Air brake control valve with combined graduated and direct release

A control valve is mounted to a pipe bracket which also includes a manual release valve and an emergency vent valve. The control valve operates with a single reservoir to perform service and emergency brake applications. A pair of interrelated pistons responsive to brake cylinder pressure, brake pipe pressure and control volume pressure operate a supply valve, a quick service valve end exhaust valve to maintain a fixed ratio of brake cylinder pressure to brake pipe pressure reduction. Quick service volume is continuously vented and appropriate valving is provided to allow plural sequential quick service operations. Structures provided to operate the piston stack so as to initially allow graduated brake release and subsequent direct brake release over the brake releasing range. An accelerated emergency release mechanism is also provided. The supply reservoir is only charged during the direct release mode. Brake cylinder pressure is exhausted to brake pipe following an emergency application and is exhausted to atmosphere after a service application.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates generally to brake control values for 
operating a vehicles air brake system in response to brake pipe pressure 
and more specifically to an improved control valve. 
Brake control valve systems for vehicles having air brakes generally 
include a brake control valve responsive to brake pipe pressure in a brake 
pipe to operate the brakes of a vehicle from a reservoir. For reduction of 
brake pipe pressure, the brakes are proportionally applied. For an 
increase in brake pipe pressure, the brakes may be released totally, known 
as direct release or gradually, known as graduated release. In AAR 
systems, the brake control valves include a service section and emergency 
section connected to a pipe bracket which are responsive respectfully to a 
service rate of reduction and an emergency rate of reduction to apply the 
brakes appropriately. Each section includes a separate diaphragm 
responsive to brake pipe pressure on one side and a reference pressure on 
the other. Not only do the brake control valve differentiate between a 
service and an emergency application, but they also must react in a 
specific amount of time to apply the brakes and to propagate the signal 
through the brake system to other cars. 
The present control valves, as exemplified by the DB-60 from New York Air 
Brake or the ABDW from Wabco, include service (auxiliary) and emergency 
reservoirs with the service section applying the fluid from the service 
reservoir during a service brake application and the service and emergency 
sections providing service and emergency reservoir pressure during an 
emergency brake application. The service and emergency sections propagate 
service and emergency signals respectively. A release valve is associated 
with the service section and a retainer valve is also provided. Both of 
these control valves are a direct release system. 
Historically and in non-AAR countries, the release system is considered a 
graduated release. This is where the brakes can be partially released no 
different than the brakes being gradually applied. Systems have been 
designed which have the ability to convert between a graduated and a 
direct release. Similar systems exist wherein combination with a simpler 
control valve, an emergency vent valve has been provided which senses an 
emergency braking condition on the brake pipe and propagates the signal by 
locally venting the brake pipe. 
For certain brake applications, there is not a need for the sophisticated 
braking conditions found in the DB-60 and like control valves. Also, with 
the increased use of electropneumatic valve systems, there is a need for a 
simpler redundant pneumatic valve. 
Thus, it is an object of the present invention to provide a simpler control 
valve. 
Another object of the present invention is to provide a simpler control 
valve to be used with electro-pneumatic systems. 
Still a further object of the present invention is to provide a control 
valve which combines graduated release with direct release over the 
release range. 
Another object of the present invention is to provide a valve which is 
capable of plural sequential preliminary quick service. 
A further object of the present invention is to provide a control which 
allows for minor adjustments of brake cylinder pressure without quick 
service. 
An even further object of the present invention is to provide a control 
valve which has a graduated release during the initial period and 
terminating with a direct release or release ensuring. 
Another object of the present invention is to provide a control valve which 
inhibits accelerated release transmission until the valve is in its direct 
release mode. 
These and other objects are achieved by a brake control valve system having 
a pipe bracket with a single section control valve thereon working with a 
single reservoir, an emergency vent valve thereon and a manual release 
valve on the control valve. The single portion valve includes a first 
piston subject to brake pressure on one side, quick braking valve for 
connecting brake pipe pressure to a quick braking volume and a supply 
valve for connecting the reservoir to the brake cylinder and an exhaust 
valve for connecting brake cylinder to atmosphere. An operator mechanism 
controls the quick braking and supply valves in response to the position 
of the first piston so as to open the quick braking valve only when the 
supply valve is open. The supply valve may be opened without opening the 
quick braking valve. This is produced by the use of poppet valves and loss 
motion between the elements. 
A choke is provided for continuously venting the quick braking volume to 
the atmosphere. A limiting valve is provided for disconnecting the quick 
braking valve from the quick braking volume when the brake cylinder 
pressure is 15 greater than the brake pipe pressure. This prevents the 
brake pipe from being vented through the first choke in a release after an 
emergency braking. An in-shot valve is provided between the reservoir and 
the brake cylinder. 
In addition to the first piston which is subject to brake pressure on one 
side, a second coaxial piston is provided which is responsive to brake 
cylinder pressure on one side for controlling, with the first piston, the 
supply valve and exhaust valve to maintain a fixed ratio of brake cylinder 
pressure to brake pipe pressure reduction. Appropriate loss motion is 
provided between the first and second pistons as well as the second piston 
and the supply and quick braking valves. This allows supplying of the 
brake cylinder with the reservoir pressure by opening supply valve without 
opening the quick braking valve to maintain a given value in the brake 
cylinder. 
