Patent GB-190617254-A (GB)
Title: Improvements relating to Pneumatic Braking Systems
Inventor: IVANOVSKI THADDE
Filed: 1906-07-31
Granted: 1907-08-31
Abstract: 17,254. Ivanovski, T. July 31. Brakes.-A distributor for compressed-air brakes, which is adapted to permit a graduated application and release of the brakes and to ensure that the variation of the brake-cylinder pressure is always proportional to the alteration in train-pipe pressure, is of the kind provided with a small supplementary reservoir and diaphragms of varying diameters so that its operation will be independent of the pressure in the auxiliary reservoir, and it may be fitted with an accelerator for venting the train-pipe to the brake cylinder and the atmosphere in emergency applications. The distributor, shown in Fig. 1, is connected to the train-pipe at a, to the auxiliary reservoir at b, and to the brake cylinder at c, these three connexions corresponding to those of the ordinary Westing- house triple valve, so that the latter may be readily replaced on a vehicle by this distributor. The small supplementary reservoir is connected at d. The piston P, which actuates the distributing slide valve T, is connected to diaphragms D', D<2>, D<3> of different areas. The space between the diaphragms D', D<2> is always in communication with the small reservoir, and that between D<2>, D' with the brake cylinder. The brake-cylinder connexion c communicates with a port n in the slide-valve seat, and the auxiliary-reservoir connexion b with another port therein (not shown). In the running position of the slide valve, Fig. 5, the brake-cylinder port n is connected, through a groove k in the slide valve, with the exhaust port e. Air from the train-pipe can pass through a passage a<1> to the space beneath the diaphragm D', and, through a port p, to the space between the diaphragms D<1>, D<2> and so to the small reservoir. Air also passes through grooves t in the slide-valve seat and a right-angled groove q in the slide valve to the auxiliary reservoir port. On reducing trainpipe pressure to apply the brakes, the piston P falls until the supporting-plate W of the spring R<1> is arrested by a stop. In this position, Fig. 6, the slide valve obturates the port p, and the connexion between the grooves t, q is closed, so that the auxiliary and small reservoirs are isolated from the train-pipe and from one another, while the brake cylinder is still connected to the exhaust. As the train-pipe pressure continues to fall, the piston P descends farther until the supporting- plate X of the spring R<2> is arrested. The slide valve is now in the " neutral " or " complete isola- " tion" position, Fig. 7, in which the two reservoirs are still isolated, and the brake cylinder is closed to the exhaust. On a further reduction of train-pipe pressure, the piston descends until a nut on the top of its stem strikes against the plate X. The slide valve now occupies the position shown in Fig. 8, in which the two reservoirs are still isolated from the train-pipe and from one another, and the groove q connects the brake - cylinder port n with the auxiliary - reservoir port. Air flows from the auxiliary reservoir into the brake cylinder until the brake-cylinder pressure, acting on the differential area of the diaphragms D<3>, D<2>, moves the slide valve up again into the "neutral" position, Fig. 7. The brake-cylinder pressure then bears a relation to the fall in train-pipe pressure depending upon the areas of the diaphragms D', D<2>, D<3>. When the driver admits compressed air to the train-pipe to release the brake, the slide valve is moved up again to the position of Fig. 6 and the brake-cylinder pressure falls to an extent depending upon the areas of the diaphragms and the reduction of train-pipe pressure, after which the slide valve returns to the "neutral" position. Further iccreases in train-pipe pressure similarly produce corresponding reductions in brake-cylinder pressure, and when the brake cylinder has been completely discharged the valve returns to the running position, Fig. 5. Fig. 17 shows the distributor fitted with an accelerator. Air from the train-pipe at M passes through a small orifice N in the diaphragm D' and along a passage n<1> to the accelerator reservoir H ; it can also flow into the distributor, through the orifice a, and charge the reservoirs, as described above. In service applications, the pressures can equalize through the orifice N without actuating the accelerator. In emergency applications, however, the sudden decrease of pressure causes the diaphragm D' to rise, unseating the valve K, and allowing train-pipe air to flow to the brake cylinder through a valve K<2>, and also, if the cover Z be removed, to the atmosphere, the distributor being actuated to discharge the auxiliary reservoir into the brake cylinder as usual. The pressure above the diaphragm D<5> assists the spring R<3> in keeping the valve K closed.