Note: Descriptions are shown in the official language in which they were submitted.
115828B
- Description
Parking Brake System
Technical Field
This invention relates to brake apparatus,
and more particularly, to a hydraulic brake apparatus
for a vehicle which is able to provide a variety of
brake apparatus conditions.
Background Art
When a hydraulic system failure occurs or
when the engine is not running to drive the pump for
the brake system in vehicles having spring~appliedg
pressure-release brakes3 the brakes are spring-
applied by the failure or loss o~ such vehicle
hydraulic pressure. When such failure or loss
occurs, a vehicle of this type cannot be towed ~o a
suitable repair station until the brake cylinders are
again pressurized to provide release of the brakes
Accordingly, it is necessary and
conventional to provide a means o~ independently
pressuring the brake cylinders for release thereof
when system hydraulic pressure fails or is lost by -
connecting a manual pump to the brake system.
- Additionally, it is necessary from time to
time to bleed the system by bleeding out the
hydraulic brake system to purge air-therefrom. It is
therefore des~rable to pro~ide a hydraulic brake
apparatus that will facilitate bleeding of the brake
system when required.
In addition to the above, vehicle hydraulic
systems usually provide application of system fluid
pressure to a transmission for operation thereof,
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along with application of such fluid pressure to the
brakes to provide release of the brakes. It is therefore
desirable to provide for checking system fluid pressure by
isolating the brake system from fluid pressure applied ~o
the transmission, to provide a check of the operation of
such transmission. Such a system would insure tha~ the
brakes are applied while isolated from system pressure
when the transmission is being checked.
The present invention is directed to overcoming
one or more of the problems as set ~orth above.
Disclosure of Invention
To this end, the invention provides in a braking
system having a normally spring applied, hydraulic
pressure releasable brake, a hydraulic pressure supply
line, a brake pressure line, a hydraulic reservoir line,
and a pump having an inlet passage and an outlet passage,
the improvement comprising: multiple position connection
means for selectively communicating the brake pressure
line with one of the hydraulic pressure supply line and
with the pump outlet passage, and the hydraulic pressure
supply line with the hydraulic reservoir line, the
multiple position connection means including: a first port
in communication with the hydraulic pressure supply line;
a second port in communication with the brake pressure
line; a third port in communication with the manual pump
outlet passage; and means for selectively providing
hydraulic communication between a selected pair of said
first, second, and third portsO
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Brief DescriPtion of Drawings
Fig. 1 is a schematic view of a system embodying
the present invention;
Fig. 2 is a schematic view of a system including
5an alternative embodiment of the present invention;
Fig. 3 is a plan view of the valve of the system
of Fig. 2;
Fig. 4 is a side view of the valve of Fig. 3;
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--4--
Fig. 5 is a sectional view taken along the
line V-V o~ Fig. 4;
Figo 6 is a view similar to that shown in
Figo 5, with the valve in a second operating mode;
Figo 7 is a view similar to that shown in
Figs. 5 and 6, with the valve in a different
operating mode; and
Fig. 8 is a view similar to that shown in
Figs. 5-7~ with the valve in yet another operating
mode.
Best Mode of Carryin~ Out the Invention
- Referring to Fig. 19 the brakes o~ a
vehicle are shown generally at 10 connected
hydraulically to a brake pressure line 12. The
brakes are o~ the conventional type wherein
application o~ pressure thereto through line 12
overcomes the spring ~orce of biasing springs, not
shown3 to release the brakes, while release of
pressure ln line 12 allows the spring force o~ the
biasing springs to apply the brakes.
A terminal board 14 is provided having
ports 16,18 and 20 provided therein. Brake pressure
i
line 12 terminates at port 16 of the terminal board~
A pressure supply lîne 22 terminates at port 20 o~
the terminal board and communicates with a vehicle
hydraulic pressure source 24. A manual pump line 26
terminates at port 18 and communicates with a manual
pump assembly shown generally at 28; A supply line
30 communicates the manual pump assembly with a
hydraulic system fluid reservoir 32~
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The manual pump assembly 28 includes a
housing 34 having a pump cylinder 36, a piston 38
manually reciprocable within the cylinder by means of
a rod 40 provided with a handle 42Y Cylinder 36 is
communicated by a passageway 44 which communlcates
with inlet and outlet passages 46 and 48 through a
cross bore 50. A suction check valve 52 is provided
in cross bore 50 and an outlek check valve 54 is
provided in outlet passage 48 so that when pump rod
40 is manually reciprocated, fluid will be drawn in
from reservoir 32 through supply line 30, inlet
passage 46~ suction check valve 52, cross bore 50,
and passageway 44; and out through passageway 44g
cross bore 50, outlet check valve 54~ outlet passage
48 to manual pump line 26.