An exhaust valve is provided for connecting the brake cylinder to 
atmosphere when opened by the first piston in response to an increase in 
brake pipe pressure which indicates a release. A control volume is 
provided preferably in the pipe bracket and the first piston is subject to 
control volume on a second side opposite the first side which has the 
brake pipe pressure. A charging valve connects the brake pipe to the 
reservoir and to the control volume when open. This valve permits charging 
of the reservoir and the control volume. The charging valve also controls 
the first piston to operate the exhaust valve in a graduated release mode 
for initial ranges of increased brake pipe pressure and the charging 
valves open for a full release of the brakes for a final range of 
increased brake pipe pressure in a direct release made. The opening of the 
charging valve interconnects both sides of the first piston to ensure that 
it goes into the fully released mode and also provides an increase in 
brake pipe pressure from the supply reservoir and the control volume to 
increase the propagation of the direct release down the brake pipe. 
An emergency relay valve connects the reservoir to the supply valve when 
the brake cylinder pressure is below a first value compared to the control 
volume pressure. 
An emergency accelerator release mechanism is also provided. It includes a 
dissipation valve which connects brake pipe and the brake cylinder when 
the brake cylinder pressure is a first value greater than the brake pipe 
pressure. An accelerator release valve connects the dissipation valve to 
the brake pipe and is opened when the brake pipe pressure is above a 
minimum value. Upon release or recharging after an emergency application, 
first the accelerator release valve is opened, providing brake pipe on one 
side of the dissipation valve. Since the brake cylinder has a greater 
pressure than the brake pipe, the dissipation valve is opened and brake 
cylinder is bled into the brake pipe and thereby increases the pressure in 
the brake pipe. This propagates the brake pipe release signal. It should 
be noted that the brake cylinder exhaust valve has not opened yet. As the 
brake pipe pressure builds up, the brake cylinder exhaust valve opens 
after the dissipation valve closes. This exhausts the remainder of brake 
cylinder pressure to atmosphere instead of the brake pipe. 
With respect to the overall system, the control volume and the quick 
braking volume are preferably in the pipe bracket. The control valve 
includes the first and second pistons, supply valve, quick braking valve, 
brake cylinder exhaust valve, dissipation valve, emergency accelerated 
release valve, emergency relay valve and in-shot valve. The emergency vent 
valve on the pipe bracket is responsive to the emergency rate of decrease 
of pressure, to vent the brake pipe at the pipe bracket to atmosphere to 
initiate and propagate emergency braking. The emergency vent valve does 
not provide any direct control of the brake cylinder. This is performed by 
the control valve. A manual release valve is mounted to the control valve 
for venting both the cylinder and the reservoir when manually actuated. 
The release valve completely vents the brake cylinder in response to 
manual actuation and vents the reservoir only during manual actuation. 
Other objects, advantages and novel features of the present invention will 
become apparent from the following detailed description of the invention 
when considered in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
A vehicle braking system is shown in FIG. 1 as including a control valve 
portion 10 connected to a pipe bracket 30. An emergency vent valve 20 is 
also mounted to the pipe bracket 30. A manual release valve 40, for 
example in a DB-60, is connected to the control valve piston 10. Brake 
pipe 50 is connected to the pipe bracket 30 through a dirt collector and 
cut-out cock 52. A single supply reservoir, (SR)54 is connected to the 
pipe bracket 30 as is the brake cylinder (BC) or truck mounted brake 58 
through an empty load valve (E/L)56. When not needed, the empty load valve 
56 can be deleted. The control valve 10 performs charging, service and 
emergency applications and release functions as well as quick service 
braking and accelerated release in emergency. The emergency vent valve 20 
provides only emergency initiation and propagation and no braking 
functions. Thus, it senses an emergency application and connects the brake 
pipe through the pipe bracket 30 to atmosphere to quickly draw down the 
brake pipe 50. The release valve 40 provides manual release of the brake 
cylinder and exhausts the supply reservoir when manually actuated. A 
single supply reservoir 54 may be, for example, an 8000 cubic inch 
reservoir and the only reservoir connected to the pipe bracket 30. 
It should be noted that the control valve 10, emergency vent valve 20 and 
the release valve 40 are shown connected on a single side of a pipe 
bracket 30, this is but one embodiment. This single sided mounting is 
preferable for specific car construction. The principles of the present 
invention include the unique control valve 10 mounted to any style pipe 
bracket with the emergency vent valve on the other side. Preferably, the 
control volume and the quick service volume are located in the pipe 
bracket 30. This reduces the weight and overall size of the control valve 
portion 10. 
After describing the specific elements of the valve, the operation of 
various elements will be described. 
The valve in its released and charging position is illustrated in FIG. 2. A 
main or a control piston. 102 lies in a chamber having brake pipe pressure 
in an upper chamber 101 and control volume pressure in lower chamber 103. 
