Residual pressure relief valve for brakes

An automatic brake release valve in the form of a normally open pressure relief venting structure for air operated vehicular brakes and the like, wherein atmospheric air is vented into the closed brake system intermediate the air brake actuating valves and the brake chambers actuated thereby. This venting valve structure relieves any pressure build-up which occurs as a result of brake valve leakage, since any increase in pressure in this part of the system closes the exhaust valves and actuates the brakes. So that normal brake function is maintained, the venting valve structure closes on a predetermined pressure rise. Thus, when the brakes of the vehicle are applied, a limited amount of air will escape from the system, until the predetermined valve closing pressure is reached, and during this air escape period, water condensate is exhausted from the system automatically, while providing maximum brake efficiency.

BACKGROUND OF THE INVENTION 
For many, many years, over the road vehicles have encountered severe brake 
drag problems as a result of residual pressure build-up in the brake 
system, which problem has been accepted by the trucking industry because 
of the lack of a satisfactory solution. 
In actuality, foot operated brake valves are equipped with either a treadle 
or a lever connected to linkage for use with a conventional brake pedal or 
treadle. In operation, when the pedal or treadle, as the case may be, is 
actuated by the driver's foot, force is applied by means of a resilient 
plunger acting against a piston. As the piston is moved, the exhaust port 
is closed and the air inlet is opened. Air pressure from the supply 
reservoir then flows by the inlet valve and out the delivery ports to the 
brake chambers which apply the brakes. 
When the air pressure in the cavity beneath the piston and the air pressure 
being delivered to the brake chamber actuators is equal, the mechanical 
forces on the top of the piston permits the inlet to close, which cuts off 
any further flow of air from the supply line through the valve and the 
exhaust remains closed to prevent the escape of air pressure through the 
exhaust port. 
When the pedal or treadle force is removed and the mechanical force removed 
from the top of the piston, then the air pressure beneath the piston moves 
the piston to open the exhaust port. The air below the piston and in the 
delivery lines is then exhausted through the exhaust port. 
When quick release valves are used, the quick release valve exhausts the 
brake chamber air pressure and functions to speed up brake release time by 
reducing the distance the exhaust air must travel to reach the exhaust 
port. The quick release valve is operated by air pressure from the brake 
valve entering the top port on the release valve which forces a diaphragm 
against an exhaust port seat. This blocks off the exhaust port and permits 
pressurized air to pass around the edges of the diaphragm and out of each 
of the side outlets to the brake chambers. As the air pressure is released 
from above the diaphragm, the air pressure and spring below force the 
outer edge of the diaphragm to seal on the valve body and at the same time 
opens the exhaust port seat, opening the exhaust, which opens the brake 
chambers directly through the exhaust port to atmosphere. 
When relay valves are used, the function is much the same as the quick 
release valves, in that the relay valves are high capacity brake valves 
which serve as relay stations to speed up application and release time of 
the brake system. 
Therefore, from the foregoing, it would appear that there is no need for 
the proposed invention, since the brake chambers can be readily exhausted 
and this is almost true, except for the fact that the exhaust ports in the 
brake actuating valves, the quick release valves and the relay valves are 
large and must be immediately closed upon the application of any increased 
air pressure in the brake system, otherwise the pressurized air escape 
would be enormous and when the exhaust ports finally closed, the applied 
brake chamber pressure would be high and the brakes would grab and smooth 
stops would be impossible, let alone the damage to the equipment. 
SUMMARY OF THE INVENTION 
It is now apparent that the proposed invention has a place in the modern 
vehicular brake system, because it functions in a range where existing 
control valves do not operationally function, nor is a satisfactory valve 
available currently in the marketplace. Thus, the introduction of a low 
pressure transducer with a restricted or limited exhaust orifice for the 
control of residual pressure build-up is a very necessary device, when 
properly installed intermediate the brake actuating air inlet valve and 
the brake actuating chambers, which valve in no way interferes with the 
operation of the existing brake system and when installed in a brake 
system will pass the Department of Transportation (DOT) total system 
actuation/shut-down, pressure drop test. The elimination of residual 
pressure build-up automatically results in substantially better vehicular 
performance and the reduction of fuel consumption, tire, brake and engine 
wear etc., as well as a reduction in the vehicular maintenance down-time. 
