Patent GB-374078-A (GB)
Title: Improvements in or relating to indicating devices of the null or zero-indicating type
IPC: G01L7/00
Filed: 1931-01-29
Abstract: 374,078. Relay devices. PAULIN, J. G., 71, K÷pmangatan, Eskilstuna, Sweden. Jan. 29, 1931, No. 2895. Convention date, Jan. 30, 1930. [Class 118 (ii).] Relates to aneroid barometers of the null or zero-indicating type in which the pressure on a diaphragm is balanced by an automatically adjustable force constituted for example by a spring acting between the diaphragm and a nut on a micrometer screw the nut being displaced without turning by the screw, and consists, in addition to the usual tendency and pressure indicating pointers, of the provision of an auxiliary member adapted to indicate rate of change of pressure. On the shaft 1 of the miorometer. screw a wheel 2 is secured having teeth 3 which is shifted tooth by tooth by pawls 4, 41 pivoted at 5, 5<1> on a support 6 pivoted to a frame and adapted to be swung towards the wheel 2. The support is provided with an arm 7 engaging a toothed wheel 8 moving at constant speed and which imparts a periodical reciprocating movement to the support 6. The pawls 4, 41 are normally held in the position shown in Fig. 1 by a spring 9. Between the pawls is an edge 10 urged by a spring to take up the position shown in front of the arms 11, 11<1> extending from the pawls. In front of the edge 10, the point of a tendency pointer 12 connected by suitable gearing to the diaphragm is adapted to move over a fixed plane support 13. The pointer 39 adapted to indicate rate of change of air pressure is connected to a disc 15 free on the shaft 1 and provided opposite the pawls 4, 41 with ten teeth 16 each half the height only of the teeth 3. At diametrically opposite places arranged symmetrically of the device the wheel 15 is provided with teeth 17, 17<1> engaged by locking detents 18, 18<1> on pivots 19, 191, and connected together by a spring. On the shaft 1 is freely mounted a rocking arm 20 which by means of a spring 21 is caused to take up either of the end positions on opposite sides of the plane of symmetry of the device. At the end facing the pawls 14, 14<1>, the arm is provided with a tooth which covers two teeth and a space on the wheels 2, 15 and ends in abutment 23, 23<1> nearly on a level with the ends of teeth 16 and each covering one tooth of the wheel 15. In Fig. 1, the arm 20 is in its right hand position and a stud 241 then holds the detent 18<1> out of engagement. If in the position shown in Fig. 1, the pawls are lowered, the lock 14<1> would penetrate half way into the tooth space and would be prevented by the abutment from engaging the teeth 16. In the position shown, the pointer 12 is slightly to the left of the edge 10 and on movement of the pawls downwards, the pawl 4 is held and the pawl 4<1> engages the wheel 2 with the hook 14<1> turning the wheel 2 one tooth counterclockwise and also moves arm 20 into the left hand position. The stud 24 then releases the detent 18 and stud 24<1> permits engagement of detent 18<1>. The disc 15 meanwhile has not been actuated. If air pressure is unaltered the part 12 is now moved slightly to the right. At the next forward movement of the pawl, the pawl 4<1> will be stopped and the wheel 2 and arm 20 are moved in the opposite direction. to before, the wheel 15 being still unmoved. If the air pressure makes a small change which is maintained, the point 12 is moved say to the right. The hook 14 now functions and moves the wheels 2, 15 one tooth. The member 15 is set stepwise from the middle position by repeated resetting impulses of the same direction, and is restored to mid-position by a spring (not shown) upon change of the resetting direction.