Apparatus for Locating a Malfunctioning Brake Control Valve on Train

This invention relates to a method for rapidly locating a malfunctioning brake control valve that is causing an undesired emergency brake application to occur.

It is a well-known fact that freight trains can be as much as one mile or more in length. Accordingly, when a brake control valve malfunctions, it causes the brakes on the entire train to apply full emergency pressure and the entire train stops. The train crew must endeavour to find the car which has the malfunctioning brake control valve. In addition, the entire train must be walked from one end to the other and visually inspected to assure that no damage has been done during the emergency stop, or that there is no reason other than a malfunctioning brake control valve, to have caused the emergency brake application.

When the car with the malfunctioning brake control valve is located, the brakes in this car can be deactivated by closing a cock in the branch pipe from the main brake pipe to the brake control valve. At the first opportunity, the car with the malfunctioning control valve can be switched out of the train and repaired. However, means presently available to locate a malfunctioning brake control valve that is causing undesired emergency brake applications are restricted to very time-consuming procedures such as the one outlined below:

1. Close the angle cock on the brake pipe at approximately the middle of the train when the train is stationary. This will isolate the cars to the rear of the point where the angle cock is closed.

2. Make a brake application with the brake valve located in the operating cab of the locomotive. If the malfunctioning brake control valve is located in front of the point at which the angle cock was closed, it will initiate undesired emergency brake application. However, if the malfunctioning brake control valve is located in the rear portion, no emergency undesired application will result.

3. Assuming that a malfunctioning brake control valve is in the section of train in front of the point at which the angle cock was closed, it is then necessary to continue closing angle cocks and making brake applications gradually isolating sections of the train until such time as the car with the malfunctioning brake control valve is found. It must be realized that a malfunctioning brake control valve that is causing undesired emergency brake application cannot be found by mere visual inspection. It should, therefore, be appreciated that much time would be saved if some technique could be devised for indicating the malfunctioning brake control valve either on the road or after arrival at an intermediate terminal.

It is an object of this invention to provide a system for immediately indicating the location of a malfunctioning brake control valve on a train.

Another object of this invention is the provision of a novel and useful brake control valve signalling system.

The foregoing and other objects of the invention are achieved in an arrangement wherein the compressed air brake pipe at the head end of the train and at the rear end of the train are equipped with pressure actuated transducers, each of which when actuated can transmit a radio frequency (RF) signal at a different frequency or modulation to a radio receiver which may be located either with the train engineer or with the last car on the train. It is well known that the propagation wave of an emergency air reduction in the compressed air brake train line moves from the point at which air pressure drop is initiated, in both directions to each end of the train at a rate of 930 feet per second. Accordingly, the transducers at the front and back end of the compressed air brake line will be triggered by the moving air at a time determined by their distance from the location of the malfunctioning brake control valve which initiates emergency brake application.

One of the RF signals which is transmitted by the transducer at the front end of the train is received by the radio receiver and is applied to a first counter which is assigned to counting the interval elapsing after receiving that signal. The RF signal from the rear end of the train, which has a different frequency or modulation than the one transmitted from the front end of the train, is also received by the radio receiver and applied to initiate the operation of a second counter which is assigned to count the interval elapsing after receipt of the signal from the rear end of the train. Either both counters can be stopped manually after both counters have started running or, the first of these two counters which counts up to its full count turns itself off and also turns off the other counter. The difference in the count between the manually stopped two counters, or between the full count and the count in the counter which has not made a full count, represents the difference in time between the arrival of the signals at the front end and the rear end of the train. If the first counter has a less than full or lower count, then the bad order brake control valve is located between the middle of the train and a rear end. If the second counter has the remaining or lower count, then the bad order brake control valve is located between the middle of the train and the front end of the train. The distance in feet from one end or the other end of the train to the point of initiation of the signal in the air brake system, as indicated by which of the two counters has the higher count, is one-half of the length of the train in feet, minus 465 feet, times the difference in the receipt of the two time signals, as indicated by the difference in count between the two counters. If clock pulses used to drive the counters are generated at 465 pulses per second, the count difference indicates the distance of the defective brake control valve from the center of the train, towards the location of the first transducer to have been actuated for transmitting an RF signal.

FIG. 1 illustrates a brake control line of a freight train with two transmitting transducers connected thereto in accordance with this invention.

FIG. 2 is a schematic representation of the air brake system on a car of a train.

FIG. 3 illustrates the equipment required at one end of the train, in accordance with this invention.

As previously stated, a brake control valve is located on each car in a long train. The brake control valve normally operates to permit air to flow from the auxiliary reservoir under the car to the brake cylinder, causing the brake shoes to press against the wheels. However, it has an additional function when an emergency brake application is needed. In order to obtain this emergency function, the pressure in the brake pipe must be rapidly reduced. When this rapid reduction is sensed by the brake control valve, it permits air from both the auxiliary and emergency reservoir to flow directly to the brake cylinder and at the same time opens a connection between the brake pipe and atmosphere. The purpose of this opening is to cause a rapid reduction of the pressure in the brake pipe throughout the train when an emergency stop is needed thus causing the brakes to apply very rapidly and with increased pressure.