The proposed residual pressure transducer provides safety assurance and 
cycle to cycle operational reliability with minimum maintenance through 
replacement at pre-determined time or usage intervals. The operational 
pre-determined characteristics of the residual low pressure actuated 
transducer also functions to assist in the exhaust of water condensate 
found in the brake system. 
While the system has been described in connection with and using only 
pneumatically operated valves, the system can be functional by the use of 
a pneumatically actuated snap action switch which operates a normally 
open, small orifice solenoid valve, provided the equipment is located 
intermediate the brake actuating inlet valves and the brake actuating 
chambers. 
Such pressure actuated switches are manufactured by several well known and 
reputable firms and are available from manufacturer's representatives 
throughout the country, as are the small orifice solenoid valves. The snap 
action switch is necessary because of the current draw of the solenoid, 
which might result in pits and burning of the conductor contacts that 
would result in pre-mature failure of the switch. To help control this 
condition, the snap action switch closes at a higher pressure than it 
opens, thus when it closes on assending pressure, it will not continue to 
make and brake in the event of a slightly modulating pressure variation, 
which will of course extend the life of the switch. The snap action switch 
does of course open on decending pressure below the actuating pressure, 
for the same reasons above mentioned. 
FIG. 14 of the drawings illustrates the above described structure, wherein 
the snap action pressure switch PS is installed in the service line, as is 
the small orfice, normally open solenoid valve NOSV. The normally open 
solenoid valve NOSV may be positioned adjacent the snap action pressure 
switch PS and on either side thereof, without departing from the spirit 
and scope of the proposed invention. When the snap action pressure switch 
PS is activated, a circuit from the battery B is made, which closes the 
normally open, small orfice, solenoid valve NOSV and returns the that 
portion of the brake system intermediate the brake actuating valves and 
the brake chambers BC to the closed state without any interference to the 
brake system. 
From the foregoing, it will be obvious that in a vehicular brake system 
which has an air storage reservoir tank which is maintained within a 
pre-determined pressure range by an engine driven compressor and employing 
a plurality of brake actuating chambers, with each brake chamber being in 
communication with the pressure source, and having air brake actuating 
valves disposed intermediate the pressure source and the brake actuating 
chambers for the control of air passage from the pressure source to the 
brake actuating chambers, with an automatic residual pressure relief 
venting structure being provided intermediate the brake actuating valves 
and the brake actuating chambers for the disipation of any residual 
pressure build-up caused by any reason whatsoever, is a safer and more 
utilitarian vehicle. 
Such an automatic brake release valve is assembled from a plurality of 
elements which form an expendible, dual compartment, pressure actuated 
transducer, which compartments are separated by a motion transmitting 
diaphragm member positioned between the main body housing member and the 
cover therefore, with at least one of said compartments being vented to 
the atmosphere, means communicate at least one of the said compartments 
with the pressure source when the air brake actuating valve is opened, 
while closure means are provided intermediate said motion transmitting 
diaphragm member and the vented compartment, with resilient means in the 
form of a compression spring being provided to maintain said closure means 
open to atmosphere in the vented compartment until the pressure source 
exceeds the force exerted by the resilient means, at which time the 
closure means shut the vents to prevent further loss of air, thus 
returning the brake system to the closed condition for normal operation. 
Other beneficial results will accrue from the use of the proposed invention 
when it is properly installed in a vehicular brake system, most of which 
will appear in the following description and appended claims, reference 
being had to the accompanying drawings which form a part of this 
specification, wherein like reference characters designate corresponding 
parts in the several views.

NOW THE INVENTION 
While the proposed invention may have numerous embodiments, it must be 
understood that the invention is not limited in its application to the 
details of construction and arrangement of parts illustrated, since the 
invention can be carried out in various ways and that the phraseology and 
terminology employed herein is for the purpose of description and not of 
limitation. 
