GB761487A - Improvements in or relating to pressure gauges - Google Patents

Abstract

761,487. Differential pressure gauges. APPLEBY & IRELAND, Ltd. March 8, 1955 [March 8, 1954], No. 6719/54. Class 106 (2). A differential pressure gauge comprises two capsules 18, 19, Fig. 6, having bifurcated lugs 22, 23 on their operating faces in which are pivoted the two ends of a lever 24 having a central knife-edge portion 25 colinear with a line joining the pivots and bearing against an arm 36 secured to a rocking spindle 35 mounted at its ends for movement about its longitudinal axis in ports 31, 32, the spindle 35 being adjustable in position along that axis by screws 33, 34 so that the point of contact of the arm 36 with the knife-edge 25 may be adjusted to the neutral point where no movement occurs when equal pressure is applied to the capsules 18, 19. The operating characteristics of the capsules may be adjusted by screws 72, 73 acting on springs 68, 69 bearing on rounded faces of the lugs 22, 23. The rocking spindle 35 is provided with a lever 37, Fig. 4, pivoted at 44 to a slotted rod 43 engaging with a crosspin 42 on a bifurcated arm 41 of a rockshaft 40. The arm 40 carries a second bifurcated arm 48 connected by a link 49 to an arm 50 supported by a short flat spring attached to the frame of the instrument and a helical spring 45 also attached to the frame is secured to the lever 37 thereby normally keeping the crosspin 42 at the end of the slot in the rod 43 and eliminating back-lash. In the event of excess pressure being applied to the capsule 19 the increasing pressure of the knife-edge 25 on the arm 36 eventually overcomes the light force of the spring 45 and carries the rod 43 away from the pin 42, thereby protecting the mechanism. The rockshaft 40 bears at its lower end a quadrant 53 movable between stops 65 and driving through gears 54, 60, 61 a spindle 62 carrying the pointer. An electric buzzervibrater may be provided to obviate sticking of the indicating mechanism.