USOO583,3325A

United States Patent (19) 11 Patent Number: 5,833,325

Hart (45) Date of Patent: Nov. 10, 1998
54) FREIGHT BRAKE CONTROL USING TRAIN Primary Examiner Robert J. Oberleitner
NET BRAKING RATIO Assistant Examiner Pamela J. Lipka
Attorney, Agent, or Firm-Buchanan Ingersoll, P.C.
75 Inventor: James E. Hart, Trafford, Pa.
57 ABSTRACT
73 Assignee: Westinghouse Air Brake Company,
Wilmerding, Pa. A railway freight brake System for operating vehicles in a
train wherein each vehicle responds in braking situations as
21 Appl. No.: 597,277 if its effective net braking ratio was a desired train net
braking ratio. Embodiments include vehicles receiving a
22 Filed: Feb. 6, 1996 brake Signal and utilizing either a received train net braking
(51) Int. Cl." ..................................................... R60T 1300 ratio or utilizing a stored on-board train net braking ratio to
52 U.S. Cl. ............................. 3037. 303/969. 303/226 control pneumatic equipment on-board the vehicle to pro
58 Field of Search ............................ 303/7, 3, 15, 22.1 duce brake forces on the vehicle generally corresponding to
303?22s, 969. 20 the net braking ratio of the train. Some embodiments use a
common train line control to communicate both train net
56) References Cited braking ratio and brake Signals to the individual vehicle.
Individual vehicles can receive periodic or initial train net
U.S. PATENT DOCUMENTS brake ratio values.
4,402,047 8/1983 Newton et al. ......................... 303/3 X
5,551,765 9/1996 Sich ...................................... 303/20 X 6 Claims, 7 Drawing Sheets

CAR 3. 29
PARAMETERS LOAD SIGNAL
LOC,
PARAMETERS
U.S. Patent Nov. 10, 1998 Sheet 1 of 7 5,833,325
U.S. Patent 5,833,325

SE(XTWN8O|I)S
U.S. Patent Nov. 10, 1998 Sheet 3 of 7 5,833,325

(26,500 LBS NSF)

f
---- g 131,500 LBS CAR WT.
92,950 LBS w
g WT. Y. W
m
(18,590 LBS NSF)
w NBR
NSF --UPPER LIMIT
NBR
LOWER LIMIT
g 10% ON 263,000 LBS
26,300 LBS NSF
6.5% ON 286,000 LBS
18,590 LBS NSF
O
O 50,000 100,000 150,000 200,000 250,000 300,000
CAR WEIGHT-LBS (LOADING)
FIG. 2
U.S. Patent Nov. 10, 1998 Sheet 4 of 7 5,833,325

11OPS

DESRED BCP WS. HANDLE POSITION

HANDL % F.S.
O-3 O
!
(MIN. SERV.) 8- 15.6° 8.0 PSI (FOR ANY BP)
43 +42.2%
t t
(FULL SERV.) 58° 100%
to go go to so go to go
BRAKE CYLNDER PRESSURE-PS
(BCP)

FIG. 3
U.S. Patent Nov. 10, 1998 Sheet 5 of 7 5,833,325

THEORETICAL
(GROSS) SHOE FORCE &
ACTUAL

SLOPE=ANS=N
ABCP
(F2P)

BRAKE CYLINDER PRESSURE-PS

(BCP)
THEORETICAL: GSF CYL AREA k PRESSURE x LEVER RATIO
NSF GFS x EFFICIENCY FACTOR
NET EQUATIONS:
(1) FN = (P-a)*N
(2)2) N = FN/(P-a)= (F-F)
(P-P,)
(3) P = (FN/N)+a
(4) a = P-(FN/N)
WHERE: FN = NET (ACTUAL) BRAKE SHOE FORCE (LBS)
P = BRAKE CYLINDER PRESSURE (PSI)
a - BCP AT ZERO NSF
F PETC = POINTS ORACTUAL CORRESPONDING
WALUES FOR F & P

FIG. 4
U.S. Patent Nov. 10, 1998 Sheet 6 of 7 5,833,325

PREFERRED METHOD
UNIFORM NBR-BCP ALGORTHM
PROPORTIONING EMPTY CARS

RECEIVE BRAKE COMMAND

(BCP & NBR) 51

CALCULATEE/LTRANSiTION
WEIGHT We
Wo (NBR 263,000)/.20
OBTAN ACTUAL WT. 53
WN
54 55
NO CALCULATE NSF
F=(BCP/50.0)*NBRI*(GRL/265,000)
YES
56
/-57
CALCULATE NSF CALCULATE BCP
F=(BCP/50.0)*W*.2 BCPN=(FN/N)+a

