Note: Descriptions are shown in the official language in which they were submitted.
^- 2084~7
BRIUCB llEA}l INDICATOR
BACKGROUND OF q!HE INVENTION
1. Field of the Invention
This invention relates to air-actuated diaphragm
spring brakes having a push rod actuator. More
particularly, this invention relates to an apparatus which
alerts observers that the brakes are seriously worn or not
functioning properly, such indication remaining active
irrespective of subsequent positioning of the push rod.
2. State of the Prior Art
Air brake systems which provide an indication to
the operator of excess wear or misadjustment of vehicle
brakes have previously been described. See for example
U.S. Patent No. ~,~55,712 issued August 9, 1989 to Wiley
Jr. et al. and U~S. Patent No. ~,9~S,818 issued August 7,
1990 to Ware.
The Wiley Jr. et al. patent discloses the use of
a magnetic system having a magnet attached to the brake
push rod which moves with that push rod. A detector, which
detects movement of the magnet, is placed in a fixed
position with respect to the push rod. When an indication
is received that the magnet, and hence the brake push rod,
have moved beyond a pre-determined point, a visual or
audible indicator i8 actuated in the truck cab to signal
the operator of a brake problem. Movement of the brake
push rod beyond a pre-determined point is an indication
that the brakes have worn beyond a safe level, or that the
brakes have been misaligned or are misad~usted in some
manner, or that compl~te brake ~ailure has occurred.
The Ware patent discloses the use of a physical
indicia cut into the push rod at a pre-determined area of
the push rod. This area will be exposed to the operator's
view if the push rod is extended beyond a pre-determined
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20~43~7
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point. Again, this provides an indication to the operator
of a brake problem.
None of these prior art patents provide for the
fixing of the break wear indication signal so that the
signal remains on, once the push rod has moved beyond a
pre-determined point, irrespective of subsequent -~
positioning of the brake push rod. These prior art
monitoring devices all have the disadvantage of switching
off when the push rod is retracted after pressure is
released from the brake, and there is no permanent
indication that a dangerous brake situation has occurred.
There is a need for an apparatus to monitor
brakes which will remain fixed in position, and thereby
provide a constant signal, when the push rod has moved ;
beyond a pre-determined position, thereby providing a
permanent indlcation of excessive brake wear, misalignment
or brake failure, irrespective of the subsequent
positioning of the push rod.
8UMMARY OF THE INVENTION ~
. ~ . .
In accordance with the invention, an apparatus
for monitoring brake wear is provided for an air-actuated
diaphragm spring brake havinq a push rod connecting the `
brake to the diaphragm, the push rod mounted for reciprocal
movement between an operative position and an inoperative
position. A first member is provided connected to the
actuator having an opening for receiving the push rod for
reciprocal movement therethrough. A second member is
connected to the push rod for movement with the push rod
between the operative position and inoperative position.
The second member includes engaging means for engaging and
retaining the second member with respect to the first
member when the second member is reciprocated by the push
rod to a first predetermined position with respect to the
first member,the first predetermined position being
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indicative of an actuator potential brake problem. The
engaging means retains the second member with respect to
the first member irrespective of subsequent movement of the
push rod. An alarm is provided and an alarm actuating
means which is responsive to movement of the second member
with respect to the first member for actuating the alarm
when the second member is reciprocated beyond said first
predetermined position, with respect to the first member.
~RIFF DB8CRIPTION OF T~F DRA~ING8
FIG. 1 is a cross-sectional view of an air-actuated
diaphragm 5pring brake showing a brake wear
indicator according to the invention with the
brake released.
FIG. 2 is a cross-sectional view of the diaphragm spring
brake of FIG. 1 in an operative position with
brakes applied, the brakes being adjusted to a
safe position and the indicator showing "green".
' :
FIG. 3 is a cross-sectional view of a diaphragm spring
brake of FIG. 1 in an operative position with the
parking or maxi brakes applied, the brakes being
in misalignment or misad~ustment such that an
indicator shows "red" when the brakes are
applied, and retracts when the brakes are not
applied.
30 FIG. ~ is a cross-sectional view of a diaphragm spring
brake of FIG. 1 in a operative position with
brakes applled, the brakes being in misalignment
or mi8ad~ustment such that an indicator is fixed
in position to show "red".
