Patent GB-745186-A (GB)
Abstract: 745,186. Gyroscopic apparatus. SPERRY GYROSCOPE CO., Ltd. Oct. 1, 1954 [Oct. 5, 1953], No. 27238/53. Class 97 (3). A gyro-vertical of the kind in which a sensitive element, mounted with freedom of angular movement about two horizontal axes, is arranged to be controlled by a gravity-responsive tilt-detector arranged to detect tilt of the sensitive element from a reference position in which a reference line defined by the element is vertical, or lies along the apparent vertical, and to provide tilt signals defining the sense of departure of the reference line from the vertical, or apparent vertical, and in which the tilt signals from the tilt detector are used to control energization of one or more torque-applying devices to effect the control of the gyro vertical, is characterized by the provision of a warning device arranged to be controlled by the tilt signals from the tilt detector and, in response thereto, to provide a warning signal on the occurrence of abnormal values, or abnormal durations, of tilt signals, or an indication by which such occurrence may be recognized. As shown in Fig. 2, the gyro-vertical is erected by means of two rolling globule mercury switches 5 and 6. The switch 5 has a contact 17 connected by a lead 16 to a source of alternating current. Two other contacts 18, 19 are connected to windings 10, 11 respectively of a torque motor, the other winding of which is shown at 12 and is supplied with alternating current through a phase-shifting condenser 15. A current indicating instrument 20 is connected in series with rectifier 22 between earth and the contact 19. Whenever the torque motor is energized, a current passes through the instrument 20, moving its indicating member from one position to another. The switch 6 is similarly associated with the windings 8 of a second torque motor and with a second current indicating instrument 21<SP>1</SP>. The pilot or observer can see, by observing the instruments 20, 21, whether the torque motors are operating properly. In a modification, Fig. 4, the energization of the torque motors is caused to excite the windings 22, 23 of a pair of clutches 27, 28. A second pair of clutches 29, 30 are connected to the other torque motor. All the clutches are driven slowly from a common shaft 35 by means of an electric motor 34. Clutch 22 when energized drives a clutch plate 31 carrying a projection 38 which is normally spring-urged against a stop 40. Prolonged energization of a torque motor causes the pro-. jection 38 to be brought into contact with a switch 41 which is thereby opened. Clutch 28, on the other hand, is constantly engaged but is disengaged when the torque motor is energized, and carries a projection 43 normally spring- urged against a stop 50. When the torque motor is de-energized for a considerable time, the projection 43 is brought into contact with the switch 42 which is thereby opened. The switches 41, 42 are connected in series with switches 411, 421 associated with the second pair of clutches, which are controlled by the second torque motor. All four switches are in series with an indicating instrument 20 and a battery 45. Should any of the switches be opened, a flag 46 on the indicator 20 is brought into a visible position. Thus if the torque motors are either energized or de-energized for an abnormal length of time, the flag 46 will show that the gyroscopic instrument is not working properly. Flag 46 will also be operated if the current supply to the torque motors fails. In a further modification, the rectifiers 22 in Fig. 2 are replaced by a phase discriminating network, so that the indications on the current indicating meters 20, 21<SP>1</SP> depend in direction on the direction of the torque motors.