BCP-58
FIG. 5
U.S. Patent Nov. 10, 1998 Sheet 7 of 7 5,833,325

UNIFORM NBR-BCP CALCULATIONS

LIMIT EMPTY CARS

CALCULATE COMMON NSF

F=(BCP/500)*NBRI*CAR LOAD CAPACITY

CALCULATE BCP

RE-CALCULATE NSF
F=(BCP/50.0)*W*.2

FIG. 6
 5,833,325
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FREIGHT BRAKE CONTROL USING TRAIN weight rail vehicles requiring leSS braking force than a 200
NET BRAKING RATIO ton freight car. The transit vehicles often operate at very
close intervals between Stops and therefore Seldom reach the
high Speeds of over-the-road freight trains. In addition,
BACKGROUND OF INVENTION transit vehicles often use electrical dynamic braking where
This invention related to railway braking Systems, Spe a portion of the braking results from a regenerative or
cifically braking Systems for railway freight trains. generated electric current on-board each vehicle or pain of
Traditionally, railway freight braking Systems have uti vehicle. Freight train braking on the other hand has tradi
lized a pneumatic brake System that is both operated by tionally relied Solely upon frictional braking on each indi
compressed air and in which the control functions are vidual freight car. Electro-motive regeneration braking may
obtained through utilization of pneumatic valves. Prior also be used on freight locomotives that already have
freight brake Systems included the use of a brake pipe or electrical motors on-board that vehicle. However, freight
pneumatic communication between the locomotive and each cars Seldom have electrical propulsion drive motors con
tained thereon.
individual car in a freight train. The pneumatic brake pipe
was utilized in a multi-function role, including: charging
15 It would be highly desirable that freight cars contain a
reservoirs on-board each individual freight car; instituting braking System which would optimize the braking of the
brake application; and controlling the release of the brakes overall train during their operation over various railroads
on the train. Such Systems generally utilized on-board pneu and various operating parameters. Because the brake equip
matic control valves Such as ABD, ABDW, ABDX, or ment on each individual freight car may be designed using
DB-60 valves, with 26 TYPE Locomotive brake equipment different parameters and the operation conditions vary
or Microprocessor with like EPIC sold by Westinghouse Air depending upon the brake pipe pressure utilized in different
Brake Company. It was the general practice to use identical trains and on different railroads, it would be desirable that
functioning pneumatic control valves and related control the freight brake System accommodate Such variations under
Sequencing on comparably equipped freight cars throughout operating conditions.
25
the train, Such that each car's braking Sequencing would be SUMMARY OF INVENTION
Similar. Freight cars have varying braking capabilities
depending upon the mechanical linkages between the brake The invention relates to a railway freight train brake
cylinder and the brake Shoes. In addition, Some cars may be equipment for operation on-board a railway freight vehicle.
equipped from time-to-time with either empty-load or load The railway freight vehicle has a friction brake which is
Sensing equipment which may vary the pneumatic preSSure actuated by a pneumatic brake cylinder, and the car has a
applied to the brakes based upon the Specific load or weight reservoir which acts as a storage compartment for preSSur
of the individual car. The level of desired brake pressure was ized air. A brake Signal indicative of a desired braking level
controlled by the brake pressure in the brake pipe, commu of Such train is transmitted to each freight car. On-board the
nicating with the locomotive. The advantages of Such prior railway freight vehicle a processor Such as a microprocessor
art System was the utilization of a Single pneumatic com
35 is used to calculate a brake cylinder pressure from the brake
munication running the length of the train. Some of the Signal and a train net braking ratio. The calculated brake
desired characteristics in evaluating a freight brake System cylinder pressure is that which will result in a net shoe force
include the Speed with which braking can be initiated on the same as if the freight vehicle on which the micropro
each individual car, the Specific value of the braking on each ceSSor is located had a specific design netbraking ratio equal
car, regulation of the in-train forces Such that the braking is
40 to the train net braking ratio. By definition the design net
generally shared between cars without excessive pushing or braking ratio of a vehicle is the net or actual brake shoe force
pulling on the couplers connecting the cars, and the accurate derived from 50 psi in the brake cylinder(s) divided by the
regulation of the Speed and deceleration of the freight train car weight. The processor or microprocessor then can con
during overall operation. trol valves to respond to Said calculated brake cylinder
It is desirable to limit in-train forces to reduce any damage
45 preSSure. In Some embodiments an application and release
that might occur to the cargo being carried in each car, and Valve may be used, and in other applications a Single valve
to provide optimum life and reduced maintenance to train may be used. The microprocessor controls the brake cylinder
equipment. preSSure over a portion of the range of braking of Such
vehicle as if Such vehicle had a net braking ratio that was
Current practice often requires that freight cars be utilized 50 generally equal to the train net braking ratio. In Some
over different rail Systems. Such that the Specific operating embodiments the preselected operating train net braking
parameters, Such as brake pipe operating pressures, may ratio can be sent to the individual freight vehicle via the train
vary from System to System. As a result the same car must line, either continuously or periodically. In other embodi
be asked to perform over a variety of Specific operational ments it may be desirable to only Send the net train braking
parameters, which may differ from the optimum design 55 ratio at the initiation period prior to the train being Started.
characteristics for which it was initially built. In Some versions of the invention the train net braking ratio
Utilization of electrical Signals from a locomotive to may be predetermined and Stored in memory on each car.
