GB274228A - Improved pressure registering apparatus - Google Patents

Abstract

274,228. Ashton, H. April 27, 1926. Pneumatic-tyre and piston-and-spring pressure gauges. - Several constructions are described which when a definite pressure is reached release air with a hissing noise. In the form shown in Fig. 1, a piston moves in a cylinder connected at the lower end with the pressure container. The piston rod D passes through the cylinder end between which and the piston is a spring. A hole A is provided on the side of the cylinder and becomes uncovered when the pressure forces the piston above it. A cap E holds the piston down when the gauge is out of use. The hole is sometimes fitted with a valve, for instance an elastic band, housed in a slot B. A sleeve C is also provided to prevent the valve from functioning. In a modification shown in Fig. 2, the cylinder is fitted with a plunger having a square piston rod adapted to pass through a similar shaped hole in a plug P screwed into the cylinder which is screwed internally to about half-way down. The cylinder is slotted and a loose washer placed on the piston rod has a projection K passing through the slot H and thus serving as an indicator. The tension of the spring F is adjusted by turning the piston rod by means of the milled head L. The outlet A and valve are fitted as in the first form. In a further modification, a loose square graduated tube passes through the cylinder cover and through the plug to rest on the piston. A graduated tube may be formed in one with the plug or may be loose and provided with projections to engage holes in the plug. The piston may be formed on the underside with a screwed extension adapted to engage a screwed inlet hole by pressing upon and twisting the top of the piston rod so that the apparatus may oe locked when out of use.