GB300754A - Improvements relating to fluid operated brakes for tramway and other rolling stock - Google Patents

Abstract

300,754. Electro-Mechanical Brake Co., Ltd., Cadbury, G. N., and Smith, S. Oct. 11, 1927. Fluid-pressure.-A fluid operated brake for tramway and other rolling stock is provided with an automatic valve which when a predetermined pressure on the wheel brakes is exceeded diverts pressure. fluid to the track brakes and releases the pressure on the wheel brakes. The automatic valve comprises, a pair of large pistons j, k in a cylinder h and a small piston l in a cylinder i. The pistons form a single moving element which is held by a spring u in the position shown so that when the manual control valve is operated to open a valve d and to apply the brakes, pressure fluid is admitted from a reservoir a and a pipe c to a pipe 9, and the piston j, a pipe m and the space between the pistons j, k, pipe o, and the wheel brake cylinder f. Fluid is also admitted from the pipe c by pipes v, x to the cylinder i and acts on one side of the piston l. If the fluid pressure which acts on the piston j exceeds a certain amount the pistons move to their opposite limit, and close the wheel brake supply pipe m open the wheel brake cylinder pipe o to an exhaust port and admit pressure fluid to a pipe p leading to the track brake cylinder g. The supply to the cylinder is also cut off and this cylinder is exhausted through a passages y the space between the cylinders j, k and the outlet q. To release either brake the manual control valve is operated to close the valve d and open a valve e and the pistons are returned to initial position by the spring u, the wheel brake cylinder is exhausted through the valve e and the track brake cylinder through a passage z, the space between the pistons k, l and a passage r. By opening the valve d immediately to full open position the pistons are moved to apply the track brakes only; or this may be done by means of an emergency valve w adapted to connect the pipe v to the pipe q and the pipe x to an exhaust outlet 2. The brakes may be exhausted by means of a passage 3. The pipe p is connected to an automatic valve at each end of the vehicle and is therefore provided with a cylinder s containing a floating-piston t which when one automatic valve acts closes the pipe leading to the uther valve. In a modification the cylinder : i is provided with a spring-controlled release valve adapted to act above a certain pressure and thus allow the automatic valve to operate more readily and the track brakes can be operated at a lower fluid pressure than normally. Also the pipe x is dispensed with and a passage leading from the cylinder i to the space between the pistons j, k is provided.