control brake operation has been utilized in both passenger Some embodiments may also have a default train net brak
trains and transit equipment. Typically, an electrical Signal is ing ratio. Certain train handling Situations, Such as at low
Sent the length of the train with the Signal level controlling 60 braking levels or in grade situations, it may be desirable to
both the propulsion and the desired level of braking. Such utilize braking techniques other than using the train net
electro-pneumatic braking Systems are not generally utilized braking ratio. Other embodiments of the invention are
in freight brake operations due to the vastly different require explained in the following description.
ments between passenger and freight operation. Specifically,
DESCRIPTION OF DRAWINGS
trains and transit equipment consist of a few cars, whereas 65
freight trains often operate with 150 or more cars to a single FIG. 1a is a diagrammatic representation of a railway
train. Transit and passenger vehicles are typically lighter freight train having a plurality of freight cars.
 5,833,325
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FIG. 1b is a diagrammatic view of a railway freight car all cars in a freight train each time the brakes are applied. It
brake System utilizing a microprocessor on-board the car is much more beneficial to optimize the braking effort on
which is utilized in accordance with Some embodiments of each individual car throughout the train, in Some situations
the present invention. to achieve the Smoothest possible train handling and to
FIG. 2 is a graph showing relationship between net minimize the risk of damage to equipment and/or lading, and
braking ratio and car weight. in other Situations to achieve the best overall protection
FIG. 3 is a graph showing brake valve handle position in against wheel over-heating and potential wheel damage.
degrees of rotation in relation to brake cylinder pressure in While applicable to different types of train braking
pounds per Square inch. Situations, each of these objectives insures improved brake
FIG. 4 is a graph showing relationships between brake efficiency and improved performance of train operation over
cylinder pressure and net Shoe force for typical freight car. that which would be achieved with equal brake cylinder
preSSures on each car.
FIG. 5 shows a general flow chart for calculating brake There are three general purposes for which Service air
cylinder pressure from a train net braking ratio and a train brake applications are used on heavy freight trains: brake
brake Signal; in this instance the train brake Signal is train 15 applications to slow or Stop the train; light applications to
brake cylinder pressure.
FIG. 6 shows a flow chart for a general method of control the Slack run-in and run-out in a long train; and
calculating uniform net braking ratio from a train net brak applications to control or maintain the Speed of a train on
descending grades.
ing ratio and a train brake Signal, in this instance a nominal Typically, light to medium applications would be used to
train brake cylinder pressure, BCP. Slow the Velocity of a train, and fill Service applications
DESCRIPTION OF SOME EMBODIMENTS would be used to Stop the train. When grade braking is
Freight trains can be slowed down or Stopped using required, usually only up to one-half of the available full
various degrees of Service brake applications or Stopped by Service brake cylinder preSSure is used. In grade braking
emergency brake application. The conventional pneumatic 25
dynamic braking will often be used on the locomotive to
brake System for freight cars is an equalizing type System, Supplement friction braking on each individual car. When
wherein the auxiliary reservoir pressure reduction generally the total train retarding force exactly matches the grade
matches the brake pipe pressure reduction. The resulting accelerating force, Zero acceleration is achieved and the
brake cylinder pressure is generally directly dependent on Velocity of the train is held constant.
the volume relationship between the reservoir and the brake Emergency brake applications are generally only used
cylinder (including piping, clearance, and the voided piston when it is imperative to Stop a train in the shortest possible
displacement volumes which can vary from car to car). In distance, or as a last resort to control train speed.
emergency brake situations, the auxiliary and emergency When decelerating or stopping a train, the ideal distribu
reservoir pressures are both equalized with the brake cylin tion of braking effort is to generate Sufficient brake retarding
der Volume, So that again the final pressure depends directly 35 force on each individual car to provide as closely as practical
upon the Specific volumes and their initial pressures. uniform individual car deceleration. This requires that the
The brake System is generally configured on each car Such brake retarding force be Somewhat proportional to the actual
that the brake cylinder pressure falls within certain pre mass or weight of each car in the train. If the coefficient of
described ranges for both Service and emergency applica brake shoe friction is assumed to be generally equal for all
tions. By design, therefore, any brake application will cause 40 cars in the same train, where Velocity and wheel tempera
the control valves to produce nominally equal brake cylinder tures will be very similar, then proportioning retarding force
preSSures on all cars within the train. If all Volumes and to weight can be achieved by having an equal operative net
piston travels were exactly equal on each car and the System braking ratio on each car.
had no leaks, Such brake cylinder pressure would be gen Effective net braking ratio can be defined as the actual
erally equal for all practical purposes. The System, by 45 total brake shoe force divided by the actual weight of the car.
design, is intended to produce generally equal brake cylinder Design net braking ratio is generally considered to be the net
preSSures on each car, in response to a specific brake pipe braking ratio at 50 psi brake cylinder pressure.
reduction. However, because of nominal variations in It is not practical, nor will it usually be desirable,
Volume, piston travel, leakage, and grading, there may exist however, to brake fully loaded and empty cars in the same