The utility of the proposed invention is enormous, since its usage results 
in economies heretofore unimaginable in the trucking industry. The 
proposed pressure relief venting valve structure is used on pneumatically 
operated vehicular brakes and the like and permits atmospheric air to be 
introduced into the brake system intermediate the air brake actuating 
valves and the brake chambers actuated thereby. When the brake actuating 
air valve is opened to the pressurized air source, the ascending air 
pressure upon reaching a pre-determined amount closes the pressure relief 
venting valve so as to provide the normal closed brake system operation. 
When the brakes are released and the air brake actuating valve shut-off 
from the pressure source, the pressurized air in the system is exhausted, 
which opens the relief valve so as to again vent that portion of the brake 
system to atmosphere. 
With reference to the drawings, FIGS. 1, 2, 2A and 2B are representative of 
one-half of a two part hose coupling of generally symmetrical 
configuration and adapted to be rotated for locking engagement with each 
other. The proposed residual pressure relief venting valve 10 is shown in 
FIG. 1 of the drawings assembled onto the hose coupling body 12, as is the 
case in FIG. 2. It will be observed that the locking flange which is used 
to hold both halves of the coupling together when they are rotated into 
engagement have not been illustrated, since the invention in the present 
instance relates only to the coupling body 12, which is illustrated. In 
FIG. 2A of the drawings, the coupling body 12 has positioned therein a 
threaded opening 14, which provides the means for securing the proposed 
residual pressure relief valve. The coupling seal 16 is disposed beneath 
the threaded opening 14, in the air passage 18, which intersects the 
openings in the threaded opening 14 and the seal 16. While a threaded 
opening has been illustrated, a straight passage could be employed which 
would permit a pressure relief valve to be pressed into the coupling body, 
also the opening could form one-half of a quick disconnect coupling, with 
the other half being located on the pressure relief valve, or such other 
means of expediency as may be desirable without departing from the spirit 
and scope of the invention. The hose coupling body 12A shown in FIG. 2B 
illustrates the main residual pressure valve housing 20 as being integral 
therewith and disposed opposite the coupling seal 16A and in communication 
with the air passage 18A. The specific configuration of the integral body 
housing 20 can of course be substantially identical with either of the 
body housings described in connection with any of the embodiments 
hereinafter described, such as that of FIGS. 3, 5, 8, 11 and 12 
respectively. For ease of description, the structure will be described in 
connection with each of the respective enlarged cross sectional views 
illustrated hereinafter, with the respective description being applied to 
the structure of FIG. 2B. 
The proposed structure as illustrated in connection with FIG. 3 of the 
drawings shows a complete residual pressure relief venting valve 30, the 
main body housing 32 has a flange 34 which is integral therewith, as does 
the cover 36 which has flange 38 integral therewith. The main body housing 
32 has an axial passage 42 therein, while the cover 36 also has an axial 
passage 44 therein, with the intersecting flange portions 34 and 38 being 
separated by a motion transmitting diaphragm 52, so as to define two 
compartments 46 and 48. Compartment 46 is located in the main body housing 
32, while compartment 48 is disposed in the cover member 36. Before 
assembly of the motion transmitting diaphragm 52 in the main body housing 
32, a hollow insert 54 is pressed (or threaded) into the body housing 32 
from the flanged end portion 34, the enlarged end portion thereof forms a 
stop for limiting the displacement of the motion transmitting diaphragm, 
while the reduced diameter on the opposite end of the hollow insert 54 
forms a closure seat between the cavity 56 which communicates with the 
vent openings 58 in the main body housing 32. A flanged needle shut-off 
means 62 has a resilient seal means 64 positioned therearound, while the 
hollow body portion 66 communicates with a passage that intersects 
compartment 46. The outermost end 72 of the flanged needle 62 is undercut 
and extends through a pair of flanged washers 74 and 76 which provide 
support for the diaphragm 52, and a seat for the compression spring 82 
positioned in the cover 36. When the flanged shut-off means 62 is 
assembled with the resilient seal means 64 and inserted into the main body 
housing 32, through the hollow insert 54 and the undercut outer end 72 
inserted through the openings in the flanged washers 74 and 76 
respectively, the end portion 72 is riveted over so as join the individual 
parts to the diaphragm 52 into a unitary assembly. Thereafter, the flanged 
portion 38 of the cover 36 is positioned in engagement with the outer 
diameter of the motion transmitting diaphragm 52 and securely rolled or 
swaged into sealed engagement (leak-proof) with the main body housing 
