Fluid-pressure and analogous brake systems – Multiple control – Fluid and electric
Reexamination Certificate
1999-08-24
2001-05-08
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple control
Fluid and electric
C073S039000, C073S121000
Reexamination Certificate
active
06227625
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to end-of-train (EOT) radio telemetry systems used in the railroad industry. More particularly, the invention pertains to a hand held device that can be used to test whether an EOT unit of a two-way EOT radio telemetry system is operating properly.
BACKGROUND OF THE INVENTION
The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
As shown in
FIG. 1
, a typical freight train
1
includes one or more locomotives
2
, a plurality of railcars
3
and a pneumatic trainline known as the brake pipe
4
. For a freight train headed by a locomotive equipped with a conventional pneumatic brake control system, the brake pipe
4
is the only means by which service and emergency brake commands are conveyed from the lead locomotive to each railcar in the train.
The brake pipe
4
is essentially one long continuous tube that runs from the lead locomotive to the last railcar in the train. As shown in
FIG. 2
, it is actually composed of a series of pipe lengths
4
a
, with one pipe length secured to the underside of each railcar. At the end of each pipe length is a glad hand
7
. The brake pipe
4
is formed by coupling the glad hand
7
on the end of each pipe length
4
a to the glad hand of another such pipe length on an adjacent rail vehicle. It is to this brake pipe
4
that the pneumatic brake equipment on each railcar connects via a branch pipe
8
. As is well known in the railroad industry, by moving the automatic brake handle
21
located in the locomotive, the train operator can control how much, if any, pressure is contained within the brake pipe
4
and thus whether, and to what extent, the train brakes will be applied. The positions into which the brake handle can be moved 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 handle
21
toward the full service position causes the brake pipe pressure to reduce incrementally.
The pneumatic brake equipment on each railcar includes two storage reservoirs
9
and
19
, one or more brake cylinders
11
and at least one pneumatic brake control valve
12
such as an ADB, ABDX or ABDW type valve made by the Westinghouse Air Brake Company (WABCO). The pneumatic brake control valve
12
has a service portion
13
and an emergency portion
14
mounted to a pipe bracket
15
. The pipe bracket
15
features a number of internal passages and several ports. Each port connects to one of the interconnecting pipes from the railcar such as those leading to the brake pipe
4
, the brake cylinder
11
and the two reservoirs
9
and
19
. It is through the ports and internal passages of the pipe bracket
15
that the service and emergency portions of the brake control valve
15
communicate fluidly with the pneumatic piping on the railcar.
It is well known that the pressure level within the brake pipe
4
determines whether the brake control valve
12
will charge the reservoirs
9
and
19
or deliver pressurized air previously stored in one or both of these reservoirs to the brake cylinders
11
. By changing the pressure within the brake pipe
4
, the brake pipe can be used to convey release, service and emergency brake commands to the pneumatic brake equipment on each railcar in the train. In response to a release brake command (i.e., when brake pipe pressure is restored to its maximum level as set by the train operator), the service portion
13
of brake control valve
12
not only charges the two reservoirs
9
and
19
with the pressurized air it receives from the brake pipe
4
but also vents the brake cylinders
11
to atmosphere thereby causing the brakes on the train to release. In response to a service brake command (i.e., when brake pipe pressure is reduced at a service rate), the service portion
13
supplies air from only one of the two reservoirs to the brake cylinders
11
so as to apply the train brakes. How much the brake pipe pressure is reduced, and thus the magnitude of the service brake application, depends on how far the handle
21
is moved towards the full service position. In response to an emergency brake command (i.e., when the brake pipe pressure is reduced to zero at an emergency rate), the emergency portion
14
of brake control valve
12
supplies air from both reservoirs
9
and
19
to the brake cylinders
11
so as to apply the train brakes fully. The emergency portion
14
also accelerates the pressurizing of the brake cylinders
11
by venting the brake pipe
4
on the railcar.
On each railcar and locomotive, each brake cylinder
11
converts to mechanical force the pressurized air it receives from its corresponding brake control valve
12
. From the brake cylinders this force is transmitted by mechanical linkage (not shown) to the brake shoes (not shown) causing the brake shoes to be forced against, and thus to stop or slow the rotation of, the wheels of the rail vehicle. The magnitude of the braking force applied to the wheels is directly proportional to the pressure built up in the brake cylinders
11
. For a freight train equipped with the conventional pneumatic brake system, it is thus the pressure level within the brake pipe
4
that determines whether and to what extent the brakes will be applied.
For a train headed by a locomotive equipped with an ECP (electrically controlled pneumatics) based brake control system, release, service and emergency brake commands are conveyed electrically to the ECP brake - equipment on each railcar of the train via a two wire ECP trainline (not shown). The ECP brake equipment (not shown) on each railcar is essentially the same as the railcar brake equipment previously described, except for the service portion
13
of the brake control valve. As is well known in the art, a car control unit (CCU), one or more pressure transducers and various pneumatic and electropneumatic valves are used in lieu of the service portion. The pressure transducers are used to monitor pressure in the brake pipe and the brake cylinders as well as the pressure in the two reservoirs. Supplied from a 74V dc power line of the MU cable in the locomotive, the ECP trainline operates at a nominal 230V dc to provide power to the ECP brake equipment on each railcar.
In a manner well known in the railroad industry, by moving the brake handle of the master controller in the locomotive, the train operator can transmit along the ECP trainline the desired brake command to the ECP brake equipment on each railcar in the train. Controlled ultimately from the locomotive, each CCU is connected via branch wiring to the ECP trainline from which it receives the electrical brake commands issued by the master controller. The degree of brake application ordered by the master controller is typically conveyed in terms of a percentage of the brake cylinder pressure required for a full service application of the brakes. For example, zero percent (0%) is typically designated for a release of the brakes, 15% for a minimum service brake application, 100% for a full service brake application and 120% for an emergency application of the brakes. According to the dictates of the particular electrical brake command transmitted from the locomotive, each CCU controls its electropneumatic valves through which pressurized air can be supplied to or exhausted from the brake cylinders under its control.
For railcars equipped with ECP brake equipment, the brake pipe still serves as the source of pressurized air from which to charge the reservoirs on each railcar when the brakes are released. During service and emergency braking, it is still from one and both reservoirs, respectively, that pressurized air is delivered to the brake cylinders to apply the railcar brakes. In the ECP brake control system, however
Bartz C. T.
James Ray & Associates
Schwartz Christopher P.
Westinghouse Air Brake Company
LandOfFree
Two way field tester for EOT device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Two way field tester for EOT device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two way field tester for EOT device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2568553