a fairly wide, Somewhat random variance in the actual brake 50 train at completely equivalent net braking ratios during train
cylinder pressures throughout any given train for any give deceleration. At a given brake cylinder preSSure or Shoe
brake application. The variations in resulting brake forces, force, the effective net braking ratio of empty and loaded
including the net brake shoe force and brake retarding force, cars of the same design is inversely proportional to their
are further compounded over the variations in brake cylinder weight. This means that the empty car net braking ratio (and
preSSures. Various freight cars built at different times can 55 potential deceleration) could be four to six times higher than
have different sizes and types of brake cylinders, differing that of the fully loaded car at a given brake cylinder pressure.
mechanical linkage ratioS, and widely different mechanical One of the primary factors which limits the maximum
efficiencies. All of these factors directly effect the net brake design net braking ratio on loaded freight cars is the wheel
shoe force that is produced by any given brake cylinder temperatures which can be developed, which is controlled
preSSure on a given car. The effective coefficient of brake 60 by the braking effort and the heat dissipation capacity of the
shoe friction then determines the brake retarding force wheels on the vehicle. On empty cars the limiting factor is
generated by any given brake Shoe force on a specific car. generally the potential of Sliding wheels, as governed by the
With electro-pneumatic brakes it is possible to control the available wheel to rail rolling adhesion. Due to potential heat
actual brake cylinder pressure more precisely than with dissipation demands and train action factors, the maximum
conventional pneumatic brake Systems. However, although 65 desirable design net braking ratio on loaded 100 ton freight
it would be possible, it can be disadvantageous and unde cars having 36 inch wheels is approximately 10 percent of
Sirable to simply generate equal brake cylinder pressures on the net braking ratio. For empty cars on the other hand, the
 5,833,325
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typical historical maximum design net braking ratio (at 50 an electrical conductor or fiber optic cable, and is used to
psi brake cylinder pressure) has been approximately 30 convey information from one position on a train to other cars
percent, to prevent wheel sliding. in the train. In some embodiments this will be used to
It is usually neither necessary nor desirable to reduce the transmit a brake Signal indicative of the desired brake level
empty car net braking ratio clear down to 10 percent to to all of the cars, 37 through 40. Similarly, the train line 1
match the maximum loaded car NBR. This would greatly can be used to also Send a pre-Selected operating train net
reduce the available train brake retarding force of trains braking ratio value to all of the cars 37 through 40. As shown
having a Sufficient number of empty cars, and would further in FIG.1a, car 37 has a microprocessor 42 which can receive
increase the heat dissipation demand on the wheels of loaded control Signals and information from the train line 1. The
cars in a train consisting of mixed loaded and empty cars. microprocessor can be used to control a valve means which
To better protect against wheel Sliding on empty cars with may be one or more valves or Similar devices which control
less than ideal wheel to rail adhesion it is desirable to limit the communication of fluid pressure from a reservoir 43 to
the maximum design net braking ratio on completely empty a brake cylinder 44. Brake cylinder 44 applies a friction
cars to approximately 20 percent NBR instead of the his brake on car 37. AS to be understood, cars 38, 39, and 40 can
torical 30 percent. This would provide a highly effective 15 be comparably equipped as car 37.
protection against Sliding wheels on empty cars and also FIG. 1b is a diagrammatic representation of an electro
achieve a generally optimum compromise between keeping pneumatic brake System on-board a railway freight car Such
an effectively high capacity of braking on empty cars (to as 37. The present invention can be implemented through the
benefit the entire train deceleration and control) while bring use of a microprocessor unit MPU to which a train line wire
ing the potentially full deceleration rates on empty and 1 is connected by a branch wire 3. It is understood that this
loaded cars much closer together limiting in-train forces. embodiment shown in FIG. 1 utilizes a “hard wired’ elec
Therefore the final objective is to allow fully loaded cars trical train System in which the Signal is delivered to the
to be braked in a range of approximately 6.5 percent to 10 on-board microprocessor by way of one or more wires.
percent design NBR, and, at the same time to limit the Typically, Such wire could be an electrical wire, although
maximum NBR on empty cars to 20 percent NBR. Given 25 other embodiments could equally employ fiber optics.
these objectives, it is necessary to define the optimum way Similarly, radio transmission Signals/receivers or other com
to transition from the completely empty to the fully loaded munication means to communicate with the carborne equip
car NBR for any and all partial load conditions in between. ment could be used. Typically Such Systems, whether using
The design net braking ratio (DNBR) of a freight car is radio, electrical wire, or fiber optics would be transmitting
determined when the car is built, generally being based on information from a central location, usually in the locomo
the following formula: tive cab or other site off-board the individual freight car.
Such signal could carry a desired level of braking Signal and
Measured SHOE FORCE a signal representative of an operating NBR for the train. An
DNBR = Loaded Car Weight application electromagnet valve A, and a release electro
O
35 magnetic valve R respectively control the application and
release functions. A relay valve Such as RV, Similar to a J
DNBR = Px LXA xN XE type relay valve as manufactured by Westinghouse Air
W Brake Company, can be used in conjunction with the appli
cation (A) and release (R) valves to control Supply of
where: 40 pneumatic pressure to a brake cylinder, BC. In Some
P=pressure in the brake cylinder embodiments direct acting application and release valve
