Patent GB-750927-A (GB)
Title: Electric remote control device
Inventor: SHAW HARRY
IPC: G05D3/12
Filed: 1953-10-30
Abstract: 750,927. Electric control systems. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Dec. 31, 1954 [Oct. 30, 1953], No. 30045/53. Class 40(1) In an apparatus for traversing, and positioning an instrument in any selected one of a large number of positions over a range of movement by means of remote control, the instrument is driven by a repeater motor E which is moved in 30 degree steps by a transmitter G. a similar motor F and transmitter H operating a position indicator. Both transmitters are driven by a master motor A which is controlled by a stepping unit B through camoperated switches N1, N2, N3, driven by the motor A. The positive pole of the power supply W is connected to limit switches J opened at opposite ends of the instrument travel and either switch J may be connected to the input of unit B through a manually operated "ADD-SUBTRACT" switch K1. Selector switches K2, K3, mechanically coupled with K1 apply the output of B to either an "ADD" relay unit C or a "SUBTRACT" relay unit D. In the unit B the cam M1 is provided with a notch which operates switch N1 once per revolution and the cam rotates once for every fifty revolutions of the repeater motors. The indicator driven by the motor F registers one unit for every half-revolution of the transmitter, and thus the cam M1 rotates once for every hundred units registered and is termed the "100 step" cam. A "25 step" cam M2, which runs at the same speed as M1 is provided with four notches, and a "5 step" cam M3, which rotates once for every five revolutions of the transmitter, has two narrower notches whereby the switch N3 cannot be operated until one or both switches N1, N2, have been operated in either direction of rotation. A rotary switch L is provided with a "5 step" contact L1 (open circuit), a "25 step" contact L2, a "100 step" contact L3, and a "continuous operation" contact L4. With the switches K in the "ADD" position the positive pole of the supply is connected through K1 to the movable side of the switch N3 and to the arm of switch L, the fixed side of switch N3 being connected through switch K3, and a resistor R1 to the winding C1 of the "ADD" relay, and through closed contacts C2 to one side of the armature of motor A, the other side of the armature being connected to the negative pole through closed contacts C3. The winding C1 is shunted by resistor R2 and is connected to the negative pole through contacts D3 of relay D, the contacts forming an interlock to prevent simultaneous operation of the two relays. A second winding C4 is connected across resistors R1, R2. The switch K2 in the "ADD" position is connected through winding C1 and contacts D3 to the negative pole, and through contacts C2 to the armature of motor A. Similar circuits reverse the polarity to the armature in the "SUBTRACT" position. The motor may be driven slow or fast according to whether it is connected by switch K3 through resistor R1 or S1, or directly to switch K2. Push-button switches P1, P2, by-pass the stepping unit and energize relay C for fast or slow forward speeds respectively and relay D may be similarly energized for reverse speeds by operation of push-button Q1 or Q2. Contacts C5, D5, and C6, D6, energize the field winding of the motor A. To ensure that the full voltage is only applied to the transmitters G, H, when the movement operates, a resistor T is included in the circuit, which is short-circuited by contacts C7, C8, or D7, D8, when the movement operates. Indicator lamps V1, V2, show when the associated limit switch J is opened. The remote instrument may move 100 steps, 25 steps, or 5 steps at a time by selecting the appropriate contact on switch L and momentarily operating the appropriate press-button P1, P2, Q1 or Q2. Single steps may be obtained by placing the switches K in the mid-position and pressing and releasing the slow speed button P2 or Q2 according to direction.