flange 34, after which the compression spring 82 is inserted into the 
axial passage 44 in the cover 36 and positioned therein by means of an 
adjustable spring retainer 84 which is in threaded engagement with a 
corresponding threaded portion in the cover 36. An opening 86 extends 
through the spring retainer 84, so as to provide an atmospheric vent for 
compartment 48 in the cover 36. Additionally, the outer surface of the 
cover member 36 has a straight knurl 88 thereon, so that if a cover (not 
shown on FIG. 3) is used to protect the spring retainer vent 86 from 
foreign objects, as illustrated in FIGS. 1, 2 and 4 by the letter "C," the 
atmospheric vent will then be located about and between the spaces formed 
by the knurl and the cover "C." It will be noted that the residual 
pressure valve 30 is shown in its closed position, which position the 
valve would assume when chamber 46 is pressurized, and upon release of the 
pressure, the relief valve 30 would then return to its normally open 
position. Should it be found desirable to increase the valve closing 
pressure, the spring retainer 84 is merely rotated to pre-load the 
compression spring 82 to a greater degree. Should a lesser load be 
desirable, the spring retainer is merely moved in the opposite direction, 
thus reducing the pre-load. 
FIG. 4 of the drawings illustrates two residual pressure relief venting 
valves 30, as shown in FIG. 3, mounted in a cross drilled body 100 in a 
generally horizontal position. The vertical opening therein intersects the 
cross drilled and threaded portions 102 and 104 respectively, although the 
cross drilled and threaded portion 102 extends completely through the body 
100, the drilled and threaded portion 104 has a flanged section 106 on its 
intermost end at the point of intersection with the vertical opening 108. 
Since difficulties are sometimes encountered in obtaining leak-proof 
threaded connections, a soft washer is disposed intermediate the flange 
portion on the main body housing of the relief valve 30 and the outer 
surface of the cross drilled body 100. This provides a simple and positive 
thread seal, without resorting to sealing compound or the use of a 
"Teflon" tape wrap, each of which are slow and cumbersome. When the 
sealing structure shown on the right side of the cross drilled body 100 is 
used, the soft washer is disposed between the bottom of the main body 
housing 32 of the relief valve 30 and the flanged portion 106 in the cross 
drilled and threaded portion 104. While the soft washer used was made from 
lead, other materials could be successfully employed with equally 
satisfactory results. 
The residual pressure relief valve shown in FIG. 5 illustrates a complete 
valve assembly 130 wherein the main body housing 132 has a flanged portion 
134 integral therewith, as does the cover 136 which incorporates the 
integral flanged portion 138. The main body housing 132 has an axial 
passage 142 therein, while the cover has plug 188 pressed into passage 144 
located therewithin. The intersecting flange portions 136 and 138 are 
separated by a resilient diaphragm 152, so as to define two compartments 
146 and 148 respectively. Compartment 146 is located in the main body 
housing 132, with compartment 148 being disposed in the cover member 136. 
The main body housing 132 axial passage 142 has a step 154 intermediate 
its ends which forms a seat for one end of the compression spring 182. The 
other end of the spring 182 is seated against a relieved portion 178 in 
the flanged hollow needle 162. Vents 158 are positioned in the main 
housing flange 134, three in number and symmetrically spaced and 
positioned as shown in FIG. 5. The motion transmitting resilient diaphragm 
152 is assembled against the flanged portion 174 of the hollow needle 162, 
while the flanged washer 176 is positioned over the end 172 of the hollow 
needle 162, which is thereafter riveted over to form a unitary assembly. A 
resilient closure seal 164 is positioned against another relieved portion 
184 in the flange 174 of the needle 162. The complete resilient diaphragm 
assembly 180 is then inserted into the axial passage 142 from the flanged 
end 136 of the main body housing 132, with the compression spring 182 
disposed between the step 154 in the main body housing 132 and the 
relieved portion 178 in the hollow needle 162. Thereafter, the cover 
member 136 is assembled into the main body housing 132, with the 
respective flanged portions 134 and 138 engaging the outer diameter of the 
resilient diaphragm assembly 180, at which time the main body housing thin 
flange is securely rolled or swaged into sealed engagement (leak-proof) 
over the cover flange 138. The adjustable plug 188 in the cover 136 is 
then properly positioned for the proper displacement of the resilient 
motion transmitting member. Serrations are found on the inner end of plug 
188, as well as on the inner surface of the cover 136, so as to permit 
pressurization of compartment 148. The vented passages 158 are 
communicated to the air source through axial passage 142 in the main body 
housing 132 and then between the space 156 between the outer surface of 
the needle 162 and the enlarged portion of the axial passage 142. 
