Patent GB-792417-A (GB)
Title: Improvements relating to instrument assemblies and to diaphragm operated instrumentssuitable for use therein
Inventor: BURLINSON ROY FREDERICK
IPC: F16J3/02
Filed: 1955-06-03
Abstract: 792,417. Pressure gauges; indicating-apparatus. BAILEY METERS & CONTROLS, Ltd. June 1, 1956 [June 3, 1955], No. 15965/55. Classes 106 (2) and 106 (4). An assembly including two instruments 11, 12, each having a diaphragm 74 movable in response to a pressure difference and moving an index 56 over a scale 57 has one instrument 12 located above the other 11 and the scale 57 vertically elongated. and disposed immediately in front of the instruments 11, 12 with the indexes 56 arranged to move side-by-side. Similar instruments 11, 12 in identical die-cast aluminium alloy cases are located and secured to lower and upper walls of the central portion 3 of a housing 1, with rear cover 4 removable for access to the instruments and transparent window 59, exposed through a hole in a panel 30, vertically or inclined downwardly by the use of alternative clamps 32, 32AX. A lamp 61 illuminates the translucent arcuate scale 57. A number of such housings may be disposed adjacent one another and a single housing may accommodate a plurality of pairs of instruments. Pressures, whose difference is to be measured by the instrument 11, are applied through nipples 26, 27 to either side of the diaphragm 74, which is sandwiched between central clamping plates 91, carrying a post 94, Fig. 10, connected by a pin 95 to a biasing spring 96 and by a resilient wire pin to an arm 170, the spring 96 and arm 170 being secured together by rivets 175. At its rear end the arm 170 carries a magnet 196, Fig. 11, which acts near a thin diaphragm 205 on another magnet 217 carried outside by a tray 210 pivoted to the case by two short, weak spring strips 212, thus transmitting movement of the diaphragm to a counter-balanced index arm 50, pivoted on a spindle 225 and linked to the tray 210 by a spring 242 and C-shaped spring 240, the transmission ratio being adjustable by means of a screw 249. If one of the pressures is atmospheric, the diaphragm 205 can be removed and the magnetic coupling avoided by extending the arm 170 outside the case. To make the index arm 55 of the inverted instrument 12 move in the same sense as the adjacent arm 50, the spring 240 is attached to the pointer moulding 226 further back so that the spring links act on the other side of the spindle 225. The biasing spring 96 is clamped to a beam 100, Figs. 6 and 7, between pairs of plates 107, 108 and 110, 111, the latter being adjustable along the spring 96 to vary its rate. The beam 100 is pivoted to the case by a short leaf-spring 102 and is supported near its other end by a lever 132 pivoted on a pin 140 in the case. A rod 127 is pivoted to the beam 100 on a pin 128 and to the lever 132 by a pin 134 working in a slot against a screw 135 which limits downward movement under the bias of a spring 126. The screw 135 thus provides for coarse adjustment. Fine adjustment of zero is obtained at the front of the instrument from a screw 149 through a camming action on the end of the lever 132. The range of pressure 'differences to which the instrument is adapted to respond may be changed by replacement of the biasing spring and the maximiun range with any particular spring may be increased by providing a set of diaphragm masking plates. Specification 792,416 is referred to.