GB725807A - Display indicator - Google Patents

Abstract

725,807. Electric selective signalling system. WESTINGHOUSE AIR BRAKE CO. Jan. 23, 1953 [Jan. 24, 1952], No. 2064/53. Class 40 (1). An electro-mechanical display indicator is operable to any one of an integral number of positions by an electric motor which drives two sprocket wheels of slightly different size geared to a belt containing the indications, wherein electrical contact fingers can be connected in various combinations by arcuate wipers driven by each sprocket wheel and are associated with the motor energizing circuit so that for each combination of positive or zero potential applied to the contact fingers the motor will be energized to drive the sprocket wheels into only one possible unenergized, rest position. As shown, two sprocket wheels 10, 11 (Fig. 1A) carry a notched belt 12 whose surface is divided into twelve symbol spaces of equal length, one of which is visible through a window in the housing. The circumference of wheel 10 is equal to three symbol spaces, and that of wheel 11 is equal to four symbol spaces. The wheel 10 is driven by a motor 14, and wheel 11 carries on its shaft a cam 16 and spring biased roller 17 to maintain alignment between a selected symbol and the window. Each wheel carries circuit controllers comprising an outer ring 18, 19 associated with brushes 20, 21 connected to one terminal of the motor 14, arcuate wipers 22, 23 associated with fingers 24, 25 connected to the other side of the motor via a battery and switch S, and two fingers connected via leads A, B, C, D to the contacts of four relays AR-DR, so that the energization circuit of the motor is dependent on the condition of the relays and the position of the wipers 22, 23. Thus each combination of selective energization of the relays causes the motor 14 to drive the wheels 10, 11 and belt 12 to the one only position in which the motor energization circuit is broken. Thus the indicated symbol is selected by a four element binary code signal applied to the relays AR-DR. In the position where the motor circuit is open the leads are indicated symbols, and by connecting the leads to further control terminals the indicator may be used as a transmitter.