FIGS. 6 and 7 of the Drawings delineate left and right end elevational 
views of the residual pressure relief valve structure shown in FIG. 5 of 
the drawings, illustrating the hexogonal configuration of the proposed 
valve 130 which provides a means for application of a wrench when 
assembling the valve in position for usage. While a hexogonal 
configuration is shown, other configurations could be employed with 
satisfactory results, without departing from the spirit and scope of the 
invention. 
The residual pressure relief valve shown in FIG. 8 is similar to the 
structure shown in FIG. 5, except for the location of the compression 
spring 282. The complete valve assembly 230 has a main body housing 232 
which has a flanged portion 234 integral therewith, while the cover 236 
incorporates an integral flange portion 238. The main body housing 232 has 
a generally straight axial passage 242 therein, while the cover 236 
differs from the previous structure, in that there is no axial passage 
therethrough. The intersecting flange portions 236 and 238 respectively 
are separated by a resilient motion transmitting diaphragm 252, thereby 
defining two compartments 246 and 248. Compartment 246 is found in the 
main body housing 232, with the remaining compartment being found in the 
cover 236 and identified as number 248. The axial passage 242 in the main 
body housing 232 provides a pilot or guide for the body of the generally 
hollow needle 262, while the end of the hollow needle is undercut for 
insertion through the central openings in the cup flanged spring seat 
member 274, the resilient motion transmitting diaphragm 252 and the 
flanged washer 276, with the end 272 of the hollow needle 262 being 
riveted over so as to form a diaphragm assembly 280, as shown in FIG. 10. 
Vents 258 are located in the flanged portion of the main body housing 232 
either in symmetry or in random locations. Before final assembly of the 
valve, a resilient closure seal is positioned over the outer surface of 
the hollow needle 262 and into engagement with the generally flat 
undersurface of the cup flanged spring seat member 274. The complete 
diaphragm assembly 280 is then inserted into the axial passage 242 from 
the flanged end 236 of the main body housing 232, with the compression 
spring 282 being disposed between the closure seat 264-A in the main body 
232 and the cup flanged spring seat member 274 secured to the diaphragm 
assembly 280. Thereafter, the cover member 236 is assembled into the main 
body housing 232, while the respective flanged portions 234 and 238 engage 
the outer edge of the resilient diaphragm assembly 280, at which time the 
main body housing thin flange is securely rolled or swaged into sealed 
engagement (leak-proof) over the cover flange 238. Serrations of suitable 
cross section are located on the inner surface of the cover 236, so as to 
permit pressurization of compartment 248 through the passage 266 in the 
hollow needle 262. The vented passages are communicated with the pressure 
source by means of the space 256 between the outer surface of the hollow 
needle 262 and the axial passage 242 in the main body housing 232. 
FIG. 9 of the drawings shows the inside of the cover 236, the flange 
portion 238 thereof and the serrations S which are centrally positioned 
therein. While the serrations are illustrated as being in the form of a 
cross, they be of most any size or configuration, since their function is 
to permit pressurization of the diaphragm displacement compartment 248, 
while the structure shown in FIG. 10 represents a modified resilient 
motion transmitting diaphragm assembly 280A, wherein the flanged spring 
seat 274A is notched about the circumference for ease of air passage 
therethrough, while the needle body 262A is undercut for the same reason. 