The check valves 52 and 54 comprise valve
elements 56 and 58 which are slidable within bores 50
and 48 and are biased against seats 60 and 62 formed
by narrowed end portions of bores 50 and 48, by
springs 64 and 66 secured by retainers 68 and 7Q~
Retainer 68 is retained in bore 50 by a cap
72 which is threadably secured in the end of bore 50.
Also provided in housing 34 is a pressure
relief passage 74 communicating inlet bore 46 and
outlet bore 48, which has a pressure relie~ valve 76
provided therein. Relief valve 76 includes a valve
element 78 which ~s seated agalnst a necked down
portion of passage 74, and is retained there by a
relie~ pressure spring 80 which is retained and
adjustably tensioned by a retainer 82 which is
threadably disposed in a bore 84. Relief valve
.
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76 limits the maximum pressure in ~he brakes 10
created by manual pump 287
Also provided in housing 34 is a bore 86
which also communicates inlet bore 46 and outlet bore
43. A release valve assembly 88 is disposed in bore
86 to provide for releasing of ~luid pressure to the
fluid reservoir 32 ~o again apply the brakes after
emergency towing has been compleked. Valve assembly
88 includes a valve element 90 which is seated
against a seat 92 formed by a necked down portion o~
bore 86. Element 90 is biased against seat 92 by a
spring 94 retained by a retainer 96 secured in bore
86 by a cap 98, Retainer 96 also rekains retainer 7
in outlet bore 48, A gland 100 is disposed in the
end of housing 34 opposite element 90 and has a valve
rod 102 slidable khere~n. The internal end of rod
102 has a finger 104 provided thereon and arranged to
engage valve element 90. The external end is
~rovlded with a handle 106 so that rod 102 can be
manually pushed inward to unseat valve element 90 and
release any fluid pressure in line 26 ko reservoir
32,
Terminal board 14 also has ports 108 and
110 which are the terminations of brake bleed lines
25 112 and 114, respectively, Ports 108 and 110 are
normally closed as by threaded caps but may be opened
by removing such caps for bleeding o~ the brakes,
A U-tube 120 is adapted to being coupled ko
two of ports 16~ 18 and 20.
An alternative embodiment of the present
invenkion is provided. Referring to Fig. 2~ a
vehicle system is shown which includes brakes
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130 which include brake feed lines 131 and brake
bleed lines 132 which are releasable by fluid
pressure in a brake pressure line 133. The bralce
pressure line, a fluid pressure line 134, a reservoir
return line 136 and a brake exhaust line 138 are all
communi~ated with a valve shown generally at 140.
Referring to Figs. 5-8, the valve 140
includes a valve body 142 having a central bore 144
and means defining four radial ports 1l16, 148, 150
and 152~ and an axial port 154 (see Fig. 3~. A valve
element 156 is rotatable within valve body 142 and
movable by means of a handle 158 affixed thereto
(Figs. 3 and 4).
Valve element 156 is prov~ded with an
angled passage 160 which communicates axial port 154
with one of the radial ports 146, 148, 150 or 152;
and a peripheral passage 162 which communicates
adjacent other o~ the radial ports 146, 148, 150,
152.
Referring to Fig. 2, the fluid pressure
line 134 communicates pressurized hydraulic fluid
f~om a replenish and relief valve o~ the vehicle
hydraulic system (no~ shown) to axial port 154 of
- valve body 142. Brake pressure line 133 communicates
radial port 146 with lines 131 and the brakes 130.
Brake exhaust line 138 communicates brake bleed line
132 to port 150. Brakes 130 provide communication
therethrough between feed lines 131 and bleed lines
132. E~haust line 138 has a check valve 164 therein
for blocking reverse flow therethrough from valve 14
to the e~haust side of brakes 130, but allowing flow
in the opposite direction through line 138.
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A manually actuated fluid pump is shown
schematically at 166. The pump includes a cylinder
168 having a piston 170 reciprocally disposed
therein, a connecting rod 172 affixed to piston 170
and extending from cylinder 168, and a lever 174
pivotally mounted on a frame 176 and connected to the
extending end of the connecting rod 172 by a link
178. lt will be understood that movement of the
lever in the manner shown by the arrows in Fig. 2
causes piston 170 to move within cylinder 168.
A pump line 180 communicates the cylinder
head end of the pump cylinder 168 wit`h port 148 of
the valve body 142~ The line 180 has a check valve
182 therein for allowing flow from the head end of
the cylinder 168 to port 148g but blocking flow in a
reverse directlon. A pump feed llne 184 communicates
the head end of cylinder 168 with return line 136 and
port 152 o~ valve body 142~ Line 184 has a check
valve 186 therein for allowing flow in the direction
from line 136 to the cylinder head, but blocking flow
in the opposite direction~
A shunt line 188 interconnects line 180 and
line 184g and includes a spring-biased relief valve
190 therein which prevents over pressurizing of the
brakes by the hand pumpO
As depicted in Figs~ 2 and 5-8g valve body
142 includes a groove 192 provided adjacent valve
element 156 between ports 146 and 148 to provide a
restrictive orifice therebetween for-purposes
described hereinbelow.