A pair of operators 104 and 105 extend from the control piston 102 and are 
received in guides 106 and 107 respectfully. Seal 108, for example, 
pressurized K-rings, seals the chambers 101 and 103 and allows the 
operators 104 and 105 to sealably slide relative to the housing 100. An 
extension 105A of operator 105 controls the brake cylinder exhaust valve 
166. Passage 110 connects the brake pipe at port BP IN to chamber 101 
above the control piston 102. A control piston return spring 109 biases 
the control piston 102 down. The spring 109 may be, for example, a 
one-pound spring. 
A relay piston 112 is subject to brake cylinder pressure in an upper 
chamber 111 and atmosphere in lower chamber 113. A pair of operators 114 
and 115 extend from the relay piston 112 and are received in slides 116 
and 117 respectively. Seals 108, for example, O-rings, are provided for 
the operators 114 and 115. A gap or loss motion is provided between the 
upper operator 104 of the control piston 102 and the lower operator 115 of 
the relay piston 112. The brake cylinder port BC is connected to the upper 
chamber 111 of the relay piston 112 through passage 120 and along the 
outside of the upper operator 114. A release bias spring 119, for example 
5 lbs., with cage is slidably carried by operator 115 and cage stop 118. 
The release spring 119 has no affect on the supply valve 123 and only 
comes into use when compressed during a release, illustrated in FIG. 5, to 
bias the piston stack 102, 112 up. 
An extension 114A of operator 114 of the relay piston 112 lies in a bore 
121 which terminates with a supply valve seat 122. The supply valve 123 
rests on the supply valve seat 122 and controls the communication of the 
service reservoir SR to the brake cylinder BC through bore 121 and passage 
120. The separation from the upper operator extension 114A and the bore 
121 defines a supply choke or restriction which may be for example 
equivalent to a 0.125 inch diameter bore. The supply valve 123 is bias 
closed by a spring 124 having a valve for example of half of a pound. 
The piston stack 102, 112 compares brake pipe and brake cylinder pressure 
in the top chambers 101 and 111 respectively, to the control volume 
pressure in chamber 103 and operates the brake cylinder supply valve 123 
and the brake cylinder exhaust valve 166 to control the pressure in the 
brake cylinder at a fixed ratio to a decrease in pressure in the brake 
pipe. For example, to reach a 2.5:1 ratio of brake cylinder pressure to 
brake pipe pressure reduction, the area of the piston diaphragm 102 can 
be, for example, 12 square inches and the area of piston/diaphragm 112 
could be 4.8 square inches. Thus, for each pound of decrease of brake pipe 
pressure in chamber 102, the brake cylinder pressure would have to 
increase by 21/2 pounds in order to bring the stack into equilibrium or 
lap. Any variation from this ratio will cause either the supply valve 123 
to open to provide greater pressure to the brake cylinder, or the exhaust 
valve 166 to remove pressure from the brake cylinder. 
In previous brake control or triple valves, the brake pipe pressure was 
compared to the supply reservoir, auxiliary reservoir or control reservoir 
which was supplying the brake cylinder. When these two pressures matched, 
the brake cylinder pressure was fixed. Since the brake cylinder volume is 
small compared to these reservoir's volume, changes in the brake cylinder 
volume were not taken into account. In use, the wheels, brake shoes and 
other elements between the brake cylinder and the wheel wear. This wear 
will result in a change of the volume of the brake cylinder. The 
equalization system of the prior control valves would not accommodate for 
this increase in volume of the brake cylinder. Thus, the brake cylinder 
pressure or desired braking cannot be assured. The present system using a 
relay system compares the brake cylinder pressure to the brake pipe 
pressure to provide a fixed ratio of decrease of brake pipe pressure to 
brake cylinder pressure. Thus, the relay system would accommodate for any 
change in the volume of the brake cylinder due to wear of the elements. 
An operator 125 extends from the supply valve 123 and rides in bore 126 
which terminates in a valve seat 127. A quick braking or quick service 
valve 128 mates with the valve seat 127 to connect the brake pipe port BP 
to bore 126 when opened. A spring 129, for example half of a pound, biases 
the quick services valve closed. A seal, for example O-ring allows the 
operator 125 to sealably slide within the bore 126 and isolate the chamber 
in which the supply valve 123 operates from the chamber in which the quick 
service valve 128 operates. Bore 126 is connected to the quick braking or 
quick service volume QS VOL via passages 131 and 132. A restriction 133 in 
passage 134 connects the quick service volume and passage 132 to exhaust 
through a quick service exhaust port QS EX. The annular space between the 
service valve operator 125 and bore 126 defines the quickest service choke 
and may be, for example, equivalent to a 0.062 inch diameter bore. 
It should be noted that there is a lost motion between the operator end 
114A of the relay piston 112 and the supply valve 123 and lost motion 
between the operator 125 of the supply valve 123 and the quick service 
valve 128. The lost motion between the supply valve 123 and the quick 
service valve 128 allows the supply valve to be opened independent of the 
quick service valve to maintain a desired pressure in the brake cylinder 
without actuating quick service. Also, it should be noted that the quick 
service volume QS VOL is continuously connected to the atmosphere through 
continuous quick service choke 133. Thus the quick service volume is 
capable of quick service operation for plural sequential brake 
applications. 
