Note: Descriptions are shown in the official language in which they were submitted.
1~)47417
,
Backqround of the Invention
Conventional rail car brake apparatus has for many
years comprised a pair of transversely extending, brake shoe
carrying brake beams supported for sliding motion by the rail
car truck, particularly in freight car applications. Air driven
actuators mounted between the beams, to the rail car bolster or
- to the car body itself have been used for moving the brake beams
` as required to effect movement of the brake shoes into braking
position against the wheels of the truck. one such prior art
is shown in U.S. Patent 3,621,941 to Blout.
: Although this type of brake apparatus has received con-
. .................................................................... .
siderable attention over the years, a variety of problems have
remained unsolved. The greatest single unsolved problem in prior
art systems is the maintainability of the four requisite brake
cylinders at required cleaning intervals. Another recurrent - -
problem is that of maintaining the overall weight of the brake
rigging as low as possible, consistent with providing adequate
structural strength to sustain the considerable loads generated
in the rigging during braking. In freight car applications
having truck mounted brakes, the brake beams are heavy ductile
iron castings of great weight having integral brake heads.
Clearly, the great mass of these elements adds to the total car
weight and thus reduces proportionately the maximum payload
which the car can carry for a given axle load. The design of a
truck mounted brake must account for uneven wear of the brake
shoes which may cause the beam ends on one side of the car to
move further during brake application than on the other side.
ln474i7
`
This, in turn, may induce undesirable side loads in conventional
piston and cylinder brake actuators due to the inflexibility of
these actuators, and requires the use of a hollow rod for the
piston and a flexible push rod in order to provide the requisite
flexibility. ~-
Variations in truck geometry may also occur since rail-
way car trucks are designed to include a certain amount of in-
herent flexibility, which allows for some departure from the
normal rectangular configuration of the truck, or "parallelo-
s~
gramming." This flexibility has been found to be essential in
maintaining the stability of the truck and its ability to stay
,
or remain on the rails at high speeds and to negotiate curves,
crossovers and switches in railway tracks. In addition, this
r~ flexibility helps to minimize wear of the flange and tread of
;~ the truck wheels. Thus, while maintenance of this flexibility
is important for overall rail car performance, the movement of
truck components cause corresponding movements of the brake
rigging which must be taken up by provision for flexibility in
the rigging itself.
- 20 Obiects of the Invention
An object of the invention is to provide a rail car
brake system which does not require periodic cleaning, due to the
absence of a piston and its associated seals.
A further object of the invention is to provide a rail
car brake system of substantially reduced weight relative to
prior art systems.
Another object of the invention is to provide an im-
proved brake beam of sheet metal construction, having means to
facilitate installation and removal of brake heads, brake
~ 1~34'~4i`7
actuators, and related equipment and being particularly a-
dapted to replacement of prior art beam and brake cylinder
assemblies without requiring modification of the truck mounts,
- handbrake actuators and related equipment.
- A further object of the invention is to provide an air-
... .
-.~ operated brake actuator comprising means for accomodating
movement of the brake beams due to changes in truck geometry
~- while ensuring adequate brake force transmission from the
actuators to the beams.
Yet another object of the invention is to provide animproved
~ air-operated brake actuator comprising an expansible flexi-
'#' ble bellows for transmitting air pressure to the brake.
Still another object of the invention is to provide a
brake actuator having sufficient flexiblity and long stroke,
, so as to eliminate the need for a mechanical slack adjustor.
.
.,:
These objects of the invention are only exemplary of
the applicant's intentions in developing the invention; thus,
it may be that other objects or desirable goals inherently
attained by the invention will occur to those in the art.
It should be understood, however, that the scope of the in-
vention is to be limited only by the appended claims.
Summary of the Invention
At least some of the above objects of the invention are
achieved by a fluid pressure operable actuator suitable for
use in a railway vehicle brake system, comprising mounting
plate means for attaching said actuator to adjacent structure;
a flexible bellows sealingly attached at one end to said
mounting plate means; an actuator piston sealingly attached
-3-
. .