~ ~5828~
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Industrial Applicability
Under normal operation~ U-tube 120 is
connected between terminal board ports 16 and 20 so
that fluid pressure line 22 is communicated to brake
pressure line 12 for pressure release of the brakes.
If there is no fluid pressure to the brakes or if
there is a ~ehicle failure with a resultant failure
of the hydraulic system pressure~ the brakes will be
applied by the brake springs. If it is desired to
tow the vehicle ~o a repair facility, the U-tube is
removed from port 20 and connected to port 18~ thus
communicating manual pump line 26 with brake pressure
line 12.. The brakes may then be pressurized for
release thereof by manual reciprocation of handle 42
and rod 40, which pumps fluid to the brakes from
reservoir 32 through check valves 52 and 54~ When
towing is completed and it is desired to again set
the brakes by the release o~ the brake springs,
handle 106 ls depressed to open release valve 88 and
exhaust brake pressure line fluid to reservoir 32
- With the U-tube connected between ports 16
and 18 the brakes 10 may be individually bled very
e~fectively by opening ports 108 and 110 and pumping
.fluid through the brake system by means of the manual
- 25 pump Upon completion of the bleeding, ports 108 and
110 are closed and U-tube reconnected between ports
16 and 20
- If it is desired to check system pressure,
the brakes may be isolated from the-vehicle hydraulic
system by connecting the U-tube between ports 18 and
20 insuring that: the brakes are applied when the
system pressure is being checked~
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It will be understood that whenever U-tube
120 is connected between any two o~ ports 16, 18 and
20~ the third port is closed by a cap (not shown~.
The coupling of the U-tube and cap to the
ports of the terminal board requires some kools and
time in altering the mode of the vehicle. However,
the apparatus of the present invention is intended
for use for purposes and conditions when the vehicle
is under the control of service personnel rather than
operating personnel~
Such an arrangement prevents inadvertent
change of the vehicle mode by an operator who may not
be thoroughly familiar with abnormal vehicle
equipment and operatlng modes. However, a system may
be desired that facilitates operation by operating
personnel without a requirement for tools or time in
altering the vehicle mode.
Pins 194 and 196, shown in Figs~ 3 and 4
- are disposed on valve body 142 to interfere with a
projecting nose portion 198 of handle 158 to prevent
rotation of handle 158 and valve element 156 from the
normal mode directly to the brake release modes as
wlll be described,
Valve body 142 has mounted thereon a limit
switch 200 (Figo 3) including a spring-biased arm 202
having a roller 204 mounted thereto in rolling
contact with a cam surface 206 secured to handle 158.
A lobe 208 of the cam sur~ace 206 is positioned such
that arm 202 is forced to retract when valve 140 is
moved ~o the position shown in Fig. 8, whereby limit
switch 200 is opened. Limit switch 200 is-
operatively connected with the engine of the vehicle
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so that when limit switch 200 is open, the vehicle
engine cannot be started. In the remaining positions
of handle 158, roller 204 is not on the lobe of cam
surface 206, and the engine may be started.
Considering the alternative embodiment
described, brakes 130 as shown are used for braking
of' a vehicle~ With valve 140 as shown in Figs. 2 and
3-5, axial pork 151J communicates with port 146
through valve element 156, while port 150
communicates with port 148. Meanwhile, port 152 is
blocked from communication. Application of fluid
pressure to port 154 and through valve element 162
communicates fluid pressure to port 146, and through
line 133 and lines 131 to brakes 130 for pressure
relief o~ the brakes~ Since lines 131 are in
communication with lines 132a respectively, fluid
pressure is also applied through lines 132, through
line 1383 to port 1509 then khrough valve element 156
to port 148, into line 180 and against the relief
valve 190, The pressure setting of the relief valve
is higher than the pressure from fluid pressure line
- 134 and that required to release the brake. Relief
valve 190 effectively blocks the passage of fluid
from the brakes 130 through line 180,
It will therefore be seen that brakes 130
may readlly be released against the force of the
springs thereof in the above-described manner~ In
order to apply brakes 130, pressure is rele~sed from
line 134, allowing pressure release from brakes 130
in a manner opposite to that described above~ and the
springs of brakes 130 will then provide appllcation
thereof to brake the vehicle.