L=lever ratio mechanisms may be used, Such that a relay valve may not be
required. A Supply reservoir, SR, to which a train line brake
A=the area of the piston(s) in the brake cylinder(s) pipe, BP, is connected can also be connected to the brake
N=the number of brake cylinders 45 cylinder via the relay valve, RV. Pneumatic pressure is
E=the mechanical efficiency supplied to the reservoir, SR, via a branch pipe 5 from the
W=weight of the car train line brake pipe, BP. A one way check valve, 7, may be
It will be seen from the above equations, assuming a used to maintain the Supply reservoir, SR, charged to a
constant efficiency factor and a given car weight, the only preSSure as carried in the brake pipe, BP and prevent
variable in the formula will be the brake cylinder pressure. 50 discharge back into the BP. In addition, a brake pipe regu
Therefore, varying brake cylinder pressure changes the lating valve (not shown) may also be used in Some appli
effective or operative net braking ratio of the car. In deter cations. Application electromagnetic valve, A, and release
mining a car's design net braking ratio, by definition a electromagnetic valve, R, are controlled by a microprocessor
predetermined brake cylinder preSSure is used in the fore unit, MPU, via control wires 9 and 11 respectively. Appli
going equation. Generally a value of 50 psi is be used. 55 cation electromagnetic valve A is a normally closed, two
FIG. 1a shows a train having a locomotive 36 and a position, two way, Solenoid operated valve having a Spring
plurality of cars 37 through 40. As can be understood, freight return. While electromagnetic release valve R is a normally
trains can operate many more cars than shown, and typically open, two-position, two-way, Solenoid operated valve hav
one-hundred to two-hundred car trains are not uncommon. ing a Spring return. The inlet port of application electromag
While FIG. 1a only depicts four freight cars, it is to be 60 netic valve A is connected by a pipe 13 to Supply reservoir
understood that multiple cars of any length can be used in SR, and the outlet port of valve A is connected by a pipe 15
practicing the invention. In addition, a diagrammatic repre to the control port of a relay valve RV. The electromagnetic
Sentation of equipment on-board car 37 is shown, however application valve A is also connected to a port of the release
it is understood that Similar equipment can be placed on electromagnetic valve R. The outlet port of release electro
other cars in the train shown in FIG. 1a. 65 magnetic valve R is vented to the atmosphere. The Supply
Car 37 shows a train line wire 1 which connects all of the port of relay valve RV is connected to a pipe 17 which is
freight cars to the locomotive. This freight train line could be supplied from the Supply reservoir SR. The delivery port of
 5,833,325
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the relay valve RV is connected to a pipe 19 which com design net braking ratioS equal to the train net braking ratio,
municates with the brake cylinder BC. The relay valve RV NBR. The brake cylinder pressure is adjusted on each car
also has an exhaust port which is vented to atmosphere. A for all brake applications, Such that each car behaves as if its
preSSure to electric transducer T1 may also be used, and, if individual net braking ratio (its design net braking ratio) was
So, it may be connected through a pipe 21 to pipe 19, or may exactly the preselected value of the train net braking ratio,
be directly connected to either the brake cylinder or the relay NBR. Typically when a railway locomotive sends a desired
valve or pipe 19 or at any other convenient point. The brake level Signal, two given cars may apply the identical
transducer T1 is electrically connected to the microprocessor desired brake cylinder pressure, but because of different net
via wire 23 which could also be an optical fiber line. A braking ratios each car although identically loaded may
Similar transducer T2 may be connected to the brake pipe provide quite different levels of actual braking force, and
BP, directly on such as is shown via a pipe 25. Transducer therefore different deceleration rates may occur and Sub
T2 may also be connected at any other place in the car where Stantial in-train forces may result.
In a typical embodiment of the present application, the
the brake pipe pressure is readily available. Transducer T2 is locomotive train via the train line 1 may send an operating
electrically connected via wire 27 or optical fiber liner to net braking ratio for the train, NBR. This NBR signal
Supply a brake pipe preSSure input to the microprocessor unit 15
could be an initial value which is sent only when the train is
MPU. made up and begins to operate, or could be periodically Sent
Another input to the MPU can be a load signal such as along the train line 1. In other embodiments the net braking
shown at connection 29 where the varying car weight under ratio for the train, NBR, may be communicated to each
operating conditions may be input to signify either a specific individual car in a different manner, and cars may in fact be
weight or an empty/load condition. Spring deflective or pre-programmed to have a default value of NBR. Such
other load Sensors may be used to Supply the load Signal, 29. values may be sent to the MPU and stored via 31 or 33.
Additional Signals 31 may be input to give Specific car During operation each individual car Stores the desired
parameters as hereinafter discussed through the micropro NBR value on-board, and continues to receive normal
ceSSor unit. InputS 33 are available to Supply the micropro brake Signals Bs via line 1 with regard to the desired level
ceSSor units with variables which may be specific to the 25 of braking Sought by the locomotive engineer. In Some
locomotive or the train operating conditions. Systems this may be a desired nominal brake cylinder
When a brake application System ed for the microproces preSSure, BCP, or it may be a brake pipe preSSure reduction
Sor unit energizes the System according to its internal typical of that used in pneumatic Systems. Regardless of how
operating instructions. Wires 9 and 11 cause the respective the desired braking Signal is established, the on-board
Solenoid operators to Switch positions to either apply or microprocessor for each car then can interpret it and using
release the electro-magnetic valves. The electro-magnetic the NBR properly apply the correct individual car brake
