Patent GB-170864-A (GB)
Title: Improvements in gyroscopic apparatus
IPC: G01C19/38
Filed: 1921-10-31
Abstract: 170,864. Paxton Gyroscope Corporation, (Assignees of Paxton, C. M.). Oct. 29, 1920, [Convention date]. Gyroscopic apparatus.-The axis of rotation of a gyroscope is maintained in a fixed direction in space in a plane at right-angles to the axis of the earth, the gyroscope being principally intended for an indicator of longitude. Precession due to the earth's rotation is counteracted by the application of an alternating torque about an axis parallel to the axis of the earth so as to set up a precessional oscillation of determined amplitude, the said torque being of very much greater magnitude than that due to the earth's rotation. The gravitationally-balanced gyro-casing 21 is pivoted at 20, 20 in a ring 16 pivoted at, 17, 17 in a frame 1 which in turn is mounted on pivots 2 in a fork 4 capable of rotating on a vertical bearing 9. The fork can be turned in azimuth and the frame 1 turned about the pivots 2 by repeater motors 14, 7 respectively, so as to maintain the pivot axis 2, 2 in an E-W direction and to maintain the axis 17, 17 parallel to that of the earth, the motors being connected to an auxiliary gyroscope the axis of which remains parallel to the earth's axis. The alternating torque above referred to is applied about the axis 17, 17 by the means shown in Figs. 1, 6 and 7. The pivot 17 carries one member 30 of a clutch which can rotate but not slide thereon, a spring 51 being secured at one end to member 30 and at the other end to a, collar 55 secured to the pivot. The other member 31 of the clutch is rotatably and slidably mounted on a fixed spindle 17<a> and is adapted to be operated by electromagnets 32, the armature 33 of which is slidable on the hub of member 31 which it operates through a strong spring 34 on a weaker spring 34<a>. The member 31 carries guide screws 35 on which the armature 33 slides. The arrangement of springs 34, 34<a> is such that energization of the magnets 32 first engages the clutch and afterwards closes contacts 36, 37 to complete the circuit of torqueapplying magnets 38 the armature 39 of which is fastened to the clutch member 31. The stroke of the armature 39 can be adjusted by a screw 41 to vary the torque applied to the pivot 1'7 bythe spring 51. The magnets 38<1> 32<1>, and associated parts shown to the left of Fig. 1 are similar to the magnets 38 &c. but are arranged to apply torque in the opposite direction. The means for energizing the magnets 32, 32<1> alternately consists of a strip 60, Figs. 1 and 5, secured to the precession axis 20 and adapted to make alternate contact with adjustable contact screws 62 as the casing 21 oscillates. The screws 62 are arranged in the circuits of electromagnets 70 which are thus alternately energized to attract a switch 71 moving over contacts 72, 73 included in the circuits of magnets 32<1>, 32 respectively. The frame 1 carries a pointer 25, Fig. 2, to indicate longitude in connection with a graduated dial 22 carried by the ring 16. The torques exerted by the magnets 38, 38<1> are adjusted by means of the screws 41 until the difference between them is equal to the torque due to rotation of the earth. The resultant torques exerted on the pivots 17 are then equal in total value, average value, duration and rate of change. The required adjustment may be determined by comparing the indications of the instrument with those of an accurate chronometer.