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If it is desired that brakes 130 of the
vehicle be bled, the valve element is moved by means
of handle 158 to the position sho~n in Fig. 6. This
provides that portion 6 and shown in Fig. 2 is in the
5 place Or portion 5 Communication is then provided
between axial port 154 and port 148 through the valve
element. Communication is also provided between port
150 and port 1524 Port 146 is blocked from
communication; except, as noted above, such port
10 communicates with port 148 through orifice 1920
Fluid pressure is applied through line 134 and
through valve element 156 to port 148, and throu~h
orifice 192 to port 146. The fluid pressure is then
applied to line 133 and to the lines 131g through
15 brakes 1303 to lines 132 and line 138, past check
valve 164 to port 150; then through the valve element
to port 152, into return line 136 to the transmission
reservoir Orifice 192 allows a small amount of
fluid flow to take place along the path just
20 described, insuring that such flow is limited and
regulated to provide that any air in the system is
properly purged3 Because of the pressure drop
created by orifice 192, insufficient pressure is
directed to the brakes for their release during the
25 bleed mode. It wlll readily be seen therefore that a
highly ef~icient and simple system of bleeding of the
vehicle brake system is provided by the present
invention.
Again3 during normal vehicle operation,
30 valve element 156 may be moved to the position shown
- in Fig. 7, corresponding to a position in Fig.
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2 wherein the portion 7 is moved into the position
originally held by the portion 5. Valve element 156
thereby provides communication between port 154 and
port 150, and also bel;ween port 146 and port 152,
5 with port 148 being hlocked. With the valve element
in this posi tion, communication is provided between
line 133 and line 136 through valve element 156~ so
that lines 131 communicate with drain, releasing any
fluid pressure on brakes 130. Thus, brakes 130 are
lû in an applied state. Meanwhile~ pressure may be
built up in line 134 and maintained therein because
of check valve 164 in line 1380 This pressure
buildup providesg in turn, pressure buildup in the
transmission of the vehicle. It will thus be seen
15 that the transmission may be tested in its
pressurized state while pressure is released from
brakes 130 to insure that they are ln an applied
state~
In the case wherein, for example~ the
20 vehicle is operating normally with valve element 156
in the position shown in ~ig. 5, upon engine f'ailure;
pressure will no longer be maintained in line 134.
Rather, pressure will be released therefrom and from
brakes 1309 so that brakes 130 are then in a spring-
25 applied state~ It may khen be desirable to tow theinoperative vehlcle to a place wherein it can be
conveniently repaired.
In such case, the valve element is moved to
the position shown in Fig. 89 moving the portion 8
30 into the position of the original portion 5. ~lalve
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element 156 thereupon provides communication between
port 146 and port 148, and also be~ween port 154 and
port 152, with port 150 being blocked. Movement of
the pump lever 174 in a rightward direction moves
piston 170 rightward to draw fluid into pump 166 from
lines 134 and 136 and into the cylinder head past
check valve 186. Subsequent movement of pump
actuating lever 174 in a leftward direction forces
the fluid in the cylinder head~ past check valve 182
through line 1803 into port 148~ then through valve
element 156 and out port 146 into line 133, so that
fluid pressure is applied to li.nes 131 and to brakes
130~ Fluid pressure buildup is maintained in lines
132 because line 138 is blocked at port 150.
Continued back and-forth movement of actuating lever
172 will provide a repetition o~ this step to build
up fluid pressure applied to brakes 130 until such
pressure is sufficient to release brakes 130. The
vehicle may then be towed as appropriate ~o a place
wherein repairs can be undertaken. Relief.valve 190
lirnits the manually pumped fluid pressure in the
brakes to protect, the brakes against excessive
pressure. Limit switch 200 insures that with ~alve
- element 156 in this stage, the vehicle engine cannot
be started because lobe 208 of cam surface 206 is in
- contact with roller 204 of limit switch 200, insuring
that the limlt switch 200 is in an open position.
It should be noted in Figs. 3 and 4 that
- pins 194 and 196 are secured to.valve body 142~ and
positioned to be contac~ed by nose portion 198 of the
handle 158~ so that valve element 156 cannot be moved
directly from the position just described (i.e~
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-15-
~ig. 8) to the normal operating position shown in
Fig. 5. If this movement could be undertaken, it is
possible that pressurized fluid could be ~rapped in
the line while limit switch 200 could be closed to
again allow starting o~ the engine. Such pressure o~
trapped oil might be sufficient to prevent brake
application during initial start-up operation of the
vehicle, leading to a hazardous situation. By
placement of the pins as shown, the handle must be
moved bac~ through the stages shown in Fig. 7 and
Fig. 6, to that shown in Fig. 5. With valve element
156 as shown in Fig. 7, it will be remembered that
` the line 133 is in communication with the
transmission reservolr through valve element 1569
insuring that ~luid pressure is released from brakes
1300 Thus, the problem of possible trapping of
pressurized fluid described above is avoided.
Other aspects, ob~ects and advantages of
this invention can be obtained ~rom a study o~ the
drawings, the disclosure, and the appended claims.
