Patent GB-714995-A (GB)
Title: Remote control systems
IPC: G05D3/12
Filed: 1952-10-17
Abstract: 714,995. Electric selective signalling systems. BENDIX AVIATION CORPORATION. Oct. 17, 1952 [Oct. 24, 1951], No. 26167/52. Class 40 (1). Apparatus for the remote control of the position of each of a plurality of shafts by means of 5-element binary code signals transmitted through a pair of wires, comprises means whereby each shaft is associated with switches actuated in accordance with the position of the shaft and inter-connected by a plurality of parallel paths, and the coded signals actuate a series of two-position switches which selectively interrupt the parallel paths so that at the end of a 5-element code signal a motor is energised to drive the shaft to be positioned until detent means operate to stop the shaft at a position unique for each code signal. The apparatus comprises a ratchet-driven shaft 65, Figs. 1 and 3, carrying two cam discs 63, 68 with a stationary disc 67 between them on which is circumferentially located fifteen two-position switches 27-31, 39-43, 46-50. The shafts 1, 2, 3, Fig. 2, to be positioned each carry two wafer switches 19, 20, 37, 38, 44, 45, each having five contacts on the outer, stationary plate, inter-connected with the two-position switches on disc 67 by parallel paths as shown. The shafts 1, 2, 3 can be rotated by a motor 4 through friction clutches 16, 17, 18, an indented disc 7, 8, 9 carrying dial markings on each shaft holding the shaft by means of an arm which is locatable in an indent, except when removed by the energisation of a solenoid 10, 11, 12. In the normal state, a relay 89, energised by the plate current of a double triode value 91, opens the motor energisation circuit at contacts 61, 53. The input pulses, comprising three sets of 5-element combinations of marks and spaces, are applied to terminals 95, 96 so that solenoid 72, mounted on disc 63, is energised by the mark pulses, and solenoid 73 on disc 65 is energised by the space pulses. Each pulse also causes energisation of a relay coil 82 which allows the ratchet wheel 66 to step the shaft 65 at the end of each pulse. The pulses are also fed to the grid of the first section of valve 91, whereupon an increased negative bias is fed to the second section of this valve so that its anode current falls, and relay 89 releases to prepare the motor energising' circuit at contacts 61, 53. At the end of fifteen pulses the cam 63 closes switch 59, whereupon the motor 4 drives the shafts 1, 2, 3 to rotate the wafer switches 19, 20, &c., into the position corresponding to the code on its two-position switches 27-31, whereupon the circuit through relay 10 is opened and the indented wheel 7 prevents the shaft from further rotation. Five seconds after the fifteen pulses have ceased, the bias on valve 91, retained by the charge on condenser 93, has leaked away, and switch contact 61 operates to move the ratchet wheel 66 one more step via switch 85 to bring the system back to normal. In a modification, Figs. 5, 6, the two-position switches are replaced by relays 117-121 selectively energised by the incoming mark signals at terminal 137 acting via rotary wafer switches 109-113, stepped by a similar ratchet device. The relay settings are maintained by holding circuits which are broken when each shaft 1, 2, 3 reaches its correct position. The motor 4 is here energised at the end of each 5- element code signal. A slow acting relay 145 ensures that the rotary switches 109-113 are stepped five times after the first signal element is received in the event of the complete signal being interrupted.