Patent GB-306057-A (GB)
Title: Improvements relating to systems for repeating electrically the readings of gyroscopic compasses
IPC: G01C19/40
Filed: 1927-11-11
Abstract: 306,057. White, A. E., (Sperry Gyroscope Co.). Nov. 11, 1927. Tell-tale apparatus. - Relates to systems for repeating at a distance fine and coarse readings of a' gyroscopic compass. As shown in Fig. 9, a transmitter T for signalling coarse indications is driven from the follow-up element of the compass through gearing having a 1 : 1 relation so that the transmitter moves through one revolution for each revolution of the master instrument. A transmitter T<1> for signalling fine indications also is driven by the follow-up device through a 36 : 1 ratio gearing. The transmitters operate separate repeater motors M, M<1> coupled to indicators D, D<1> the latter of which rotates through one revolution for each 10‹ rotation of the indicator D. The transmitters and repeaters are of the resultant field type the rotors being supplied from A.C. mains while the polyphase stators are electrically coupled. Instead of an AC. system, a D.C. system of the type described in Specification 15679/11 mav be used. Provision also is made for introducing into the master instrument and the repeaters corrections to compensate for errors arising from the variation of speed, course and latitude. These errors are corrected by adjusting the position of the transmitter stators relatively to the rotors through a sector 33, Figs. 5 and 7 which is geared to pinions 30, 30<1> adapted to rotate the stators. The gearing is such that the corrections introduced into the transmitters T<1>, T are of the same ratio as the relative speeds of the transmitters. Correction in respect of any given latitude is partly made by adjusting the gear 32 relatively to the sector 33 by a screw 34. Variation of course is compensated by automatically controlling the position of the sector 33 from a so-called " cosine ring " provided on the master compass and comprising an eccentric groove 41. The groove transmits its movements through levers 44, 45 to rotate the sector 33 about its pivot 49. The connection between lever 45 and the sector is such that correction for speed and latitude may be introduced. The lever 45 is pivoted within a support 42, Fig. 7, and has longitudinal slideways 47 adapted to accommodate the pivot connection 46 between the lever 45 and the sector 33. The pivot 46 is adjustable bv a nut 50 and the arrangement is such that when the pivots 43, 46 are in alignment no movement of the sector 33 is produced by rotation of the lever 45, but as the pivot 46 is adjusted a leverage arm is set up between the pivots to cause movement of the sector depending upon speed and latitude. The follow-up element of the master compass is given a continuous small oscillatory movement in order to overcome static friction and in order to avoid the transmission of this movement to the repeaters the follow-up device is connected to the transmitters through lost motion devices. Each device comprises a member 63, Fig. 3, which is driven from the follow-up device, and is adapted to co-operate with one or other of the members 64 after a predetermined lost motion. The members 64 are mounted on a casing 65, which is supported on the shaft of the transmitter rotor. The degree of lost motion may be varied by a pinion 67 which engages the threaded periphery 68 of the member 64. Specifications 110,046 and 263,187 also are referred to.