5 and 7 are closed and 3, 4 and 6 are closed in the right-hand position. Switch 2 allows the energization of the coil 67 of relay 57 and the armatures 65, 64, 63 and 62 being moved against the action of spring 66 enables armature 62 and contact 58 to close a holding circuit for the relay. Following this, switch 2 reopens. On the closing of switches 5 and 7 and the closing in the right-hand position of switches 3, 4 and 6, the rotors 28 and 32 of the pitch and roll pick-offs respectively are energized through leads 82 and 68 from autotransformer 81 connected across two of the alternating supply terminals and the stators 27, 31 are connected through leads 97, 94; 93, 91, respectively, to lead 68 and through leads 92, 90, and lead 88 to a low voltage tapping on transformer 81. Since the rotors 28, 32 are rigid respectively with the horizontal axes of rotation of the gyro rotor frame and the gimbal ring wherein the latter is mounted and the stators 27, 31 are rigid with the gimbal ring and the supporting casing respectively, the pick-offs 26, 30 so energized will act as torque motors for centralising the gyro rotor, to within 15 degrees of its normal position before the rotor starts spinning. After this switches 8 and 9 close and a circuit is completed to the stator 24, of the squirrel-cage type induction motor for spinning the gyro rotor, through transformer 9 which supplies 175 volts for over-energizing the motor. The rotor reaches about 500 r.p.m. and switches 8, 9 reopen, the low rotor speed allowing a greater erection rate than normal of the gravity responsive device which may be as shown in Specification 633,954. Following this, switches 8, 9 reclose, the gyro rotor rapidly reaching its normal operating speed, and then switches 5 and 7 are opened whilst switches 3, 4 and 6 are closed in the left-hand position. This allows the pick-off rotors 28 and 32 to be energized through lead 88 from the low voltage tapping on transformer 81, and the stators 27, 31 to provide signals indicative of pitch and roll in leads 112 and III respectively. Later, switches 8, 9 open and 10, 11 close, the normal 115 volts being thereby applied directly from source 35 to the stator 24. After one rotation of shaft 47, switch 1 opens and motor 41 stops.