A quick service limiting valve 136 interacts with valve seat 135 on passage 
132 to close off the connection of the brake pipe to the quick service 
volume QS VOL and the exhaust QS EX when the quick service valve 128 is 
opened. The limiting valve 136 has brake pipe pressure on the top and 
brake cylinder pressure via passage 137, chamber 111 and passage 120. 
Seals 138, for example, pressurized K-rings, are provided for the limiting 
valve 126. When the quick service valve 128 is opened, the brake pipe 
pressure is generally higher than the brake cylinder pressure and the 
limiting valve 136 is opened. In emergency application and recharging 
after an emergency application, the brake pipe pressure is less than the 
brake pipe pressure, thus the limiting valve 136 is closed. The limiting 
valve 136 remains closed until the brake pipe pressure is higher than that 
of brake cylinder. This prevents the brake pipe from being bleed down to 
exhaust through choke 133 after emergency application until the brake pipe 
has reached a desired level. 
An in-shot 139, having atmosphere in a chamber above it and brake cylinder 
pressure in a chamber below it supplied via passage 140 to chamber 111, 
forms a variable restriction between passages 141 and 142 connected to the 
supply valve 123. An in-shot spring 143 for example 5 pounds, biases the 
in-shot 139 to its unrestricted free flow position. The spring is 
calibrated so as to provide unrestricted flow until the brake cylinder 
pressure exceeds approximately 15 PSI. When the brake pressure exceeds the 
bias of spring 143, the in-shot 139 will move up to further restrict the 
flow to the brake cylinder through the supply valve 123. The restriction 
varies from the equivalent of a 0,125 inch diameter bore to a 0,062 inch 
diameter bore. 
An emergency relay piston 144 is responsive to brake cylinder pressure in 
an upper chamber 145 and control volume pressure in a lower chamber 146 
via passage 147. An operator 148 engages the emergency relay piston 144 
and lies in bore 147 which has a valve seat 150 at the end thereof. An 
emergency relay valve 151 is normally biased closed against the valve seat 
150 by spring 152. Passage 153 connects the supply reservoir SR to the 
valve seat 150. Seals 154, for example K-rings and O-rings, isolate bore 
149, chamber 145 and chamber 146 from each other. The emergency relay 
piston 144 compares brake cylinder pressure to control volume pressure and 
attempts to maintain it at a fixed ratio. For example, the ratio may be 
that the brake cylinders is 85% of the control volume pressure. As shown, 
the ratio is determined by spring 152, but can also be determined by the 
ratio of the top and bottom surface of the emergency relay piston 144 
alone or in combination with spring 152. Once the brake cylinders is 85% 
of the control volume, the emergency relay valve 151 is closed cutting off 
the supply reservoir from its serial connection through the supply valve 
123 to the brake cylinder BC. 
Since the present system is a relay system for controlling the supply valve 
123 and the pressure in the brake cylinder, the emergency relay piston 144 
and emergency relay valve 151 permit the present system to meet the Power 
Brake Law requirement that brake cylinder pressure be 15-20% higher than 
service brake cylinder pressure. Referring to FIG. 6, the brake pipe and 
supply reservoir are initially charged to 90 psi. A full service brake 
cylinder pressure is 65 psi. Thus, to satisfy the Power Brake Law for the 
emergency brake cylinder pressure, the cylinder brake pressure must be 
between 74.5 and 78 psi. The chart indicates that the emergency brake 
cylinder pressure is 75 psi. Using the ratio 85% of the control reservoir, 
90 psi yields a pressure of 76.5 psi which is between the 74.5 and 78 psi 
Power Brake Law requirements. Thus, the emergency relay valve 151 is open 
for service application and only closes in an emergency situation when the 
brake cylinder is 85% of the supply reservoir. By using an emergency relay 
piston and valve, the brake cylinder can be resupplied in an emergency 
application when the brake cylinder pressure leaks down. The emergency 
piston 144 and the emergency valve 151 are not capable of bailing off the 
increase of brake cylinder pressure. 
A charging valve 155 has supply reservoir pressure in chamber 156 on the 
left side and brake pipe pressure in chamber 157 on its right side. A 
valve seat 158 is connected to passage 153 through charging and stability 
choke 159. The choke 159 may have a diameter of 0.050 inches, for example. 
Pressure spring 160 biases the charging valve 155 open when the brake pipe 
is within or greater than 0.5 psi of the supply reservoir pressure. A 
control volume check valve 161 is operatively connected to the charging 
valve 155 and interconnects the supply reservoir passage 153 to the 
control volume passage 147 through valve seat 162. The clearance between 
operator 164 and the bore of valve seat 162 defines a control volume 
charging choke and may be, for example, equivalent to a 0.020 inch 
diameter bore. A check valve spring 163 biases the check valve 161 closed. 
It should be noted that opening of the charging valve 155 and the control 
volume check valve 161 connects the supply reservoir and the control 
volume to brake pipe via the brake pipe chamber 101 of the control piston 
102. This allows charging of the supply reservoir and control volume from 
the brake pipe when the brake pipe pressure is greater than the supply 
reservoir pressure, and charging the brake pipe to accelerate release from 
the supply reservoir when the supply reservoir pressure is slightly 
greater than the brake pipe pressure. Similarly, these open valves 
interconnect the top chamber 101 and the bottom chamber 103 of the control 
piston 102. This is important during the release ensuring portion of the 
release range to convert from a graduated release to a full release 
function or mode. 