FIG. 5 is a cross-sectional view of a diaphragm spring
brake with the parking or "maxi" brake applied,
the brakes being in misalignment or misadjustment
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2 ~ 7
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such that an indicator is fixed in position to
show "red" continuously.
FIG. 6 is a elose-up cross-seetional view of a portion
of a diaphragm spring brake of FIG. l in an
operative position with brakes applied, the
brakes being in misalignment or misadjustment
such that an indieator shows "red" temporarily
when the brakes are applied, and retracts when
lo the brakes are not applied.
FI~. 7 is a close-up eross-seetional view of a portion
of a diaphragm spring brake of FIG. 1 in an
operative position with brakes applied, the
brakes being in misalignment or misadjustment
sueh that an indieator is fixed in position to
show "red" eontinuouely.
DBBCRIPTION OF THE PREFERRED EMBODIMEN~8)
A brake wear indieator for an air-aetuated
diaphragm spring brake system will now be diseussed with
referenee to the drawings which show an air-actuated
diaphragm epring brake actuator, of a conventional type,
for mounting on the axle of a vehicle and for connection
with, and actuation of, a vehicle braking system.
Referring initially to FIG. l, an air-actuated
diaphragm spring brake actuator is shown in cross-section
generally at 10. Actuator 10 generally comprises brake
housing 12 aeting on push rod 14 to move push rod 14
between an inoperative poeition wherein the brakes o~ the
vehiele are not applied (ehown in FIG. 1) and an operative
position in whieh the pueh rod 1~ extends ~rom housing 12
wherein the brakes are applied (as ehown in FIG. 2).
Housing 12 and push rod 14 are conventional
eomponents found on standard air-actuated diaphragm spring
` 2084~7
_5_
brake actuators, and have been modified to accommodate the
additional components of the invention as described herein.
Housing 12 is comprised of three components,
upper housing assembly lC, connecting housing assembly 18
and lower housing assembly 20 joined together. Assembly 16
is connected to assembly 18 about their respective outer
peripheries to form upper cavity 38. Upper diaphragm 3c,
described below, divides cavity 38 into upper cavity
chamber ~o and lower cavity chamber ~2. Upper clamp
assembly 22 extends about the periphery of assemblies lC
and 18 to securely sandwich upper flange 2~ and upper
connecting flange 2C with the outer periphery of diaphragm
36 therebetween, to form an airtight lower cavity chamber
~2 in the space enclosed by assembly 18 and diaphragm 36.
A~embly 20 is connected to assembly 18 about
their respective outer peripheries to form lower cavity 46.
Lower diaphragm ~, described below, divides cavity ~6 into
upper cavity chamber ~8 and S0 (seen best in FIG. 2).
Lower clamp assembly 28 extends about the periphery of
assemblies 18 and 20 to securely sandwich lower connecting
flange 32 and lower flange 3~ with the outer periphery of
diaphragm ~ therebetween to form an airtight upper cavity
chamber 48 in the space enclosed by assembly 18 and
diaphragm ~.
Upper diaphragm 36 is made of resilient flexible
material and is attached within cavity 38 formed within
assemblies 16 and 18. Diaphragm 36 forms an airtight seal
to divide cavity 38 into upper and lower cavity chambers ~0
and ~2 respectively. Diaphragm 36 i~ sandwiched between
flange~ 2~ nnd 26 to form an airtight ~eal and to maintain
the outer periphery of diaphragm 3~ between assemblies 16
and 18. Upper clamp assembly 22 provides clamping pressure
on flanges 2~ and 26 to maintain diaphragm 36 between said
flanges. Diaphragm 36 is flexible to move within cavity 38
.
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between an upper position, as shown in FIG. 1, and a lower
position adjacent top portion 31, as shown in FIG. 5.
Similarly, lower diaphragm 44 divides lower
cavity 4C formed and defined by bottom portion 30 and lower
housing assembly 20. Diaphragm 4~ is sandwiched between
flanges 32 and 34 to form an airtight seal bisecting cavity
4C. Cavity 4C is thereby divided into upper cavity chamber
48 and lower cavity chamber 50; best seen in Figures 2 and
3. Diaphragm 4~ is made of resilient material and is
flexible to move within cavity 46 to a position adjacent
the inner wall of bottom portion 30 (as seen in FIG. 1) and
a maximum lowered position substantially adjacent lower
housing assembly 20 (as seen best in FIG. 4).