In the event of a malfunctioning brake control valve, there is presently considerable delay in locating this malfunctioning brake control valve either on the road or after arrival at an intermediate terminal or both. This causes long and serious delays. In accordance with the invention, as shown schematically in FIG. 1, the air brake pipe 10 which extends throughout the train, by virtue of coupling together the brake pipes on each car, has a pressure actuated radio transmitting transducer 12 connected to the brake pipe at the front end of the train and a second pressure actuated radio transmitting transducer 14 (the radio of which transmits a signal on a different frequency or with a different modulation) connected to the brake pipe at the rear end of the train. The front end transducer 12, is designated as transducer No. 1, which when actuated transmits a signal which is modulated so that it is different from the signal transmitted by transducer 14 at the rear end of the train, which is designated as transducer No. 2. Transducer 1 and 2 include pressure actuated switches which respond to a drop in the brake line pressure which exceeds a predetermined value, such as experienced by the malfunction of a brake control valve. The pressure actuated switch turns on a radio transmitter. Pressure actuated switches which can turn on a portable radio transmitter are well known. The small arrows extending from the brake pipe 10 extend to the brake system 11 on each car.

FIG. 2 shows a schematic drawing of the brake system on a car. Whenever the cars making up a train have more than 60 feet of brake pipe length, an additional emergency vent valve 16 is used on each long car. This is known as a No. 8 vent valve. When the rate of flow of air in the brake pipe exceeds the normal service level and reaches the emergency level, the No. 8 vent valve opens to vent the brake pipe to emergency, in addition to the brake control valve performing this function.

Also connected to the brake pipe is the brake control valve 18 which, in response to pressure signals from the brake pipe, permits air to flow from the auxiliary reservoir 22 to the brake cylinder. When the pressure in the brake pipe is rapidly reduced at the emergency rate, the brake control valves operate so as to permit direct connection between the auxiliary reservoir and an emergency reservoir 24, and the brake cylinder so as to rapidly build up emergency brake pressure. In addition, the brake control valve 18 vents the train line directly to atmosphere. The air reservoirs 22 and 24, when the brakes are not in operation, are charged through special charging ports in the brake control 20.

Assuming that the length of the train in feet equals L, the distance from one end of the train to the location of a malfunctioning brake control valve which has initiated emergency application may be represented by X, therefore, the remaining length of the train equals (L-X).

It was previously stated that the propagation rate of an emergency brake application moves from the point at which the emergency is initiated at 930 feet per second. If t.sub.1 is the time required for the emergency brake application initiated from the malfunctioning brake control valve to reach the front end of the train and t.sub.2 is the time required for the emergency brake application to reach the rear end of the train from the location of the malfunctioning brake control valve, then an equation may be established as follows:

Referring now to FIG. 3, there may be seen a schematic drawing of the equipment required at one end of the train for determining the distance of the malfunctioning brake control valve, which equipment has been rendered operative by the emergency brake application initiated by the malfunctioning brake control valve. Radio receiver 30 will receive discrete signals from both transducers at different times, depending upon the location of the malfunctioning brake control valve. The radio receiver will apply the received signals from the first and second transducers, which are modulated so that they are distinguishable by the radio receiver, to a first gate 32, when the signal is received from transducer No. 1, and to the second gate 34 when the signal is received from transducer No. 2. When either of the gates are enabled, they permit pulses from a pulse source 36 to be applied to the counters respectively 38 and 40.

Enabled gate 32 permits pulses from a source to be applied to a counter 38, which commences to count in response to these pulses. Enabled gate 34, permits pulses from source 36 to be applied to the counter 40 which commences to count in response to these pulses. In one embodiment of the invention, whichever one of the counters 38 or 40 attains its full count first, that counter's last count renders gates 32 and 34 inoperative and, as a result, the counters stop counting. The difference between the counts displayed by the counters is the equivalent time, t.sub.2 - t.sub.1 , or the difference in time for the propagation of a signal from the point at which it occurred on the train to the two ends of the train. By using the formula previously given, this time difference may be converted into distance.

If counter 38 displays a greater count than counter 40, then, the point at which the emergency brake application was initiated, by a malfunctioning brake control valve, is located between the center of the train and the front. The distance X calculated is the distance from the front end of the train. If counter 40 displays the greater count, then the emergency brake application was initiated at a point between the center and the rear end of the train. The calculated distance X this time is the distance from the rear end of the train.

If the pulse source frequency 36 is made such that the counters count at 465 counts per second, and indicate their counts, then the difference will be equivalent to the distance in feet from the center of the train towards the transducer which keyed the counter with the higher count. This can be seen from the equation given previously, if placed in the form (1/2 -X) = 465 (t.sub.2 - t.sub.1).

In another embodiment of the invention, any time after the two counters start counting, a switch 42 may be activated. This applies a voltage from a disenable voltage source 44 to the gates 32 and 34. This disenables the gates, blocking further application of pulses to the counters whereby their counting is stopped. The difference in counts of the counters at that time is an indication of (t.sub.2 - t.sub.1).

There has accordingly been described and shown above, a novel and useful system for rapidly determining the location of a malfunctioning brake control valve so that appropriate corrective action can be taken.