The brake cylinder port is connected via passage 165 to an exhaust valve 
166. A bore 167 having the exhaust seat 168 thereon interconnects passage 
165 and exhaust passage 169 to atmosphere. A spring 170, for example a 
half of a pound, biases the exhaust valve 166 closed. The extension 105A 
of operator 105 lies in bore 167 and defines therewith the brake cylinder 
exhaust choke. The clearance may be for example, equivalent to a 0.094 
inch diameter bore. When the brake cylinder exhaust valve, 160 is opened, 
it exhausts the brake cylinder and thereby releases the brakes. There is 
lost motion between the operator 105 of the control piston 102 and the 
exhaust valve 166. 
An accelerated release valve 171 interconnects the brake pipe port BP IN 
and its passage 110 to passage 172. Spring 173 for example 2.5 pounds, 
biases the accelerated release valve 171 closed. A dissipation valve 174 
connects passage 172 to passage 165 through passage 176 when it is open or 
off valve seat 175. Spring 177, for example one pound biases, the 
dissipation valve 174 closed. When the accelerator release valve 171 is 
opened for a given value of brake pipe pressure, the dissipation valve 174 
has brake pipe pressure on the top and brake cylinder pressure on the 
bottom. When the brake cylinder pressure exceeds the brake pipe pressure 
by a given value, the dissipation valve 174 will open increasing the 
pressure in the brake pipe using the brake cylinder pressure. This 
operation provides an acceleration of the release after an emergency 
application, since it is the only anticipated condition where the brake 
cylinder pressure would exceed the brake pipe pressure. 
RELEASE AND CHARGING 
The control valve 10 in its release and charging position is illustrated in 
FIG. 2. Since there is no pressure in the control volume or the brake 
pipe, chambers 101 and 103 are at atmosphere and the control piston 102 is 
held in a lowered position by spring 109. This opens the exhaust valve 166 
which connects the brake cylinder to exhaust. Control piston 102 in its 
lowered position is also displaced from relay piston 112. The spring 119 
and its cage rests on stop 118 and the spring is not compressed. Since 
supply valve 123 is closed, the quick service valve 128 is also closed by 
spring 129. The in-shot 138 is in its unrestricted flow position by spring 
143 and the emergency relay valve 151 is closed by spring 152. As long as 
the brake pipe and the supply reservoir are both at atmosphere, the 
charging valve 155 and the control volume check 161 are opened by spring 
160. Emergency accelerated release valve 171 is closed by spring 173 as is 
dissipation valve 174 by spring 177. 
As the brake pipe charges, the control valve 10 is charged through open 
charging choke 159 to fill the supply reservoir and the control volume. 
Once the brake pipe pressure exceeds for example 10 PSI, accelerator 
release valve 171 opens providing a brake pipe pressure in passage 172 to 
the dissipation valve 174. Since the brake cylinder has no pressure, the 
dissipation valve 174 is closed. The supply reservoir is charged through 
supply reservoir charging stability choke 159 and the control volume is 
charged through control volume choke about operator 164. The charging 
valve spring 160 provides an open bias of nominally a half of a PSI. The 
charging choke 159 prevents unintended applications of brakes. Once the 
system is fully charged, the elements remained in the position shown in 
FIG. 2. Since the charging valve 155 and the control volume check valve 
161 are opened, both chambers 101 and 103 of the control diaphragm 102 are 
interconnected and therefore the spring 109 keeps the control diaphragm 
the piston 102 in its lower position. 
SERVICE APPLICATION 
In a fully charged system, brake pipe reduction must exceed the capacity of 
the charging valve stability choke 159 to create a sufficient differential 
(nominally about half PSI) between the supply reservoir SR and the brake 
pipe BP. The charging stability choke 159 provides stability against 
unintended application due to minor variation in brake pipe pressure. 
Reference is made to FIG. 3. When a sustained reduction of brake pipe 
pressure exceeds 1 PSI per 1.8 seconds, the charging valve 155 closes 
against seat 158 disconnecting the brake pipe from the control volume and 
the supply reservoir. Further reduction of the brake pipe will cause the 
higher pressure in the control volume in chamber 103 below control piston 
102 to move the control piston 102 upward engaging the relay piston 112 
and closing brake cylinder exhaust valve 166 on seat 168. This allows the 
brake cylinder to be charged from the supply reservoir. At nominally 3/4's 
PSI differential and further upward movement of control piston 102, the 
relay piston 112 will first open the supply valve 123 and then the quick 
service valve 128. The open quick service valve 128 will locally and 
quickly decrease brake pipe for example one-to-one and one-half PSI 
through the quick service choke formed between operator 125 and bore 126 
into the quick service volume via passages 131 and 132. This provides 
accelerated service application. 
