GB669723A - Improvements in or relating to valves for pneumatic tyres - Google Patents

Abstract

669,723. Tyre valves. MASSAT, A. E. L. March 22, 1950, No. 7135/50. Class 135 [Also in Group XXVIII] A tyre valve having means for automatically admitting additional air into the inner tube to compensate for losses comprises a member 1 divided into upper and lower chambers a, b by a piston 5 urged by a spring 19 away from the inner tube 4 and connected by a flexible, non-extensible cable 16 to a point on the inner tube diametrically opposite a threaded sleeve 2 to which the member is connected. The piston 5 has an opening in its upper end 6 controlled by a spring-loaded check valve 7, and screw-threaded members 11, 12, 13, at its lower end to adjusting its position relative to the member 1, the loading of the spring 19 and the tension in the cable 16. The member 1 has a spring-loaded, pressure relief valve 30, an oiler 36, and an inlet chamber 25 having an air filter 27 and communicating through a spring-loaded check valve 21 with the chamber a. The tube is inflated in the usual way through a hollow stem 29 and the check valves 21, 7, to a predetermined pressure. During the running of the vehicle, should the pressure in the tube fall below the desired value, the tyre will on revolution of the wheel be alternately deflated and expanded. On deflation of the tyre, the cable 16 will slacken to permit the spring.19 to urge the piston 5 upwards, whereupon the air in the chamber a is compressed and the valve 7 opened to admit additional air to the tube 4. On expansion of the tyre, the cable 16 pulls the piston 5 downwards whereupon the pressure in the chamber a decreases and the valve 21 opens to admit atmospheric air to the chamber a, which on the next cycle of operations is compressed and transferred to the tube until the pressure therein is restored to its desired value. Should the pressure in the tube rise above its desired value through, e.g. increase in temperature, the excess pressure will be relieved by the valve 30.