Patent GB-190429067-A (GB)
Title: Improvements in and connected with Brakes for Railway Cars.
Inventor: BARKER WILLIAM LOUGHRIDGE
Filed: 1904-12-30
Granted: 1905-02-16
Abstract: 29,067. Barker, W. L. Dec. 30. Brakes; axle-trucks or undercarriages. - The brakes are applied by the weight of the vehicles, and are held off by fluid pressure or by mechanism operated by hand. The arrangement of the brake mechanism is such that the pressure applied to the wheels of each bogie of the train is proportional to the momentum of the bogie and of the load which it carries, and, further, that the brake is applied first to the more heavily loaded bogies and lastly to the lightest. Fig. 2 shows a transverse section through one of the bogies. The bolster 3 and the plank 4 on which it is supported by the springs 4<a> can move vertically between the transoms 2, and are supported by forked transverse levers 5, the inner ends of which are connected to the brake lever 12 by a " triple coupler " 9. Whenever the restraining-force which keeps the brakes off is withdrawn, the load on the bolster 3 operates the brake lever 12 through the transverse levers 5, and thus applies the brakes. An additional brake pressure, proportional to the weight of the bogie truck itself, is transmitted to the brake lever by means of adjustable or permanent weights 31 on the levers 5. Fig. 4 shows one arrangement of mechanism for transmitting the force from the brake levers 12 to the brake beams, and the means for upholding the levers 12 by fluid pressure in order to keep the brakes normally off. The brake beams are shown outside the wheels, but they may be placed inside. The mechanism is shown as applied to a car fitted with a brake cylinder 35 and auxiliary reservoir 66 in communication with the usual train-pipe. The restraining-force is transmitted from the piston-rod of the brake cylinder to one of the brake levers 12 by the levers 32, 42 and connecting-links, and to the other brake lever 12 by the levers 32, 46 and connecting-links. In order that release of the brakes may also be effected by hand, the brake-cylinder piston can be pulled out by a lever 37 which is operated by a link 39 connected to a chain which can be wound up by the windlass shown in Fig. 2 at 50. To allow the brakes to be applied gradually when the winch is released, friction screws 54 are tightened so as to press upon one of the pinions of the winch. The air in the brake cylinder also serves as a cushion for the same purpose. Between the brake cylinder 35 and the reservoir 66 a special valve mechanism is employed ; it is shown in Fig. 5 in sectional plan. Air from the train-pipe connection 63 flows into the valve chamber 70, opens a spring valve 74, and charges the auxiliary reservoir through the pipes 73. Another spring valve 74, on the other side of the piston valve 71, is at the same time held open by the end of a spring plunger 76 fitted in the valve 71, so that air from the auxiliary reservoir can flow under the piston valve 71 and through the pipe 72 to the brake cylinder in order to hold the brakes off. If, in an emergency, the train-pipe pressure at 63 is largely reduced, the piston valve moves to the opposite end of its chamber so as to open the brake cylinder to the atmosphere through vents 77 at the same time that it is shut off from the auxiliary reservoir by the closing of the spring valve 74. The brakes are thus applied to the full load on the bogies. If the train-pipe pressure is only moderately reduced, as for a service application of the brakes a similar motion of the valve 71 follows initially, but, when the brake-cylinder pressure at 72 has fallen below the train-pipe pressure at 63, the valve 71 returns far enough to close the vents 77, though it is not pressed with sufficient force to open the spring valve 74. The air which is consequently imprisoned in the brake cylinder will moderate the pressure of the brakes. On restoration of the train-pipe pressure, air from the auxiliary reservoir flows into the brake cylinder and releases the brakes. A modification is described in which the upper spring valve 74 is removed from the valve casing and placed in a branch connecting the pipes 63, 73, and the lower spring valve is dispensed with, the piston valve 71 itself serving to govern the communication between the brake cylinder and auxiliary reservoir. Fig. 15 shows an alternative arrangement of the brake mechanism. While pressure is being restored in the cylinder 35, that one of the brake levers 12 which carries the lesser load will be operated first to release the brake, but when it has moved up to a stop 30 the fulcrum of the lever 32 will be shifted from the end of the rod 45 to that of the rod 44 or vice versÔ, and the more heavily-loaded brake lever will then be operated. The application of the brakes will take place in the reverse order, the heavily - loaded bogies being first served throughout the train.