15~47~17
i to the other end of said flexible bellows; push rod means
.`: attached to said actuator piston for transmitting motion of
. . .
.` said actuator piston to said brake system; means for pres-
surizing the interior of said bellows to effect motion of
r:- ~ said actuator piston; and means operatively interconnecting
said mounting plate means and said push rod means for con-
,.. .
fining motion of said push rod means and said actuator piston
to paths extending radially from a reference point fixed rel-
; .
'.; ative to said mounting plate means.
,-;
Other objects of the invention are achieved by a brake
:~ beam suitable for use in a railway vehicle brake system,
~ comprising an elongated, hollow beam body member having up-
., .
. per and lower spaced walls; access port means oppositely lo-
;. cated in said spaced walls; and actuator mounting plate means
.- attached between said spaced walls along opposing edges of
said access port means.
: Still other objects of this invention are achieved by
~ a brake apparatus suitable for use in a railway vehicle com-
: prising in combination a pair of brake shoe carrying beams
adapted to be movably mounted in the vehicle truck; and a
fluid pressure operable actuator mounted to each beam of
said pair, said actuator comprising a mounting plate attaching
the actuator to its beam; a flexible bellows sealingly attached
at one end to said mounting plate means; an actuator piston
sealingly attached to the other end of said flexible bellows;
push rod means attached between said actuator piston and the
opposite beam for transmitting motion of said piston to the
opposite beam of said pair; means for pressurizing the in-
: -4-
` ~1474~7
terior of said bellows to effect motion of said actuator
piston; and means operatively in~erconnecting said beam,
said mounting plate means and said push rod means for con-
fining motion of said push rod means and said actuator pis-
ton to paths extending radially from a reference point fixed
relative to said mounting plate means.
Brief Description of the Drawings
FIG. 1 shows a perspective view of a type of prior art
brake apparatus comprising cast brake beams and dual, double-
acting brake actuators.
.
FIG. 2 shows a perspective view of a brake apparatus
according to the invention comprising fabricated brake beams
and dual, single-acting pneumatic bellows actuators and as-
- sociated handbrake actuating linkages.
FIG. 3 shows a perspective view, partially exploded and
partially in section of a fabricated brake beam according
to the invention.
FIG. 4 shows a view, partially in section, taken along -
line 4-4 of FIG. 2 showing the unique pneumatic bellows actu- - -
ator according to the invention.
Detailed Description of the Preferred Embodiments
There follows a detailed description of both a type of
prior art brake apparatus and the improved brake apparatus
according to this invention, reference being had to the at-
tached drawings, wherein like reference numerals depict like
elements of structure in each of the several Figures.
FIG. 1 shows a perspective view of a brake beam assembly
10 of a type known in the prior art. Assembly 10 comprises
1~47417
., ..:
' brake beams 12 and 14 which are usually ductile iron castings
having integral brake headsl6. Mounted on brake heads 16
are replaceable brake shoes 18. Mounted on each of brake
; beam~12 and 14 are air-actuated piston and cylinder motors
20 from which extend push rods 22 which are respectively at-
i~ tached to each of brake beams 12 and 14 by pin joints 24, as
indicated. A handbrake actuating linkage is also provided.
~; Handbrake fulcrum brackets 26 may be attached on the left
::
hand end of the brake beams as viewed in Figure 1 or, alter-
nately, may be attached at location 28 on the right hand endof the beams, as desired for a particular application. Piv-
otally attached to handbrake fulcrum brackets 26 are elon-
gated handbrake levers 30. The lower ends of handbrake
' levers 30 are pivotally connected by handbrake connecting
rod 32 which extends through safety straps 34 located on
. .
each of brake beams 12 and 14. Safety straps 34 serve to
prevent handbrake connecting rod 32 from dropping into con-
~,~ tact with the railway bed in the event that one end of the
connecting rod 32 should work loose from its handbrake lever.