Connecting housing wall 52 separates cavities 38
and 46. Upper push rod 54 is positioned for reciprocal
movement within cavities 38 and 46 through opening 56 in
wall 52. Push rod 54 includes upper flange S8 attached
laterally at the upper side ad~acent diaphragm 36 and lower
flange 58 attached to the lower end of push rod S4 adjacent
the upper side of diaphragm 44. When push rod 54 is in its
upper or inoperative position, as shown on FIG. 1, lower
flange 60 seats within conforming cavity 62 in wall 52. An
airtight seal is formed between push rod 5~ and opening 56
by means of rubber 0-ring 64 which permits slidable
movement of push rod S4 between its upper (inoperative) and
lower (operative) positions without air leakage through
opening 56. Push rod 5~ is shown in its upper position in
FIG. 1 and in its lower position in FIG. 3.
Compression ~pring 66 is positioned within
chamber 40 with one end contacting inner wall of top
portion 68 of assembly 16. The other end of spring 66
contacts compression pressure plate 70 which iB movable
within cavity 38 on expansion and contraction of spring 66.
Diaphragm 36 is sandwiched between pressure plate 70 in
chamber 40 and by flange 58 in chamber 42. Compression
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-7-
spring 66 biases pressure plate 70 toward connecting
housing assembly 18 thereby biasing flange 58 and push rod
5~ to the lower or operative position, as shown in FIG. 3.
Compression return spring 72 is attached to the
lower end of flange 58 at one end and to the upper side of
wall 52 at the other end. Spring flange 74 on wall 52
constrains compression return spring 72 between flange 7~.
Return spring 72 biases flange 58 to the upper position as
shown in FIG. 1. The upward bias force of spring 72 is
less than the downward biasing force of spring 66 and
sufficient air pressure is required in chamber 42 in order
to asset spring 72 to overcome the biasing force of spring
66 to move spring 66 to its compressed position as shown in
FIG. 2.
Push rod 1~ extends from inside lower cavity ~6
at an upper end out opening 102. The lower end of push rod
1~ extends out o~ cavity ~6 through opening 102 and has a
threaded end 9~ for receiving clevis locking nut 80, to
which clevis assembly 82 is attached. Clevis assembly 82
is connected to the braking system (not shown) of the
vehicle. When actuator 10 i8 in the inoperative position
rod 1~ is in its upper position and the brakes are not
2S applied. When actuator 10 actuates the brake system rod 14
moves downward until brake contact is made to apply the
brakes of a motor vehicle.
Push rod plate 76 extends from the upper end of
push rod 1~ in a lateral direction. Plate 76 is circular
and substantially similar in shape to the bottom side of
wall S2. Push rod return spring 78 i5 positioned within
lower cavity chamber 50 with one end ad~acent the lower
~ide o~ plate 76 and the other end ad~acent wall 100 o~
lower housing a~sembly 20. Spring 78 biases plate 76 to
the upper position, as shown in FIG. 1. Spring 78 thereby
biases diaphragm ~ to its upper position through pressure
on diaphragm 4~ by plate 76.
-8- 20~4~7
The upward bias force of spring 78 is less than
the downward biasing force of spring 66 and sufficient air
pressure is required in chamber ~2 such that spring 72 may
move push rod 5~ to its upper position, in order to permit `
spring 78 and attached plate 76 to move diaphragm ~ to the
upper position (FIG 2.). As well, when spring 66 is
extended to its extended position (as shown in FIG.3),
thereby pushing push rod 5~ to the lowered position, spring
78 is compressed to its retracted position against the
biasing force of spring 78. Concurrently, spring 72 is
compressed to its retracted position against the biased
force of spring 72.
The visual inspection sleeves encircling push rod
1~, will now be discussed with reference to FIGS. 1 and 6.