Valve R is thus closed and the application electro-magnetic cylinder preSSure to arrive at the force based upon the train
valve A is opened to conduct brake pipe pressure from the net brake ratio, NBR. In Some instances the brake signal
compressed air Source in the Supply reservoir SR to the relay may be a percentage of handle control, Such as 100 percent
valve RV. Relay valve RV is piloted to its application or 35 for full Service, 75 percent, 35 percent, 25 percent, etc. may
release positions. Transducer T1 provides feedback infor be desirable.
mation to the microprocessor corresponding to the instan While in describing the present invention when is stated
taneous brake cylinder pressure. When the microprocessor that each individual car then controls the brake cylinder
determines that the necessary brake cylinder preSSure has preSSure in that respective car to execute the given train net
been reached, wire 9 may be de-energized to drop out the 40 braking ratio; NBR, it is understood that the microprocessor
Solenoid application magnetic valve A and thereby cause the permits an adaptability Such that the train net braking ratio,
relay valve RV to cutoff further pressurization of the brake NBR, will in many instances only be used over a certain
cylinder BC. range of operation of the brakes. Such range may typically
Similarly, when the release or reduction of the brake include the Service range of brake applications and in fact
application is desired, the microprocessor unit can 45 the microprocessor may control the individual car brake
de-energize wires 9 and 11 causing both the electro equipment to behave other than at the NBR in an emer
magnetic valves A and R to assume their normal position, gency mode, and/or for minimum brake applications, and/or
thereby causing the relay valve to vent to atmosphere other specific braking tasks. Typical characteristics that
portions of the brake cylinder pressure. The embodiments require an emergency application may dictate other than
shown in FIG. 1b can be utilized in conjunction with the 50 utilization of the NBR characteristics which are desirable
other teachings herein to control the Specific braking for the Service mode. It is also possible, however, in Some
on-board a freight car. Other similar known Controls of situations to utilize the NBR for both service and emer
Application and Release valves to Supply, lap, and release gency applications when desired.
fluid pressure can be used with this invention, including the In addition, due to the fact that mechanical efficiencies
use of a single valve. It is understood that brake rigging is 55 and friction at low force levels may vary on any given car,
attached to the brake cylinder, and may be of any Style or and in fact may vary from car to car, it may be desirable in
fashion including truck mounted or conventional. many embodiments to indicate Some minimum threshold
This invention permits a preselected desired train net level of braking which may occur before the NBR opera
braking ratio, NBR, at which the brakes on all cars in any tion is desirable. In addition, there may be other specific
such train will operate. FIG. 1b shows a braking system 60 brake functions with regard to the car having excessively
which receives on-board a freight car Vehicle a desired net high loads, very low loads, etc. that may dictate other than
train braking ratio Signal and a braking Signal and converts a pure NBR operation for certain ranges within the enve
the braking Signal into the actual desired brake cylinder lope of operation. The utilization of the microprocessor in a
preSSure for Such car as if it had the operating Train Net preferred embodiment of this invention makes it easy and
Braking Ratio. While individual cars may have design net 65 highly desirable to provide overlays of other brake
braking ratioS that differ from car to car in a given train, this operations, Such as grade and emergency controls which can
invention permits the whole train to behave as if all cars had further enhance the performance of the Overall train braking.
 5,833,325
10
FIG. 2 illustrates a preferred methodology for translating predetermined percentage (approximately 42.2 percent) of
or blending the higher design net braking ratio on empty cars the difference between 8 psi and the full service pressure.
to the lower design net braking ratio of fully loaded cars, From 43 degrees to approximately 58 degrees of handle
through the possible range of car loadings. The two NBR rotation, the brake cylinder preSSure for the train, BCP,
curves on this graph represent that practical minimum increases linearly to the maximum full Service pressure.
design NBR which might be desired, such as 6.5 percent on Desired full service brake cylinder pressure varies with
a fully loaded car weight on 286,000 pounds, as well as the initial brake pipe pressure and can be generally calculated by
normally accepted maximum NBR of 10 percent on 263,000 the following equation:
pounds. The net Shoe forces required to obtain these two
design NBRs are 18,590 pounds and 26,300 pounds respec 1O BCP =0.77 BP-3.8 (using gauge pressure in psi)
tively. These net Shoe forces are allowed to be applied as the
car weight becomes lighter, until the net braking ratioS When the brake valve handle is moved beyond the full
increase to 20 percent or the maximum desired level to Service Zone to emergency, the desired emergency brake
protect against wheel slide. This occurs at a transition car cylinder pressure, BCP, is indicated by the following
weight of 131,500 pounds for the higher net shoe force and 15
equation:
at 92,950 pounds for the lower net shoe force. BCP=0.857BP (gauge pressures)
AS the car weights are further reduced, down to any
completely empty weight (generally between 43 and 63 These equations derive to generally match the Standard
thousand pounds) the net shoe force (NSF) is reduced equalization preSSures produced by the conventional pneu
linearly as required to keep a constant 20 percent effect net matic brake System for full Service and emergency brake
braking ratio. This meets the NBR definition: applications, although the conventional System is Subject to
NBRNSFW Some variation.
In order to provide the desired uniformity of braking
throughout the train, it is necessary to compensate for the
25 widely varied design net braking ratio of all the individual