During initial application, the relay piston 112 must overcome the force of 
the supply reservoir pressure on top of the supply valve 123. As it does, 
the relay piston 112 jumps through the sudden equalization of pressure 
above and below the supply valve 123. This initial jump, allows the supply 
valve operator 125 to unseat the quick service valve 128 against the brake 
pipe pressure and the spring 129 to unseat the quick service valve 128. 
Once the quick service valve 128 opens, a sudden reduction of the brake 
pipe occurs locally as pressure flows into the quick service volume 
keeping the quick service valve 128 open. While the quick service 128 is 
open, continuous quick service or accelerated application occurs from the 
quick service volume through the continuous quick service choke 133 to 
exhaust. Once the quick service valve is closed, the quick service volume 
continues to bleed down through the continuous quick service choke 133. 
Should a subsequent application occur, additional quick service or 
accelerated application would occur because the quick service volume is 
continuously exhausted. 
While the brake cylinder pressuring is increasing to a final ratio defined 
by the surface of piston 112 and that of piston 102, brake pipe pressure 
will continue to exhaust through the continuous quick service choke 133. 
Once the ratio is met, the quick service valve 128 closes concluding the 
accelerated application and subsequently the supply valve 123 will close. 
When the brake cylinder is nominally 15 PSI, the in-shot valve 139 will 
move up choking further flow of supply reservoir to a service rate. The 
emergency relay valve 151 stays open during service application. 
Similarly, the increase brake cylinder pressure under limiting valve 136 
will cause it to move up and disconnect the quick service valve 128 and 
passage 131 from the quick service volume QS VOL and the quick service 
exhaust. Subsequent actuation of the quick service valve 128 will require 
the brake pipe first to move the limiting valve 136 down in order to 
perform a quick service or accelerated application. 
SERVICE LAP 
The position of the elements once the desire to brake cylinder to brake 
pipe ratio is established is considered the service lap position as 
illustrated in FIG. 4. Variations in brake cylinder pressure caused by 
seeping up or leaking down is automatically corrected by the relay piston 
112 and control piston 102 stack to maintain the correct ratio between 
brake cylinder and brake pipe. The piston stack 102, 112 assures a fixed 
rate of 2.5:1 of brake cylinder pressure to brake pipe pressure reduction 
independent of the volume or change of volume of the brake cylinder. The 
initial upward movement of the relay piston 112 and control piston 102, 
for small variations, are capable of opening the supply valve 123 by 
itself and without actuating the quick service valve 128. This stability 
is an improvement over prior type equipment that could not bail off 
excessive brake or resupply the brake cylinder until the limiting valve 
kick-ins at normally 10 PSI and then could only maintain this lower level 
of braking. 
SERVICE RELEASE 
For a service release, the brake pipe pressure increases and the balance 
changes between the total forces upward and downward on the piston stack 
102, 112. As the downward forces increase, the brake pipe pressure 
increase in chamber 101, the piston stack will first overcome the upward 
bias of the relay spring 119 and the upward force of the brake cylinder 
under the exhaust valve 166. Once the cage of spring 119 bottoms out, 
downward movement lifts the cage off stop 118 and compresses spring 119. 
When brake pipe is normally 3/4's PSI higher than the equilibrium force, 
the control piston operator 105 will open the brake cylinder exhaust valve 
166 as illustrated in FIG. 5. Brake cylinder pressure will exhaust through 
the annular choke area between the extension 105A of the operator 105 and 
bore 167, offsetting the increase downward force of the brake pipe. When 
release is terminated and equilibrium is achieved between the brake 
cylinder pressure and brake pipe pressure according to the predetermined 
ratio, the exhaust valve 166 will close. This is a graduated release mode 
of operation. 
Graduated release can be made in any increment from full service (normally 
26 PSI BP reduction), until brake pipe is normally 10 PSI lower than the 
initial brake pipe charge. When the brake pipe pressure is normally 6 PSI 
lower than the initial brake pipe pressure, the system will go into a 
direct or full release through a release ensuring feature. This eliminates 
stuck brakes associated with equalizing systems of the prior art. During 
graduated release, the piston stack 102, 112 and the exhaust valve 166 
cycle between the service lap position of FIG. 4 and the graduated service 
release position of FIG. 5. All the other valves in the system maintain 
their service lap position. 
A direct release occurs when the brake pipe is nominally one half of PSI 
lower than the actual supply reservoir value as determined by opening bias 
of the charging valve 155. Once the charging valve 155 opens when the 
recharge brake pipe is within one half of a PSI of the actual supply 
reservoir value, the control volume check 161 is also open interconnecting 
the brake pipe and the control volume. This causes chamber 101 above the 
control piston 102 and chamber 103 below the piston 102 to be equalized. 
This removes a major upward force from chamber 103 and causes the piston 
stack 102, 112 to assume a direct or full release position as illustrated 
in FIG. 2. Exhaust valve 116 remains open and the brake cylinder is 
completely vented to atmosphere. With the decrease in brake cylinder 
pressure, first the in-shot 139 moves to its unrestricted position and 
subsequently the limiting valve 136 opening. Emergency relay valve 151 
remains open during service release. Spring 119 moves the relay piston 112 
to its fully release and charging position separating operator 115 of the 
relay piston 112 and operator 104 of the control piston 102 as illustrated 
in FIG. 2. 