Electrical contact sleeve 8~ encircles push rod 14 and is
po~itioned ad~acent plate 76. As ~een in FIG. 6, sleeve 8~
is tapered with the larger end ad~acent plate 76 narrowing
to a smaller diameter end opposite plate 76. Contact
sleeve 8~ is made of bronze and will conduct electricity to
indicate a hazardous brake condition, as will be
hereinafter described. Danger indication sleeve 86
encircles push rod 1~ adjacent sleeve 8~. Sleeve 86 has a
similar outer circumference as the end of sleeve 84
ad~acent sleeve 86. Sleeve 86 is red in color to provide
visual indication of a dangerous brake condition. Caution
indication sleeve 88 is positioned adjacent sleeve 8C and
is of similar diameter as sleeve 86. Caution sleeve 88 is
yellow in color and provides a visual indication of
predetermined intermediate brake wear which alerts the
operator to the potential of future dangerous brake
condltion 80 that appropriate ad~ustment or repair may be
undertaken be~ore a dangerou~ condition occure. Sa~e
indication sleeve 90 encircles push rod 1~ ad~acent sleeve
88. Sleeve 90 is of similar diameter as sleeve 88. Sleeve
90 is green in color to provide a visual indication of safe
brake condition. Spacer sleeve 92 encircles push rod 1
adjacent sleeve 90. Sleeve 92 is of similar diameter as
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sleeve 90. Sleeve 92 acts as a spacer between safe
indication sleeve 90 and washer 9~ which retains sleeves
8~, 86, 88, 90 and 92 in juxtaposition against plate 96.
Sleeves 9C, 98, 90 and 92 are made of plastic or other
non-conductive materials. Washer 9~ is held tightly
against sleeve 92 by nut 96 threaded onto threaded portion
98 of push rod 1~
The outer diameter of sleeves 8C, 88, 90 and 92
are similar to form a relatively smooth outer surface to
optimize sliding of the sleeves and rod 1~ past ring 11~
and surface 122 as rod 14 is moved between its operative
and inoperative positions. As well, smaller diameter end
o~ sleeve 8~ is generally of the same diameter of adjacent
sleeve 8C to optimize sliding of push rod 1~.
Alternatively, sleeves 8~, 86, 88, 90 and 92 can be made of
unitary construction with coloured bands thereon to
correspond to the several sleeves discussed herein,
provided that the upper portion of such unitary sleeve is
of bronze or other electrical conducting material, and is
tapered, to correspond to sleeve 8~.
As will be appreciated by those skilled in the
art, the outer diameter of sleeves 86, 88, 90 and 92 may be
increased by enlarging opening 102 and the diameter of
inner surface 122 of ring 11~. Corresponding modification
o~ spring 78 may also be made to accommodate larger
diameter of sleeves 86, 88, 90 and 92 therein. Larger
diameter sleeves 86, 88, 90 and 92 facilitate ready visual
identification of the exposed colored surfaces of sleeves
86, 88 and 90.
The electrical connection for the remote danger
indicator 10~ will now be described with reference to
figures 1, 5, 6 and 7. The remote danger indicator 10~
provides either an audible or visual signal of a dangerous
brake condition, to the operator. The remote danger
indicator 10~ will operate intermittently to warn the
2 0 ~ 7
--10--
driver of dangerous brake wear or other dangerous brake
condition not yet severe enough to cause brake failure but
intended to warn the driver that the brakes need adjustment
or repair. The remote danger indicator 10~, when fixed in
place, remains activated on a continuous basis, providing
a continuous indication to the operator and others who may
wish to examine brake condition, of severe brake
misalignment or damage or complete brake failure. Once
fixed in place, the remote danger indicator 10~ cannot be
reset or turned off and provides continuous evidence that
severe brake misalignment, damage or failure has occurred.
Lower portion 100 of assembly 20 includes a
central openinq 102 therethrough, through which push rod 1~
and attached sleeves 8~, 86, 88, 90 and 92 extend and
retract and in which remote danger indicator 10~ is fitted.
Opening 102 has been enlarged from the
pre-existing opening of a standard brake actuator designed
to accommodate only rod 1~. As best seen in FIG. 6, steel
ring 10C is welded about the circumference of opening 102
by weld 108. Ring 106 is constructed of steel and will
conduct electricity when a current is applied. Red plastic
indicator ring 110 fits within ring 106 and is held in
place at the top of ring 106 by breakable protrusion 112.
Inner black plastic indicator ring 11~ is attached to ring
110 along connecting surface 116 adjacent ring 110. Lip
118 of ring 11~ extends below ring 110 and a portion of
ring 106 preventing movement of ring 11~ and ring 110
upwardly into cavity chamber S0.