:~,
The upper ends of handbrake levers 30 are pivotally connectedto clevises 36. On one beam, clevis 36 is attached to the
handbrake anchor connecting link (not shown) and on the other
- beam to the handbrake actuating chain or rod (not shown), in
accordance with usual practice. A more detailed description
of this prior art system is found in General Letter No. 377
of December 5, 1966, published by The New York Air Brake
Company.
This prior art type of brake assembly is suitable for
-6-
':
1[)47417
;........................................................................ .. ..
installation to a unit beam railcar truck in such a manner
, that a single shoe brake is applied to each wheel of the
freight car. On some cars it is only necessary that the
trucks have unit beam side frames and a truck bolster with
~ suitable openings for the push rods to pass through. This
.'
type of brake assembly combines the functions of the piston
i,
and cylinder motors, brake rigging, and brake beams into a
compact arrangement such that the piston push rod pushes
directly on one brake beam while the cylinder itself pushes
directly on the other brake beam. The resultant doubling of
the motor force by using both the piston push rod thrust and
the cylinder reaction permits the use of somewhat smaller
piston and cylinder motors compared to other types of brake
assemblies, and results in more effective equalization of -
brake shoe pressures at all wheels. These types of brake
assemblies are designed for use with the conventional AB and
ABD brake systems in combination with high friction composition
brake shoes. Although this type of prior art system has been
. , .
in service for some time, it does have the disadvantages of
high maintenance cast for periodic cleanings and substantial
; weight in the cast brake beams.
FIG. 2 shows a brake beam assembly with pneumatic bel-
lows actuators according to the present invention. The
,~ brake mechanism of this invention has been designed to facil-
itate installation in rail cars of the type adapted to ac-
cept prior art brake systems of the type discussed with re-
spect to Figure 1. The fabricated brake beam assembly and
bellows actuators, indicated generally at 50, comprise a
~,
, ,, . . .. :
:` lQ47417
, ,~;
pair of fabricated brake beams 52 and 54 having attached
thereto by welding or other suitable means,
brake heads 56 which are of the same general configuration
:, .
as the prior art brake heads. Attached to the brake heads
,.
56 are replaceable brake shoes 58 which likewise may be
.~
identical to those used in the prior art. Mounted to each
fabricated brake beam 52 and 54 is a pneumatic bellows actu-
;. .~
ator 60 from which extends a push rod 62 which is connected
~ .
by a flexible joint 64 or other suitable means such as a
- 10 clevis and pin to the opposite fabricated brake beam. A
~- handbrake fulcrum bracket 66 of the type used in the prior
:,;
;~ art system may be attached at the left side of the brake
mechanism as indicated or, alternately, may be attached at
. .
location 68 on the right side of the brake mechanism, as
~:
desired. Handbrake levers 70 are pivotally attached to
;.,
handbrake fulcrum brackets 66 and to handbrake connecting
rod 72, as previously discussed. Safety straps 74 prevent
a loose connector rod from dropping to the railway bed and
clevises 76 may be attached to the anchor connecting link
' 20 (not shown) or handbrake actuating chain or rod (not shown),
.,-,
, in a manner similar to that known in the prior art.
Briefly, in operation, the pneumatic bellows actuators
~; 60 are pressurized from the conventional air brake actuating
.
system thereby causing the actuators to expand and apply
brake actuating force symmetrically to the brake heads 56
attached to each brake beam. Upon depressurization of the
pneumatic bellows actuato~60, the brake beams return to
their initial position, due to the influence of gravity
,,
--8--
, . .. . . . . .
.
~ 1()47~17
~.
acting on the brake beams.
When a handbrake actuation is desired, actuating force
is applied to one of clevises 76 and transmitted via con-
necting rod 72 to the opposite handbrake lever 70. Since the
upper end of the opposite handbrake lever 70 is fixed to the
anchor connecting link (not shown), this opposite connecting
- rod will rotate about its clevis 76 until the brake shoes
attached to its beam are brought into contact with their
respective wheels. As soon as brake contact is made at the
opposite side, the remaining handbrake lever pivots about
its lower end in response to the actuating force to bring
the brake shoes attached to its beam into contact with their
"
., .
respective wheels. The handbrake lever 70 may be disposed
vertically, as indicated, or at an ang~le with the vertical.