The range of graduated release and value of brake pipe at which direct 
release or release ensuring occurs will depend upon the amount of service 
brake application. As illustrated in FIG. 6, the supply reservoir pressure 
diminishes as a function of the amount of braking for a system fully 
charged at 90 psi brake pipe pressure. Brake cylinder pressure at full 
service is 65 PSI and brake cylinder pressure emergency is 75 PSI. For 
example, for minimum brake pipe reduction application of 6 PSI, the brake 
cylinder pressure is 15 PSI and supply reservoir would be 87.3 PSI. Thus, 
direct release would occur at a brake pipe pressure of 86.8 PSI (87.3-0.5) 
and the graduated release range would be 2.8 (86.8-84). For a full service 
brake pipe reduction of 26 PSI, (BP=64 PSI) the brake cylinder pressure 
would be 65 PSI and the supply reservoir pressure is 82.1. Thus, the brake 
ensuring or direct release will occur at a brake pipe pressure of 81.6. 
Thus, the brake pipe would have a value in the range of 64 PSI and the 
graduate release range would be 17.6 PSI. 
It should be noted that since the brake pipe is not connected to the supply 
reservoir until it is within a half PSI of the supply reservoir, the brake 
pipe is a pure control pipe in graduated release. The opening of the 
charging valve 155 connects the brake pipe and the supply reservoir 
allowing a half of PSI of air from the supply reservoir to charge the 
brake pipe thereby accelerating the propagation of the release signal down 
the brake pipe. Similarly, this limits the recharging of the supply 
reservoir from the brake pipe until the last 4-8 PSI of brake pipe 
charging to its original value. Thus release from a minimum application 
would be much faster than prior art devices due to the delayed recharge of 
the supply reservoir and the release ensuring feature. 
EMERGENCY APPLICATION 
For an emergency rate of decrease of brake pipe pressure, the control valve 
10 will move from its full release and charging position of FIG. 2 to the 
emergency position of FIG. 7. Initially, the charging valve 155 closes and 
the control and relay pistons stack 102, 112 will move rapidly upward by 
the force of the pressure in the control volume. As in a service 
application, the exhaust value 166 closes and the supply valve 123 and the 
quick service valve 128 immediately open and remain open until the 
emergency application is released. The control valve 10 does not assume a 
lap position of FIG. 4. Once the brake cylinder pressure exceeds that of 
the brake pipe pressure, limiting valve 136 closes. The in-shot 139 will 
move up at nominally 15 PSI brake cylinder pressure and will control the 
rate of the final brake cylinder pressure to allow full emergency brake 
cylinder pressure in 12-14 seconds. 
Since the supply valve 123 remains open after an emergency application and 
until released, the emergency relay valve 151 closes when the brake 
cylinder pressure is nominally 85% of the control volume pressure. Any 
leakage of the brake cylinder pressure is compensated by the emergency 
relay valve 151 opening to reconnect the supply reservoir to the brake 
cylinder through the open supply valve 123. Once the brake pipe pressure 
is decreased below 10 PSI, the accelerated release valve 171 closes 
cutting off the brake pipe from the dissipation valve 174 and passage 172 
above dissipation valve 174. When the brake cylinder pressure unseats the 
dissipation valve 174, this brake cylinder pressure fills the passage 172 
between the dissipation valve 174 and the accelerated release valve 171. 
Spring 177 closes the dissipation valve 174 trapping the brake cylinder 
pressure in passage 172. 
Since the exhaust valve 166 and the dissipation valve 174 are closed during 
emergency, only the emergency relay valve 151 can open to resupply the 
brake cylinder when the brake cylinder pressure decreases. Any increase of 
brake cylinder pressure above the valve defined by the emergency relay 
piston, cannot be bailed off by the closed exhaust valve 160 since the 
piston stack 102, 112 is inoperable. This is a safety feature to prevent a 
malfunctioning cylinder from bailing off the entire supply reservoir when 
the car is parked for extended periods. 
EMERGENCY RELEASE 
As the brake pipe is recharged after an emergency application, the 
accelerator release valve 171 is open when the brake pipe pressure exceeds 
10 PSI as illustrated in FIG. 8. This connects the brake cylinder to the 
brake pipe 1.5 through the open dissipation valve 174 and the accelerated 
release valve 171. This charges the brake pipe from the brake cylinder 
propagating the release signal or build-up through the system. The 
dissipation valve 174 will remain open until the brake pipe is nominally 
10 PSI lower than the brake cylinder pressure. When the dissipation valve 
174 is open, the emergency relay valve 151 will open attempting to 
maintain the pre-determined 85% ratio between the control volume and brake 
cylinder. This will drain down the supply reservoir until the supply 
reservoir and brake cylinder pressure are equal. 