Copper wire 120 is connected to the negative
terminal of the standard DC wiring system of the vehicle,
or i~ attached to ground, as ~or example ring 106 as shown
in FIG. 6. An intermediate portion of wire 120 extends
along surface 116 over the top of ring 11~. Wire 120 then
extends downwardly between the inner surface 122 of ring
2.1~ and the outer surface of sleeves 8~, 86, 88, 90 and 92
on push rod 1~ as push rod 1~ is moved adjacent surface
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2 0 ~ 7
122. Wire 120 contacts the outer surface of the sleeves as
push rod 1~ is moved between its extended and retracted
positions.
Copper wire 12~ is connected to the positive
electrical system of the motor vehicle at one end and
extends along surface 116 in an area generally opposed to
wire 120, in an upward direction into chamber 50. Contact
section 126 of wire 12~ extends outwardly along outer
surface 128 of ring 110 above protrusion 112. Wire 12~
then extends inwardly to wrap about the top of ring 11~ and
then downwardly along surface 122 in an area generally
opposite to wire 120 to contact sleeves 8~, 86, 88, 90 and
92 as push rod 1~ is moved between its extended and
retracted positions.
Referring to FIG. 7, when indicator 10~ is moved
to the fixed position, ring 110 is forced downward by
excessive downward movement of push rod 1~, which causes
plate 76 to contact the upper surface of rings 110 and 11~
thereby pushing protrusion 112 against ring 106 and
breaking protrusion 112 off. This downward pressure jams
the broken surface left when protrusion 112 is broken off,
securely against the inner surface of ring 106, thereby
securing indicator 10~ in a lowered position secured to
ring 106 ~shown in FIG. 7). Outer indicator surface 130,
which is red in color, is also simultaneously exposed to
view below portion 100 to provide visual indication of the
fixing o~ indicator 10~. At the same time, contact section
126 is jammed into position to contact ring 106 which
thereby grounds wire 126 to cause current to ~low to the
remote audible or vl~ual lndicator ln the cab of the
vehicle.
When push rod 1~ is extended outwardly from
portion 100 past a predetermined point, wires 120 and 12~
contact sleeve 8~ which is bronze and which conducts
electricity. This causes an electric circuit to be
,, , . . , : , . . .
" , ~:,
-12- 20~ 7
completed and the visual or audible indicator to be
actuated in the cab of the vehicle, thereby alerting the
driver of a dangerous brake condition which should be
repaired. Until ring 110 is fixed against ring lOC,
S release of actuator 10 and corresponding upward movement of
rod 14 and sleeve 8~, will break the circuit and cause the
remote indicator to turn off.
Rings llo and 11~ are prevented from further
outward movement beyond a maximum predetermined point, by
lip 132 of ring 110 which contacts ring 106 on maximum
downward movement of rings 110 and 11~.
Air is supplied into chamber ~8 through conduit
lS 1~2, when the operator wishes to apply the brakes by
pre~sing the brake peddle of the vehicle. Air pressure on
diaphragm ~ causee diaphragm ~ to push plate 76 and push
rod 1~ downwardly to apply the breaks of the vehicle. Air
ie introduced into lower cavity chamber ~2 through conduit
1~ to provide sufficient air pressure within chamber ~2 so
as to permit spring 72 to bias spring 66 into its
compressed position as shown in FIG 1. In this position
the parking or maxi break is in the inoperative position.
A further conduit 1~6 is provided into chamber ~2 to
releaee air pressure from chamber ~2 when the operator
wishes to activate the parking or maxi break. Upon release
o~ air pres~ure, spring 66 biases plate 70 downwardly
against spring 72 to compress spring 72 as shown in FIG. 3,
thereby causing pueh rod 1~ to move to the operative
position to apply the vehicle brakes.
Actuator 10 ie mounted in a conventional way to
the appropriate axle o~ a vehicle by meane of nut 13~,
waeher 136 and bolt 138 connected to portion 100 of
actuator 10. Assembly ~2 is connected to the brake
assembly of the motor vehicle for inward and outward
reciprocal motion with corresponding inward and outward
reciprocal motion of push rod 1~. Rubber stopper 1~0 is
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.
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.
: . - ........... :
, . . . . . .. , . ., :. , : -
20~4~
-13-
connected to the top of bolt 138 to act as a bumper to
prevent further downward movement of plate 76 beyond a
maximum predetermined distance.
