Patent GB-265247-A (GB)
Title: Improved relay indicating and recording apparatus for measuring instruments
IPC: G01L11/00
Filed: 1925-08-05
Abstract: 265,247. Paulin, J. G. Aug. 5, 1925. Barometers.-Comprises a flexible vacuum chamber acted upon by a counter-spring the tension on which may be varied by means of a resetting mechanism under control of a zero-setting member connected to the chamber through the medium of an amplifying movement transmitting device, characterized by the zero-setting member being yieldingly suspended by bands and threads forming an amplifying device, while the resetting mechanism operates intermittently at constant mtervals to adjust the counter-spring. An evacuated diaphragm case 1 is acted upon by a spring 2 secured at one end 3 to the case, the other end being secured to a nut 4 on a micrometer screw 5 secured to a spur wheel 6. Rotation of the nut is prevented by a forked arm 9 engaging a vertical bar 10. The armature 23 of the driving electromagnet 22 is arranged to adjust the tension of the spring 2 by a reversible gearing 16, 17, 18, bevel gears 20, 21, pinion 19, and spur wheel 6. This gear is operated by ratchet wheel 35 or 36 secured to the shafts of the spur wheels 16, 17, and a double pawl 37 provided on a longitudinal displaceable elastic arm 38 carried at one end by a plate spring 39, while the other end passes through a slot in the armature 23 and is provided with a head. The double pawl may be shifted into connection with the wheel 35 or 36 by a polarized relay 41, the steel armature 42 of which forms part of the arm 38. The relay is controlled electrically by a zero-setting member 11 consisting of a contact arm adapted to make contact with either of two contact plates 43, 44 so that the circuit will be in one direction or the other through the coils of the relay 41. The member 11 normally moves freely clear of the contacts 43, 44 under the influence of the diaphragm. At certain intervals, an armature 46 of an electromagnet 47 strikes the member 11 to make contact with one of the two contacts. The member 11 is carried by a shaft 48 suspended between extensions 50, 51 of the frame by springs 52, 53 tending to turn the shaft in one direction. Secured to the shaft is a transverse pin 54 connected by wires or tapes 55, 56 to other wires or tapes 57, 58 fastened at one end to the frame and at the other to arms 61, 62 extending from the diaphragm case 1. The atmospheric pressure is read by means of a pointer 68 secured to the wheel 6 moving over a graduated cylinder 67, or the pointer may be exchanged for a pen and the cylinder arranged to move axially. A modified mechanical driving member for the resetting device is shown in Fig. 4. Secured to the free end of the zero-setting member 69 is a coupling member 70 having teeth 71, 72 adapted to engage the ratchet wheels 35, 36 respectively. A knife arm 73 operates the member 70 at intervals to displace the member bringing one of the teeth 71, 72 into engagement with the corresponding wheel and moving it through one tooth. A conical steel point 74 ensures that the member 70 will be struck on one or the other side. A small permanent magnet 75 prevents the steel point 74 remaining in a position exactly opposite the edge of the arm 73.