Electro-pneumatic freight brake control system

#The present invention relates to a brake control system for railroad freight cars and in particular to such a brake control system that integrates electro-pneumatic control of the brake with the conventional automatic pneumatic brake control.

#From the inception of the early Westinghouse air brake, until the present time, compressed air has been employed as the medium by which brake control signals have been transmitted through a train of railroad freight cars, as well as the force by which friction retardation is applied through brake shoes that engage the car wheel treads during braking. As the size of freight cars has increased to provide greater load carrying capacity, and the number of cars capable of being hauled in a train has likewise grown, there have been continued improvements in the air brake system to make it more efficient, in order to provide better stopping ability consistent with the greater demands placed on the air brake system.

#Electro-pneumatic brake control systems are known to extend the capability of the air brake beyond that which is achieved with the conventional automatic pneumatic brake control system presently employed. These improved capabilities are possible due primarily to the fact that the brake control signal can be transmitted instantaneously to each car in the train, whereas propagation of a pneumatic control signal is limited to a value approaching the speed of sound. by instantaneously transmitting a brake control signal to each car of a train, not only is the time required to initiate braking action on all of the cars reduced, but in-train forces, due to disproportionate brake buildup timing between the cars, are better controlled. This permits greater brake force to be employed to achieve shorter stop distance without incurring damage to car lading and couplers, and without creating the potential for a train derailment.

#These and other objects and advantages of the invention will become apparent from the following explanation when taken in conjunction with the accompanying drawings in which:

#FIG. 1 is a partial diagrammatic view of a conventional pneumatic freight brake control valve device with which an electro-pneumatic brake control system shown in block diagram form is operatively combined; and

#FIG. 2 is a chart showing the status of the application and release magnet valves in different operating conditions of the electro-pneumatic brake system.

#Referring to the drawing, there is shown a partial view of a conventional ABD, ABDW or ABDX type brake control valve device 14, such as may be employed on a railroad freight car. Typically, such railroad freight cars include in addition to a brake pipe 1, a brake cylinder 3, an emergency reservoir 2, an auxiliary reservoir 5, and a retainer valve 10. The ends of brake pipe 1 are provided with flexible hose and couplings (not shown) for connecting with the counterpart hose and couplings on adjacent ends of an adjoining freight car in a railroad train. As is well known, brake pipe 1 is charged with compressed air stored in the main reservoirs on the locomotive of the aforementioned railroad train, the pressure in brake pipe 1 being maintained at a predetermined running pressure when the locomotive brake valve (not shown) is set in release position.

#As is also well known, control valve device 14 is set in its release and charging position, as shown, in response to the pressure in brake pipe 1 being increased, such as when charging the system and when releasing a previous brake application. In this release and charging position of control valve device 14, compressed air is connected from brake pipe 1 to auxiliary reservoir 5 via branch pipe and port 1a, passage b, passage b2, a passage k in slide valve 13 of the service piston 11, a chamber Y under the service piston diaphragm, passage a1, passage a, and supply port and pipe 5a. In turn, compressed air is also connected from chamber Y to the emergency reservoir 2 via passage n in the service piston graduating valve 12, a passage m in slide valve 13, passages e4, e2, and supply port and pipe 2a. Concurrently with the aforementioned charging, brake cylinder device 3 is vented to atmosphere via pipe and delivery port 3a, passages c, c1, slot t in slide valve 13, passage ex, port and pipe 10a, and a pressure retainer valve 10.

#Being conventional, the foregoing pneumatic brake control system is capable of providing service and emergency brake applications in accordance with a reduction in brake pipe pressure at appropriate rates in a well-known manner.