where W=actual car weight cars that may be involved. This is achieved in the present
In this case, for light cars the net shoe force, NSF=0.2xW. invention by making use of certain values that are prede
The net braking ratios illustrated on FIG. 2 represent, by termined and may be semi-permanently Stored in memory of
definition, the design net braking ratioS for the cars, or the the electronic car brake control on each individual freight
net braking ratio at 50 psi brake cylinder pressure. With the car. For each group of new cars built to a common design,
provisions of the present invention it is possible with an the AAR requires that car builders conduct brake Shoe force
electro-pneumatic brake System to allow the railroad or the measurement tests on a certain number of individual cars.
individual train operator to preselect an effective or equiva This is to assure that the cars meet or fall within the
lent loaded car design net braking ratio at which the train is prescribed net braking ratio range. In conducting Such tests
to be operated. This can be set on the locomotive brake 35 it is common practice to apply various predetermined and
control microprocessor at any desired decimal value, Such as closely controlled brake cylinder pressures to the car brake
between 0.065 and 0.100. In essence, this option will cause cylinders and to measure the total net or actual brake Shoe
the entire train, including each of the individual freight cars force thereby produced on all eight wheels. Such measure
to be braked as if their individual loaded design net braking ment may be obtained using calibrated, force measuring
ratio were all exactly the pre-selected value (NBR). 40 dynamometer brake shoes.
Regardless of the preselected train NBR, the NBR can also FIG. 4 shows a typical pattern for the relationship
be adjusted for car loading as illustrated by the upper and between brake cylinder preSSure and net shoe force for a
lower limits on FIG. 2. In addition the effective initial or given freight car. The line through the origin represents the
operating brake pipe pressures can be set at the regulating theoretical or “gross' shoe force. The offset line represents
Valve on the locomotive brake Stand to any pressure, Such as 45 the actual or “net” brake shoe force. The theoretical neglects
for example between 70 psia and 110 psi. the friction loss due to the brake cylinder seals and fulcrum
When a conventional 26C pneumatic locomotive brake joints inherent in the mechanical Systems, as well as the
Valve handle is rotated to apply the train brakes, a mechani resistive force of the piston return Spring. Both the theoreti
cal cam and cam follower act against the regulating valve cal and the actual relationships are typically generally linear
Spring to control the reduction of equalizing reservoir 50 functions of brake cylinder pressure, as illustrated. The
preSSure, and consequently the brake pipe preSSure, BP. The brake rigging mechanical efficiency would be obtained by
profile on the brake valve cam follows the general pattern of dividing the actual shoe force by the theoretical shoe force
the curves shown on FIG. 3 with regard to the brake valve at any given brake cylinder pressure.
handle position and linear cam travel. The general linear equations describing the relationship of
With electro-pneumatic braking it is desirable to generally 55 the net Shoe force and the brake cylinder preSSures for any
match the degree of Service application produced by the car can be calculated as follows:
conventional pneumatic brake System, to which train opera
tors have become accustomed. Therefore, for the electro
pneumatic brake of the present invention, FIG.3 represents
F -F 2
the train brake cylinder preSSure demanded throughout the 60
N-Fs (P-0---- (slope) (2)
Service range of rotation of the brake valve handle, for three
distinct initial brake pipe operating preSSures. The minimum
reduction Zone, from approximately 8 degrees to 15.6 degree P=(Fv. M+a (3)
handle position, is interpreted to call for 8 psi train brake where:
cylinder pressure, BCP, regardless of the initial brake pipe 65
pressure BP. From 15.6 to 43 degree rotation, the brake Fy=net (actual) shoe force (measured in pounds)
cylinder pressure, BCP, increases linearly from 8 psi to a P=brake cylinder pressure (psi)
 5,833,325
11 12
N=slope preSSure for the Specific car BCP is calculated based upon
a=brake cylinder pressure (P) at Zero actual force (offset the net shoe force for the car, F and the stored values N and
or intercept) A previously discussed with regard to FIG. 4.
and FIG. 6 shows an alternate flow diagram for the calculation
(F, P) and (F, P) are force and pressure points or of net shoe force and BCP. In FIG. 6 the net shoe force for
corresponding values for force and preSSure at any the Nth car F is calculated based upon the train net braking
given points on the graph. ratio and the train brake cylinder pressure Signals. In addi
Using these equations, it is possible to calculate either the tion the car load capacity is utilized. The car parameters as
brake cylinder preSSure required to produce any given net in the other instances can also be programmed into the MPU
shoe force, or to calculate the net Shoe force that would be by the car parameters 31. The Shoe force is then compared
expected for any given brake cylinder pressure. In order to to a function of the weight. As shown, the value of 20% is
utilized in 62. If the net shoe force as calculated for the Nth
define the Specific equations for any car, it is necessary to car is greater than 20%, then the calculation for net Shoe
pre-determine values for a and N. These values may be force is redone in block 64. The revised F calculation from
obtained either from actual shoe force test results or by block 64 or the initial F from block 62 is then used in block
closely estimating these values using test results from iden 15 65 to calculate the required brake cylinder pressure for the
tical cars or cars having very similar brake arrangements. In Nth car, BCP.
Some instances it may be desirable to merely enter default The method depicted in the flow chart of FIG. 5 propor
values which closely represent the cars which will be tions the BCP on cars under the transition weight even for
operating on the train. brake applications calling for less than 50 psi BCP. The
Specific values for the a and N are entered and may be method of FIG. 6, on the other hand, only limits empty car