The residual pressure relief valve structure 330 shown in FIG. 11 is 
similar to the structures shown in FIGS. 5 and 8, with the exception of 
the elimination of the hollow needle. The complete valve assembly 330 
incorporates the use of a main body housing 332 and integral flanged 
portion 334, while the cover 336 has an integral flange portion 338. The 
intersecting flange portions 334 and 338 are separated by a resilient 
motion transmitting diaphragm 352, so as to define a pair of compartments 
346 and 348. Compartment 346 is found in the main body housing 332, while 
the second compartment is disposed in the cover member 336 and identified 
as number 348. The axial passage 342 in the main body housing 332 provides 
a pilot for the compression spring 382 and is seated in the step 354 in 
passage 342. The opposite end of the compression spring 382 is seated in a 
bushing 362, which is generally hollow and is used to position the 
resilient closure member 364, the resilient diaphragm and the support 
washer 376 as a unitary assembly when the end 372 is riveted over. Venting 
means are located in the flanged portion of the main body housing 332 in 
the form of a plurality of openings 358 which are disposed intermediate 
the closure means 364 and the pressure source passage 342. When the 
pressure relief valve is assembled, the resilient compression spring 382 
is deposited in the axial passage 342 and against the step 356, after 
which the resilient diaphragm assembly 380 is positioned within the 
flanged portion 334 of the main body housing 332, with the compression 
spring 382 seated in the bushing 362. Thereafter, the cover member 336 is 
assembled into the main body housing 332, while the flanged portions 
thereof 334 and 338 respectively engage and clamp the resilient motion 
transmitting diaphragm 380 into sealed (leak-proof) engagement when the 
thin flange on the main body housing is rolled or swaged over the cover 
flange 338. Serrations in the riveted end 362 communicate the pressure 
source with the compartment 348 so as to permit the pressurization thereof 
when required. Pressurization of compartment 348 in excess of the 
compression pre-load causes displacement of the diaphragm assembly 380 to 
seat the closure means 364 against its seat, and thereby shut the vents 
358 from the pressure source. 
The residual pressure relief venting valves shown in FIGS. 12 and 12A are 
similar to that shown in FIG. 3, since the valve is actuated in the 
direction of pressure source, while the structures of FIGS. 5, 8 and 11 
are actuated in the opposite direction of the pressure source. The 
proposed residual pressure relief valve structure shown in FIG. 12 is 
identified as assembly 430 and incorporates a main body housing 432 with a 
flanged portion 434, while the cover 436 is a substantially flat disc 
which may have a flanged portion 438 as shown in FIG. 12A. The axial 
passage 442 in the main body housing 432 provides a pilot for the flanged 
end of the needle 462, while the stem 454 in the passage 442 is centrally 
located in the flanged portion 434 in the main body housing 432. The 
flanged portion 463 of the needle 462 provides the seat for the 
compression spring 482 on one end, while the step 454 forms the spring 
seat on the opposite end. The body of the generally hollow needle 462 is 
undercut on its outermost end and has positioned thereover the support 
washer 474, a molded resilient motion transmitting diaphragm 452 which 
incorporates the closure means 464 integral therewith and has the second 
support washer 476 positioned in the central recess in the resilient 
diaphragm 452, after which the end 472 of the needle 462 is riveted over 
to form a unitary valve body assembly. The positioning of the resilient 
diaphragm in the main body housing 432 defines compartment 446, while the 
assembly of the cover 436 into the flanged portion 434 of the main body 
housing 432 defines compartment 448. When the assembly of the respective 
elements is complete, the thin flange on the main body housing 432 is 
rolled or swaged so as to clamp the the outer edges of the resilient 
diaphragm between the flanged portion 434 and the cover 436 in sealed 
(leak-proof) engagement. Vents 458 are found in the cover 436, which cover 
forms the seat for the closure means 464. The closure means 464 is 
disposed intermediate the vents 458 and the pressure source. Serrations 
may be used on the surface intermediate the central portion of the flanged 
main body portion 434 or on the engaging surface of the washer 474 if 
necessary, so as to more readily communicate the pressure source with the 
valve actuating chamber 446 when the pressurized air passes around the 
outer surface of the needle 462 and through the axial passage adjacent the 
step 454 therein. 