Once the brake pipe pressure is within 10 PSI of the brake cylinder 
pressure, the control and the relay piston stack 102, 112 will move down 
to the graduated relay position of FIG. 5, opening the brake cylinder 
exhaust valve 166 and closing the quick service valve 128 and supply valve 
123. As the brake pipe pressure comes within a half of PSI of the reduced 
supply reservoir pressure, the charging valve 155 will open and the system 
will go into a direct release mode or a release ensuring. As noted 
previously, the emergency relay valve 151 has reduced the supply reservoir 
during the initial accelerated release condition. Thus the release 
ensuring will occur at the lowest possible brake pipe pressure after an 
emergency application. The limiting valve 136 is closed by the emergency 
brake application and remains closed until the brake pipe pressure during 
release is greater than brake cylinder pressure. The closed limiting valve 
136 prevents the brake pipe charging after an emergency application from 
being diminished by filling the quick service volume and being exhausted 
through the continuous quick service choke 133. 
MANUAL RELEASE VALVE 
Manual Release Valve 40 is illustrated in detail in FIGS. 9 and 10 
connected directly to the control valve 10. The illustrated control valve 
10 differs from that in FIGS. 2-8 in minor aspects which does not change 
the previously described operation. There is a schematic representation 
and the connection may be either directly or through the pipe bracket 30. 
The release valve 40 provides for the release of the brake cylinder and 
exhaust of the supply reservoir. An additional passage 178 is shown 
connecting passage 150 from the supply reservoir to the manual release 
valve 40 and passage 120 connecting the supply valve 123 to the brake 
cylinder is shown split in two as portions 120A and 120B at its connection 
to the manual release valve 40. 
The manual release valve 40 includes a housing 400 having a release rod 401 
extending therefrom. A cage 402 moves up and down in response the 
actuation of rod 401 against spring 403. Openings 404 in the cage 402 
provides communication through the cage to the atmosphere. A supply 
reservoir operator 405 extends from the cage 402 as does brake cylinder 
operator 406. A cage 407 with spring 408 connects the brake cylinder 
operator 406 to the cage 402. A supply reservoir valve 409 has a valve 
seat 410 on the end of bore 411. The supply reservoir operator 405 opens 
the supply reservoir valve 409 against spring 412. Passage 413 connects 
the open supply reservoir valve 410 to passage 178 which is connected to 
passage 153 and the supply reservoir. 
A brake cylinder valve 414 cooperates with the seat 415 on bore 416 which 
is connected to atmosphere. A spring 417 biases the valve 414 against seat 
415 and against the operator 406. A second seat 418 on bore/passage 419 
also cooperates with brake cylinder valve 414. Passage 420 connects the 
chamber between the seats 415 and 418 of the brake cylinder valve 414 to 
the chamber on top of piston 421. The chamber on the bottom of piston 421 
is connected through passage 422 to passage 120A of the control valve 10 
which is connected to the supply valve 123. 
An exhaust valve 423 cooperates with exhaust seat 424 connected to 
atmosphere and a second seat 425 connected to passage 422. Spring 426 
biases the valve 423 against the exhaust seat 424. Passage 427 connects 
the chamber in which the valve 423 operates to passage 126B of the control 
valve 10 and the brake cylinder. 
In the unactuated position as illustrated in FIG. 10, supply reservoir 
valve 409 rests on valve seat 410 and disconnects the supply reservoir 
from atmosphere. Similarly, brake cylinder valve 414 rests on seat 415 
cutting off passages 419 and 420 from atmosphere. Since valve seat 418 is 
open, the top and bottom of piston 421 are connected to each other and 
spring 426 biases exhaust valve 423 onto seat 424 disconnecting passages 
419, 422 and 427 from atmosphere. This also interconnects passages 422 and 
427 which interconnects the supply valve 123 to the brake cylinder via 
120A and 120B. 
When the rod 401 is manually actuated, cage 402 and operator 405 moves 
upward opening supply reservoir valve 409 thereby connecting passage 413 
and the supply reservoir to exhaust. Operator 406 moves brake cylinder 
valve 414 off seat 415 and on to seat 418 as shown in FIG. 10. This 
connects passage 420 and the top of piston 421 to atmosphere and 
disconnects passage 419 from passage 420. Thus brake cylinder pressure 
below piston 421 forces the piston 421 up against spring 426. This moves 
valve 423 off seat 424 connecting the brake cylinder to atmosphere. 
Further upward movement causes valve 423 engage seat 425. The brake 
cylinder is continuously connected to atmosphere and passages 422 and 120A 
are disconnected from the brake cylinder passages 427 and 120B and 
atmosphere. This maintains any pressure from the open supply valve 123 
onto the bottom of piston 421 which maintains the exhaust valve 423 open 
to continuously exhaust the brake cylinder. When rod 401 is released, 
valves 409 and 414 return to their position shown in FIG. 9. This will 
cut-off the venting of supply reservoir but not the venting of the brake 
cylinder since the piston 421 is locked in its upper position. Piston 421 
will only return to its lower position if the manual release was held open 
long enough to reduce the supply reservoir pressure through open valve 109 
below that of the force supplied by spring 426. Thus, the supply reservoir 
is exhausted as long as the release valve 40 is actuated and the brake 
cylinder is exhausted once the manually release valve 40 is actuated and 
until reset by spring 426. 
Although the present invention has been described and illustrated in 
detail, it is to be clearly understood that the same is by way of 
illustration and example only, and is not to be taken by way of 
limitation. The spirit and scope of the present invention are to be 
limited only by the terms of the appended claims.