GB348351A - Improvements in or relating to release valves for pneumatic buffers and the like - Google Patents

Abstract

348,351. Dynamometers. S P A VEN, L. C., Victoria Works, Millhouses, Sheffield. April 26, 1930, No. 12873. [Class 106 (ii).] In a pneumatic buffer used to measure a force applied to its head, an exhaust passage is provided through the piston-rod which is controlled by a valve actuated by the head so that the pressure fluid is released when the applied force is removed. The device is used in connection with apparatus for measuring the braking force applied to a vehicle wheel. The vehicle is run on to four platforms, each of which can move longitudinally in the direction of movement of the vehicle and each of which engages the short arm of a bell-crank lever, the long arm of which engages the head of the device shown in Fig. 3. Each cylinder 22 is connected to a pressure gauge by a pipe 14. The rod 20 of the piston 18 is grooved on its cylindrical surfaces and has a passage 23 communicating with the cylinder which is widened at its outer end to receive the stem 25 of the head 24 the end 26 of the stem forming a valve face to engage a seating 27. A cotter 28 passed through a slot in the piston-rod and fixed to the stem 25 limits upward movement of the stem relative to the piston-rod. A spring 30 normally holds the head and piston in the position shown. In use the vehicle is run on to the platforms and the brakes are applied causing the platforms to slide and through the bell-crank levers force down the pistons, the force being read off on the gauges which are grouped together. When the vehicle is removed the pistons are returned by the springs, the valves opening to atmosphere so that the gauges all read atmospheric pressure.