Patent GB-190789-A (GB)
Abstract: 190,789. Roucka, E. Sept. 26, 1921. Indicating. - In a device for obtaining powerful movements proportional to the weak movements of an indicating instrument two members are provided capable of moving in the same direction or one towards the other. The first member is periodically acted on by an auxiliary source of power, or is stationary and acts as a stop when the second member is acted on by the auxiliary power. The second or recording member is connected to indicating &c. apparatus. Between the two members and controlling the extent of movement of the recording member is a member which is moved in accordance with the value it is intended to indicate. At the end of each effect of the auxiliary power the recording member may be held in position by a brake. In an example, Fig. 1, for repeating the readings of a gas analyser, unabsorbed gases from a furnace lift the bell 1 to a varying extent and the recording member 11 and the member 14 perform corresponding movements. At the end of each analysis a float 28 completes at the contacts 29, 30 the circuit of a solenoid 22 which attracts its armature 21 against the action of a spring 15<a> and dashpot 24, 25. The part 16, which is shaped as shown in Fig. 2, is moved to the left and moves the arm 35 a distance which depends on the distance between the part 16 which may be inclined, and the inclined part 38 at the position of the member 14. At the end of the stroke the stop member 18 momentarily disengages the brake 44 from the part 37 of arm 35 to allow the latter if necessary to be forced by the spring 40 to the correct position where it is subsequently held. Movement of the arm 35 may directly indicate or record the value or may be transmitted to an arm 39 to operate distant apparatus electrically as shown, pneumatically or hydraulically. In the form shown the arm 39 also moves the wheel 54 of a counting mechanism 57 across the surface of a constantly driven disc 53. In a modification, Fig. 3, the pointer 64 of an indicating instrument moves between a curved member 70 and a member 84. The member 70 is periodically lifted by the cam 74 and the cam 75 lifts the brake 80 just before the end of the movement of the member 70 the part 84 and the pointer and recorder 90 then assume a position corresponding to that of the pointer 64. The curvature of the part 70 or of the corresponding part 38 shown in Fig. 1 is preferably made variable by means of screwed rods 91<1>, Fig. 6, and nuts 92<1>. In a modification, Fig. 7, the indicator pointer moves between a U-shaped ring 104 which is periodically moved downwards and two rings 108, 109 oppositely inclined to the shaft 113. The movement of the ring 104 causes relative movement between the rings 108, 109 dependent on the position of the pointer 103, and a proportionate movement of the arm 121. The latter acts to admit or release fluid under pressure to or from a chamber 126 communicating with a pressure gauge 130. In a modification of the device shown in Fig. 7, the ring 104 is fixed and the periodical movement is given to the support 131, 132 of the levers carrying the rings 108, 109. The arm 121 instead of carrying the arm 122 is formed with a flat surface at its end against which bears a roller carried by a spring-pressed rod which carries the arm 122.