GB289761A - Pressure gauges - Google Patents

Abstract

289,761. Schrader's Son, Inc., A., (Assignees of Wahl, J., and Melzer, O.). April 30, 1927, [Convention date]. Pneumatic tyre pressure gauges. -A gauge for use with both high and low pressure tyres comprises a casing, a pressure responsive member in said casing, resilient means resisting movement of this member, and secondary resilient means adapted to supplement the first when the member has moved a predetermined distance. A second tube H open at both ends is located within the tubular casing b and is provided with a piston E between which and an inturned flange h on the end of the tube H is a relatively weak spring J. The piston rod e passes through the opening in the end of the tube H and the upper half is reduced in diameter forming a shoulder e<1>. Surrounding the tube H within the casing b is the loading spring F the lower end of which is anchored to a fixture K at the lower end of the casing b. The upper end of the spring F is connected to a cup-shaped plunger L formed with an opening through which the reduced portion of the piston rod moves freely, but through which the shoulder e<1> cannot pass. A hollow member G forming an expansion chamber is provided between the usual holes g<1>, g<2> and is clamped between the usual valve depressor part D and a packing h<1> closing the tube H. For balloon tyres, the weak spring J only is called into use, but at higher pressures the shoulder e<1> engages the flange L and the stronger spring is brought into play. The pressure indicia are uniformly spaced on the indicating member C and are arranged in arithmetical progression the common difference for the lower half of the scale being greater than that for the upper part. The tube b is spun inwardly at the upper end to prevent the member C being pushed out of the tube and the member C is held in any position reached by a friction ring.