OPERATION
FIG. 1 shows actuator 10 in an inoperative
position, as when both the foot pedal brake and the parking
brake are not applied by the operator. Air flows through
conduit 1~ into cavity 38 to create positive pressure in
cavity 38. This pressure, together with biasing pressure
of spring 72, overcomes the opposite biasing pressure of
spring CC to compress spring 6C and move plate 70 and
diaphragm 3C upwardly toward spring CC. Spring 72 also
maintains push rod S~ in the upper position which permits
spring 78 to bias plate 76 in the upper or retracted
position, thereby maintaining push rod 1~ in the upper
position. The brakes of the vehicle (not shown) are then
in an inoperative position with no braking pressure
applied.
Referring to FIG. 2, when the brakes are in
proper adjustment, on application of the foot brake by the
vehicle operator, air pressure is introduced through
conduit 1~2 into upper cavity chamber ~8 thereby forcing
diaphragm ~ and plate 7C downwardly. This forces push rod
1~ out until brake contact is made, thereby applying the
brakes. When the brakes are properly adjusted push rod 1~
will extend, and brake contact will be made, somewhere in
the zone which exposes safe indication sleeve 90 in view,
beyond the bottom edge o~ ring 11~, thereby expo~ing green
~leove 90 to physical inspection. Alternatively, i~ the
operator wishes to "test" the brakes, he can simply insert
a pry bar in the usual manner to pull out push rod 1~ until
brake contact is made. He can then observe the sleeves to
determine that sleeve 90 has been exposed in the manner
described above, thereby indicating that the brakes are in
proper adjustment. As the brakes go further and further
' ,~ ,: ,.~. ,.' '~ ''' " ' '' ' ',,,, ;
. . ..
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. . .. .. .
- 2 0 ~ ) 7
-14-
out of adjustment, which occurs through normal wear of the
brakes, more and more of push rod 1~ will be exposed beyond
ring ~1~. Eventually, caution indication sleeve 88,
colored yellow, will be exposed to view. Sleeve 88 is
positioned along push rod 1~ to be exposed when brake wear
is such that either brake adjustment or brake repair is
required.
Referring to FIG. 4, as brake wear increases or
as the brakes go further out of alignment, the travel of
push rod 1~ increases in order to cause brake contact. In
an extreme situation, where total brake failure has
occurred, air pres~ure through conduit 1~2 will cause
diaphragm ~ to push plate 76 until contact with bumpers
1~0 occurs. This forces ring 11~ downwardly until lip 132
contacts ring 106. This downward movement also breaks off
protrusion 112 thereby fixing ring 11~, with respect to
ring 106, with surface 130 exposed. Evidence of such brake
failure is thereby fixed and remains so, while push rod 1~
and adjacent sleeves are retracted as the brakes are
released and air pressure in chamber ~8 decreases causing
return spring 78 to expand to the position shown in FIG. 1.
Even with the retraction of push rod 1~, indicator 130
remains exposed and the remote visual or audio indicator
remains continuously actuated.
Referring to FIG. 3, the operator can also
actuate the brake system by using his parking or maxi
brake. On operation of the maxi brake actuator, air
preesure in chamber 38 is released to atmosphere which
enables spring 66, through downward biasing pressure, to
act against spring 72 to move plate 70 downwardly. This
also moves pu~h rod~ 1~ and 5~ downwardly applying the
brakes. With excessive brake wear, danger indication
sleeve 86 is exposed to view by the operator on application
of the parking brake, thereby exposing the color red to the
operator's view alerting the operator to a dangerous brake
condition. It can be appreciated that movement of push rod
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1~, and sleeves 8~, 86, 88, 90 and 92 will occur either on
foot brake actuation or parking brake actuation by the
operator, due to the conventional operation of actuator lo.
On push rod 1~ being extended to a dangerous
brake condition actuation of the audible or visual remote
indicator will occur through contact of wires 120 and 124
with bronze sleeve 8~, thereby completing the circuit and
actuating the remote indicator.
~:
When a predetermined severe brake misalignment or
complete brake failure has occurred, plate 7C will contact
rings 110 and 11~ causing protrusion 112 to break off and
~amming rings 110 and 114 securely against ring lOC. This
also causes contact section 126 to contact ring lOC thereby
completing a circuit and causing continuous actuation of
the remote visual or audio indicator. Thus, even when push
rod 1~ and the corresponding sleeves thereon are moved
upward through return spring pressure caused by spring 78,
as when the foot brake or max~ brake are released, the
remote visual or auditory indicator remains actuated and
visual indicator surface 130 remain exposed as a constant
indication that severe brake misalignment or failure has
occurred.
