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No. 6 Distributing Valve In the ideal sketch of Fig. 5, the pressure chamber and application chamber were shown in comparatively the same size as the regular auxiliary reservoir and brake cylinder of the automatic-brake system, and it was explained that the ratio of pressure supply to the application chamber and application cylinder conforms to the normal pressures obtained in brake cylinders of the common automatic system; as long as the sizes of an auxiliary reservoir and brake cylinder are proportionately the same their actual sizes may be reduced or increased to any extent without changing the ratio of equalization of pressure between them; and as the sole duty of their E-T counterparts are to furnish pressure to the comparatively small application cylinder, the reservoir containing the pressure chamber and application chamber is made so small as to take up but little room.

Referring to Fig. 7: It should be understood at first that the equalizing portion and pressure chamber are used in automatic applications only, service reductions of brake-pipe pressure causing the equalizing valve to connect the pressure chamber to the application chamber and application cylinder, allowing air to flow from the former to the latter two-to the application chamber, for expansion to the pressure equivalent to that which is desired in the brake cylinders, and to the application cylinder as the actuating power to be applied to the

application side of piston 10 (upper portion). The upper slide valve, 5, connected to the spindle, or stem, of piston 10, holds main-reservoir pressure above it and admits a graduated amount of it to the brake cylinders when the locomotive brake is applied-an amount to correspond to the pressure in the application cylinder—and is called the “application valve,” while the under one, 16, is used to release the pressure from the brake cylinders and is named the “exhaust valve”; in Fig. 7 the space between piston 10 and the head, 7, is the application cylinder, and the whole space to the right of piston 10 as far as cap-nut 22 is in permanent connection with the locomotivebrake cylinders; any greater pressure in the application cylinder than may be in the brake cylinders will, it can be plainly seen, force the application piston, 10, to the right, to close the exhaust valve and open the application valve, admitting main-reservoir air to the brake cylinders until their pressure equals that in the application cylinder; also, any variation of applicationcylinder pressure will be exactly duplicated in the locomotive-brake cylinders, and the resulting pressure maintained regardless of almost any brake cylinder leakage.

It is obvious that the pressure supply to the brake cylinders of the engine and tender is thus practically unlimited, but the limit has been found in some few

Details of Distributing Valve cases when the brake-cylinder piston-packing-leathers have been partially blown out, or one of the brakecylinder pressure-supply pipes has become broken off, and the braking pressure has escaped faster than it could be resupplied through the very large port of the application valve, or faster than the pump could com

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Copyright, 1909, by The Norman W. Henley Publishing Co. Fig. 6.—No. 6 Distributing Valve and Double-chamber Resorvoir.

CYLS—brake cylinder pipe; BP-brake pipe.

press it. The whole operation of the locomotive brake, therefore, consists in admitting and releasing air pressure into or out of the application cylinder; in independent applications, directly through the independent brake-valve; in automatic applications, by means of the equalizing portion and the air stored in the pressure chamber.

The well-known principle embodied in the Westinghouse quick-action triple valve, by which it gives a high brake power in emergency applications, and a sufficiently lower one, in full-service applications, to provide a desired protection against wheel sliding, is embodied in the No. 6 distributing valve, but without the violent shock to the brake rigging from cylinder piston to brake shoes that occurs at an emergency application of the quick-action triple valve, and the venting of brake-pipe air is not included as an emergency feature unless specially demanded as an adjunct to the standard equipment; the emergency increase of application-cylinder pressure is accomplished by cutting off the application chamber from it, when the pressure chamber will equalize with the quite small application cylinder at a greatly increased pressure that will be followed by a correspondingly high brake-cylinder pressure.

Names of Operating Parts


All of the operating parts are plainly shown in Fig. 7; and the faces and seats, and plan views of the equalizing slide valve and its graduating valve, are shown in Fig. 8. In connection with a study of Figs. 2 A, 2 B, and Fig. 6, the piping connections of Fig. 7 and the connecting ports between the reservoir section and the valve section will be readily understood. The SAFETY VALVE is an essential part of the distributing valve that will be described in detail further along. Referring to Figs. 6 and 7, the names of parts of this apparatus are as follows:

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2, Body. 3, Application-Valve Cover. 4, Cover Screw. 5, Application Valve. 6, Application-Valve Spring. 7, Application-Cylinder Cover. 8, Cylinder-Cover Bolt and Nut. 9, Cylinder-Cover Gasket. 10, Application Piston. II, Piston Follower. 12, Packing-Leather Expander. 13, Packing Leather. 14, Application-Piston Nut. 15, Application-Piston Packing

Ring. 16, Exhaust Valve. 17, Exhaust-Valve Spring. 18, Application-Valve Pin. 19, Application-Piston Graduating

Stem. 20, Application-Piston Graduating

Spring. 21, Graduating-Stem Nut. 22, Upper-Cap Nut. 23, Equalizing-Cylinder Cap. 24, Cylinder-Cap Bolt and Nut.

25, Cylinder-Cap Gasket.
26, Equalizing Piston.
27, Equalizing-Piston Packing-Ring.
28, Graduating Valve.
29, Graduating-Valve Spring.
31, Equalizing Valve.
32, Equalizing-Valve Spring.
33, Lower-Cap Nut.
34, Safety Valve.
35, Double-Chamber Reservoir.
36, Reservoir Stud and Nut.
37, Reservoir Drain-Plug.
38, Distributing-Valve Drain-Cock.
39, Application -Valve-Cover Gasket.
40, Application-Piston Cotter.
41, Distributing-Valve Gasket (not

42, Oil Plug.
43, Safety-Valve Air Strainer.
44, Equalizing-Piston Graduating

Sleeve (numbered 60 on all

subsequent plates).
45, Equalizing-Piston Graduating-

Spring Nut.
46, Equalizing-Piston Graduating


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