Clearance between the railcar body and the handbrake levers
will determine which orientation of the handbrake levers is
~ to be used.
i The simple parallelogram arrangement of handbrake levers
~, ~
70 allows some truck pivoting without inducing changes in
shoe forces or clearances. One corner of the lever parallel-
ogram is attached to the car body by the anchor connecting
link and the other corner of the parallelogram is attached
to the handbrake chain or rod. When the truck pivots on
the car body, the top of one lever is pulled while the top
of the other lever is pushed an equal distance, which per-
mits the pivot points at the handbrake fulcrum brackets to
remain in essentially one position and prevents transmission
of force to the brake shoes.
_g_
~;
-
1~47~7
.
FIG. 3 shows a perspective view, partially exploded andpartially in section, of a brake beam according to the in-
vention. The brake beam body 100 is of generally U-shaped,
hollow cross-section, as shown, and comprises an elongated
vertical compression wall member 102 from which extend spaced,
horizontal upper and lower walls 104 and 106, of generally
assymmetrical trapezoidal configuration. Body 100 may be
`~ stamped from a single sheet of stock and bent to the illu-
strated configu3~ation, or may be assembled from separate
sheet elements suitably welded or otherwise joined. Brake
head mounting slots 108 are formed by the opposite ends of
elements 102, 104 and 106 to provide a point of attachment
for cast brake heads 56. Brake heads 56 are attached to
beam body 100 by plug welds made through plug weld holes 110
in upper and lower walls 104 and 106 and by a peripheral weld
applied between brake head 56 and the edges of elements 102,
104 and 106 and weld preparation 112 located on each brake
.:
head.
- Upper and lower wall elements 104 and 106 include long,
angled edges 114 and short, angled edges 116 which rise from
the area of brake head mounting slots 108 and join edge 118,
which is essentially parallel to compression wall member 102.
A cover plate 120 is welded to edges 114, 116 and 118 as in-
dicated and extends along angled edges 114 and 116 to the
location at which the handbrake attachment is to be made.
The angled edges 114 and 116 and cover plate 120 coact as the
ten~ion carrying element of the beam according to the inven-
tion.
--10--
,
,
-- ln474l7
~: A handbrake mounting pocket 122 is provided for hand-
brake fulcrum brackets 66 and comprises a cast or forged
' block 124 having a weld preparation flange 126 attached there-
.
; to to facilitate attachment to edges 114 and 116. slock
-~ 124 further comprises a pocket bore 128 and a fastening pin
~ bore 130. Bore 130 is sized and located to mate with holes
~,
;'?' 132 provided in upper and lower walls 104 and 106. The hand-
.~ brake fulcrum brackets 66 may thus be inserted into pocket
,. bores 128 and secured by means of a pin extending through
; 10 holes 132 and bore 130.
Located oppositely in upper and lower walls 104 and 106
are mounting and access ports 134 which include at least one
flat edge 136 oriented essentially parallel to compression
;~ wall member 102 and edges 118. An actuator mounting plate
138, of generally circular configuration is provided, in-
:~.
;: cluding a rectangular boss 140 sized to be received between
~.
~. upper and lower walls 104 and 106 within mounting and access
"' ports 134, as more clearly indicated in Figures 2 and 4.
,!1,
Mounting plate 138 is then welded to flat edges 136 within
access ports 134 to provide a rigid point of attachment for
pneumatic bellows actuators 60. Provision of access ports
134 facilitates installation and removal of the actuators 60.
Cooperation among mounting plate 138, edges 136, upper and
lower walls 104 and 106, and cover plate 120 ensures rel-
atively uniform distribution of tension forces in the area
of edges 114, 116 and 118 during operation.
Located in compression wall member 102 just opposite
mounting plate 138 is a through hole 142 which allows pas-
--11--
~ lQ47~17
" .
