GB629726A - Improvements in indicating devices - Google Patents

Abstract

629,726. Control of two-motors. SAUNDERS-ROE. Ltd., and PIRIE, R. A. Sept. 25, 1947, No. 26036. [Class 38(iii)] [Also in Group XXXIII] A power-operated flying control system with a pair of motors arranged to drive a power shaft though a differential gear is provided with a safety device which remains ineffective so long as the motor shafts rotate in the same direction, but is rendered operative, by rotation of the shafts in opposite directions, to give a warning signal or to stop the failed motor. The invention is shown applied to a control system of the kind described in Specification 619.984, [Group XXXIII], in which a torque shaft 10 is driven through a differential 11 by a pair of hydraulic motors 12, 12a, the latter being driven by variable-delivery pumps 13, 13a, which are operated by continuously running electric motors 14, 14a. The electric motors are controlled by a pilotoperated lever 15 through Selsyn transmitters 18, 18a and receivers 19, 19a. Pinions 42, 42a on the output shafts of the hydraulic motors 12, 12a mesh with pinions 43, 43a having screw thread connections 47, 47a with reciprocating members 44, 44a. Normally, these latter members are held in their neutral positions by pairs of centering springs 46, 46a. Movement of the control lever 15 to initiate operation of the control surface results in closure of one of two switches 50, 50a, and movement of both members 44, 44a in the same direction to close a pair of micro-switches 48, 48a or 49, 49a, the axial movement of the members 44, 44a being limited by the disengagement of the threaded portions 47, 47a. In the event of failure of one of the motors its shaft is rotated in the reverse direction through the differential 11, causing its associated member 44 or 44a to move in the opposite diection to close the previously open switch and the circuit of the appropriate signal lamp 52 or 52a. Instead of, or in addition to the signal lamps, the circuit may include solenoids 54, 54a operating switches 55, 55a controlling the electric motors 14, 14a, so that the motor which fails may be switched off automatically. Additional devices may be provided to indicate unequal motor speeds, the arrangement shown comprising dynamos 26,26a driven by the respective motors, and connected in a bridge circuit with a galvanometer 29 on the pilots' control panel. Alternatively, centrifugal governors may be substituted for the dynamos, the governors controlling variable resistances in a bridge circuit, or switches operating signal lamps, Figs. 3 and 4 (not shown).