The residual pressure relief venting valve structure 530 shown in FIG. 12A 
of the drawings is an exploded view of a valve structure substantially the 
same as that shown in FIG. 12, with the exception being that the closure 
means 464 was integral with the diaphragm 452, while in the exploded view 
the resilient closure means is a separate molded part, although positioned 
in the same relative location. It will be observed that the hollow flanged 
needle 562 is inserted into the compression spring 582 and this 
sub-assembly is inserted into the axial passage 542 in the main body 
housing 532, one end of the compression spring being in engagement with 
the flange 563, with the opposite end thereof being in engagement with the 
step 554. The undercut end 572 of the needle 562 is then moved through the 
reduced diameter 543 of the axial passage 542 and through the respective 
openings in the support washer 574, the resilient motion transmitting 
diaphragm, 552, the resilient closure means 564 and then through the 
retaining support washer 576, after which the end 572 of the needle 562 is 
riveted over to form a unitary valve body assembly. The vented cover 536 
is then positioned in the outer end of the main body housing 532 and the 
thin flange 533 rolled over or swaged, clamping the outer edged of the 
resilient diaphragm 552 therebetween in sealed (leak-proof) engagement. 
The cover member 536 has a threaded extension 592 thereon which is 
cooperable with the protective deflector 596 and the threaded opening 594. 
Seal means 598 are secured by suitable means to the underside of the 
protective deflector 596, so that if a rupture should develop in the 
diaphragm 552, rotation of the protective deflector 596 into engagement 
with the surface of the cover 536 will seal same against loss of air. 
For a better understanding of the typical air brake system, FIG. 13 
delineates same, as well as the location of the residual pressure relief 
valve RPRV in the service line. The above described residual pressure 
relief valve RPRV is located intermediate the brake actuating valves (hand 
valve HV and foot valve FV) and the respective brake chambers BC. Also 
illustrated is the engine driven compressor C, which supplies the 
reservoir R and the service reservoir SR. Reservoir R is fitted with a 
safety valve SV and a drain cock DC, while the check valve CV is 
interposed between reservoir R and the service reservoir SR. The service 
reservoir SR is in communication with the foot valve FV and the hand valve 
HV, each of which are in communication with with the brake chambers BC, 
after passing thru a quick relief valve QRV on the front and rear of the 
tractor. The brake actuating valves are also in communication with a 
double check valve DCV which communicates with the tractor protection 
valve TPV which is in communication with the service line and emergency 
line between the tractor and trailer. The trailer service line and 
emergency line are joined to the trailer by means of glad hand couplings 
GHC. Intermediate the tractor protection valve TPV and the glad hand 
coupling GHC in the service line is positioned the residual pressure 
relief valve RPRV, the subject of the present invention. Both the service 
line and the emergency line are in communication with the relay emergency 
valve REV on the trailer, which is also in communication with the trailer 
reservoir TR. Also shown in the drawing is a control valve in the tractor 
only CV(TO) which communicates with a portion of the tractor protection 
valve TPV, while a low pressure indicator LPI is positioned in the line 
communicating the supply reservoir SR with the foot valve FV. A pressure 
gage PG is located intermediate the hand valve HV and foot valve FV, while 
a governor G is disposed in a line from the supply reservoir SR and the 
compressor C. A stop light SL is located intermediate the double check 
valve DCV and the tractor protection valve TPV. The total system 
functioning to stop the tractor and trailer under each and every operation 
condition. 
While the descriptions of the various embodiments are believed to be 
complete and accurate, it must be understood that variations of the 
proposed invention will occur and that future improvements will be made, 
however, at the present time there is no available valve structure in the 
marketplace which functions in the manner of the proposed invention and 
accomplishes the results obtained by the use of the proposed invention. 
There is a dire need in the trucking industry for this invention, since 
its use results in substantial efficiency increases through reduced fuel 
consumption, reduced break wear, reduced tire wear and distruction, 
reduced engine wear, reduced maintenance and reduced down-time. Driver 
time loss will likewise be reduced, since the brakes will not drag, heat 
up and seize, at which time the driver must either sit it out and wait for 
the brakes to cool so the vehicle can be moved, or he must call a tow 
truck. The alternative being the installation of the proposed invention in 
the brake system intermediate the brake actuating valves and the brake 
actuating chambers.