Fluid-pressure and analogous brake systems – Multiple fluid-receiving devices – Multiple motors
Reexamination Certificate
1998-12-18
2001-02-20
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple fluid-receiving devices
Multiple motors
C303S015000
Reexamination Certificate
active
06189980
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to two basic types of brake control systems, both well known and widely used in the railroad industry: (1) the conventional brake control system by which a locomotive is able to control the brakes on railcars equipped with pneumatic brake equipment; and (2) an ECP based brake control system by which a locomotive is able to control the brakes on railcars equipped with electrically controlled pneumatic (ECP) brake equipment. More particularly, the invention pertains to a system that enables a locomotive equipped with the conventional brake control system to control the brakes on railcars equipped with the newer electrically controlled pneumatic (ECP) brake equipment.
BACKGROUND OF THE INVENTION
The following background information is provided to assist the reader to understand the invention described and claimed below. Accordingly, any terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
For a train headed by a locomotive equipped with the conventional brake control system, a pneumatic trainline known as the “brake pipe” is the only means by which service and emergency brake commands are conveyed to each of the railcars in the train. The brake pipe is essentially one long continuous tube that runs from the lead locomotive to the last railcar in the train. The brake pipe is actually composed of a series of interconnected pipe lengths, with one pipe length secured to the underside of each railcar. The brake pipe is formed by connecting each pipe length via a coupler to another such pipe length on an adjacent railcar. As shown in
FIG. 1
, it is to this brake pipe
1
that the pneumatic brake equipment on each railcar connects via a branch pipe
2
.
The pneumatic brake equipment on each railcar includes two storage reservoirs
3
&
4
, one or more brake cylinders
5
and at least one pneumatic brake control valve
6
such as an ADB, ABDX or ABDW type valve made by the Westinghouse Air Brake Company (WABCO). Under conditions known in the brake control art, the pneumatic brake control valve
6
charges the two reservoirs
3
and
4
with the pressurized air it receives from the brake pipe
1
. It is the pressure level within the brake pipe
1
that determines whether the brake control valve
6
will indeed charge these reservoirs or deliver pressurized air previously stored in one or both of these reservoirs to the brake cylinders
5
. When so pressurized, the brake cylinders
5
convert the pressurized air that they receive from the brake control valve
6
to mechanical force. From the brake cylinders this force is transmitted by mechanical linkage to the brake shoes. The magnitude of the braking force applied to the wheels is directly proportional to the pressure built up in the brake cylinders. Forced against the truck wheels and/or disc brakes, the brake shoes are used to slow or stop the rotation of the wheels. For trains equipped with the conventional brake control system, it is thus the pressure level in the brake pipe
1
that determines whether and to what extent the railcar brakes will be applied.
In addition to the brake pipe, the locomotive has its own pneumatic trainlines including a main reservoir equalizing (MRE) pipe, an independent application and release (IAR) pipe, and an actuating pipe. Within a locomotive consist (i.e., two or more locomotives connected together), the MRE, actuating and IAR pipes of each locomotive connect to the MRE, actuating and IAR pipes of adjacent locomotives. The MRE pipe is used to charge the brake pipe to a normal operating pressure of approximately 90 psi when the brakes are released. Incidentally, it is the pressure within the IAR pipe that controls the delivery of pressurized air to, and thus the operation of, the brakes of the locomotive(s) in the train.
The locomotive also features a multi-wire electrical trainline known as the multiple unit (MU) line cable. The MU line cable consists of twenty seven (27) different electrical lines. As is well known in the railroad industry, the MU line cable contains an alarm line on which the locomotive equipment can convey various signals to alert the train operator of critical conditions occurring in the locomotive. The MU line cable also contains 74V dc power and return lines on which battery power from the locomotive is supplied to the various power consuming devices on the train.
There are many different types of conventional brake control systems in use in the railroad industry. An example of one type of conventional brake control system is the 26-L Locomotive Air Brake Control System manufactured by WABCO. A conventional brake control system, such as the 26-L System, has two brake handles referred to as the automatic and independent brake handles. By placing these handles into the appropriate positions, a train operator in the locomotive can control how the brakes on the locomotive(s) and railcars operate. More specifically, by moving these handles into the proper position, the train operator can control how much pressure will be developed in the IAR and brake pipes, as well as in the other pneumatic trainlines of the train. It is by such control of the pressure level in the brake pipe
1
, for example, that the pneumatic brake equipment on each railcar is controlled.
By moving the independent brake handle, the train operator can direct the conventional system only to apply or release the brakes on the locomotive(s). In contrast, by moving the automatic brake handle, the operator can direct the brake control system to apply or release the brakes on both the locomotive(s) and railcars in the train. The level to which the system reduces or increases pressure within the brake pipe
1
, and thus the amount of braking power exerted by the train brakes, ultimately corresponds to the position of the automatic brake handle. The automatic brake handle can be moved from and in between a release position at one extreme (in which brake pipe pressure is maximum and the brakes are completely released) to an emergency position at another extreme (in which brake pipe pressure is zero and the brakes are fully applied).
The positions for the automatic brake handle include release, minimum service, full service, suppression, continuous service, and emergency. Between the minimum and full service positions lies the service zone wherein each incremental movement of the automatic brake handle toward the full service position causes an incremental reduction in brake pipe pressure. The exact amount by which the brake pipe pressure is reduced depends on how far towards the full service position the brake handle is moved. It is this reduction in pressure that signals the pneumatic brake control valve(s)
6
on each railcar to supply pressurized air from one or both reservoirs to the brake cylinders so as to apply the railcar brakes. The amount of pressure built up in the brake cylinders, and thus the magnitude of the braking force applied to the wheels, is proportional to the amount by which the brake pipe pressure has been reduced.
When the automatic brake handle is moved from within the service zone or above towards the release position, the way in which the brakes operate depend on whether the brake equipment has been designed to allow a graduated release of the brakes. Passenger trains typically feature brake equipment that allows a graduated release of the brakes when the locomotive brake control system is set in the “passenger service” mode of operation. Freight train brake equipment, in contrast, typically permits only a direct release of the brakes.
For direct release equipment, in response to such movement of the automatic brake handle, the brake control system does not command an increase in the pressure within the brake pipe
1
until the automatic brake handle is placed in the release position. Once the pressure in the brake pipe increases above a preset level (e.g., 2 psi), the control system and the railcar brake control valves it affects respond by completely ventin
James Ray & Associates
Schwartz Christopher P.
Talavera Melanie
Westinghouse Air Brake Company
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