Stored Semi-permanently in protected memory on each BCP if the requested BCP would produce an NBR exceeding
freight car microprocessor that is equipped with electro O2O.
pneumatic brake equipment of the present invention. These While certain embodiments of the invention have been
may be input, such as at terminals 31 on FIG. 1b. shown in the attached figures and discussed in this descrip
Referring now to FIG. 5 is shown an algorithm of the 25 tion it will apparent to those skilled in the art that other
calculation which can be done on-board the railway vehicle embodiments are equally included within the Scope of this
invention. This invention covers those other embodiments as
to determine the brake cylinder pressure, BCP of the Nth. included within the Scope of the following claims.
This calculation is done by receiving the nominal brake I claim:
cylinder pressure train command Signal, BCP. AS will be 1. Railway freight brake apparatus for operation on-board
understood the calculations in comparison shown in FIG. 5 a rail vehicle in a train, Such vehicle having a friction brake
will most often be done in a microprocessor unit Such as actuated by a pneumatic brake cylinder and having a reser
MPU shown in FIG. 1, although other means of performing voir as a storage Source of pressurized fluid, Such apparatus
these calculations can also be utilized consistent with this comprising:
invention. AS previously described the net braking ratio of (a) at least one valve to control the pressurization of Such
the train, NBR, can be periodically transmitted along the 35
brake cylinder from Such reservoir;
train line wire 1 of FIG. 1b or a default value can be
preselected and stored on board each freight car. Whatever (b) means for receiving a brake signal indicative of a
manner the microprocessor unit has the ability to receive the desired braking level of Such train and for receiving a
net braking ratio for the train, NBR for the necessary train net braking ratio;
calculations. ASSuming that the NBR has been periodically 40 (c) a processor for calculating a brake cylinder pressure
transmitted or encoded into the brake Signal on the train line from Said brake Signal and Said train net braking ratio
wire at block 51 both the brake cylinder pressure of the train to produce a net shoe force as if Such vehicle had a
and the train net brake ratio available and received in block design netbraking ratio generally equal to Said train net
51. These values are then utilized in the calculation of the brake ratio,
empty load transition weight, W, as is shown in block 52. 45 (d) said processor controlling said valve to Supply Such
After the transition weight W is calculated, in block 53 the brake cylinder with pneumatic fluid at Said calculated
actual weight of the Nth car, W is obtained. This can be brake cylinder preSSure over a portion of a range of
done in a number of means on-board the car and input to the braking of Such vehicle; and
multiprocessor unit of FIG. 1b via one of the car parameter (e) wherein Said range of braking of Such vehicle includes
inputs 31. The value of the car weight may also be obtained 50 a Service application of braking and excludes an emer
based upon pre-existing known load conditions for each car gency brake application as determined from Said brake
in the train, from a train consist list. In block 54 the car Signal.
weight of the Nth car, W is compared to the transition 2. The railway freight brake apparatus of claim 1 wherein
weight W. If the car weight W is less than the transition Said range of braking excludes a predetermined minimum
weight the desired braking force of the Nth car F is 55 braking level.
calculated as shown in block 56 based upon the brake 3. The railway freight brake apparatus of claim 1 wherein
cylinder pressure Signal, BCP. If the comparison in block Said range of braking excludes braking when Such vehicle is
54 indicates that the weight of the car W is equal to or descending a grade as determined from Said brake Signal.
greater than the transition weight W, then the calculation of 4. A railway freight brake apparatus for operation of a
the net shoe force F is calculated in block 55. The calcu 60 train having a locomotive and freight vehicles attached to
lation in block 55 calculates the net shoe force, F based Such locomotive, each of Such vehicles having a friction
upon the Signals it has received corresponding to the train brake actuated by a pneumatic brake cylinder and having a
brake cylinder pressure BC and the train net braking ratio reservoir as a Storage Source of pressurized fluid, Such
NBR. In addition the GRL of the specific car is utilized in apparatus comprising:
the calculation of the force requirement for that given 65 (a) means on Such locomotive for transmitting a brake
Specific Nth car. The calculated net Shoe force F is then Signal indicative of a desired braking level of Such
transmitted to block 57 wherein the necessary brake cylinder train;
 5,833,325
13 14
(b) a plurality of Such vehicles having means for receiving braking ratio, and as if all of the vehicle brakes had the
Said brake Signal indicative of a desired braking level of Same design net braking ratio and generally equal to
Such train and for receiving a train net braking ratio, Said train net braking ratio; and
(c) Said plurality of vehicles each having at least one valve (f) wherein said range of braking of Such train includes a
to control the pressurization of the respective ones of 5
Service application and excludes an emergency appli
Such brake cylinder and Such reservoir; cation.
(d) said plurality of vehicles each having a processor for 5. The railway freight braking apparatus of claim 4
calculating a brake cylinder preSSure from Said brake wherein Said range of braking excludes a predetermined
Signal and Said train net braking ratio for each vehicle; minimum braking level.
(e) said processors being effective to control said respec 6. The railway freight braking apparatus of claim 4
tive valves to Supply respective Such brake cylinders wherein Said range of braking excludes braking when Such
with pressurized fluid at Said calculated brake cylinder vehicle is descending a grade as determined from Said brake
preSSure over a portion of a range of vehicle braking to Signal.
produce a net Shoe force as if each vehicle had a design
net braking ratio Substantially equal to Said train net