;- sage of push rod 62. A reinforcement ring 144 is welded to
,, ,
- the periphery as indicated. Also located in compression wall
`- 102 is through hole 148 which is located appropriately to
receive push rod 62 from the pneumatic bellows actuator 60
located in an opposite brake beam. A reinforcing ring 150
~; is welded to the periphery of through hole 148. Finally,
through holes 152 are provided in upper and lower walls 104
;~ .
s,,
and 106 in a location to receive joint bosses 154 which are
~, welded in place to provide an attachment point f~r flexible
~;.
`~ 10 joints 64 of each push rod, as indicated in Figure 2. The
weight of these beams for normal freight brake applications
. .
is substantially reduced compared to prior art cast beams.
. .
FIG. 4 shows a view taken along line 4-4 of Figure 2,
indicating the details of the pneumatic bellows actuator
, ,: .
~ according to the invention. A bellows mounting plate 160
;, .
is attached to mounting plate 138 by a single ball stud 166,
, having a threaded shank 167 and spherical head portion 169. -
~ .
Sealingly attached to mounting plate 160 is a pneumatic
~,' bellows or bag 162 which may be of suitable reinforced rubber
:.
^ 20 or other construction and may have one or more convolutions
- as desired. A pneumatic actuator piston 164 is sealingly at-
..
tached to the opposite end of pneumatic bellows 162. Ball
stud 166 is threadingly attached to mounting plate 138 through
a bore in mounting plate 160 as indicated. Pneumatic actu-
ator piston 164 comprises a central flange 170 to which is
sealingly attached a tubular push rod 172 at the center of
flange 170, in a location approximately centered on ball stud
166. Wall 171 of actuator piston 164 extends essentially
~.'
1~47~17
, coaxially with push rod 172 and includes an outwardly flared
: .
, portion 173 along which bellows 162 moves as piston 164 moves.
A guide tube 174 is pivotally attached to spherical head por-
..:
tion 169 of ball stud 166. Tube 174 includes at its outer end
' a split, dry lubricant ring or bearing insert 176 of a material
.. . .
such as glass reinforced Teflon, which provides smooth sliding
, .
contact within the inside diameter of tubular push rod 172.
The interior end of guide tube 174 also includes a similar in-
'~ sert 176A and is vented at 177 to the interior of pneumatic
~.i
, 10 bellows 162. The end of tubular push rod 172 opposite its
~ .,
,~ attachment point to ball stud 166 is sealed by cap 178 which
~,,
includes a tapped bore 180 threadingly receiving end 182 of
'; push rod 62. A lock nut 184 mounted on push rod 62 permits:
the length of push rod 62 to be adjusted as necessary to
accommodate variations from railcar to railcar. The opposite
~- end of push rod 62 includes a flexible joint 64 having a bore
~ .
188 therein for receiving a pin mounted through bosses 154
located in beam body 100, as shown in Figure 3. Joint 64
comprises a cylinder 190 of rubber or suitable resilient ma-
' 20 terial which is bonded within bore 192 in the end of push rod
62. Sleeve 194 defines bore 188. The use of rubber cylinder
~ 190 provides considerable flexibility. Bellows 162 seals all
';~ sliding parts from wear due to foreign material, thus ob-
viating the need for periodic cleaning.
The unique geometry of the pneumatic actuator shown in
Figure 4 provides considerable flexibility in the assembly
: and operation of the brake system according to the invention.
Due to the universal interconnection between guide tube 174
-13-
~' ~n47~l7
and ball stud 166, the end of push rod 62 including flexible
joint 64 may be moved about considerably in order to facilitate
.
its attachment to the opposite brake beam, and to permit angu-
lar motion of each beam relative to the other during brake
^, operation. During such movement, the guide tube 174 and
' tubular push rod 172 are constrained to movement radially on
, ...
paths extending from the fixed center provided by the joint
between ball stud 166 and guide tube 172. Similarily, during
use should the location of flexible joint 64 shift due to
relative motion between the two brake beams, the alignment of
ball stud 166, guide tube 174 and tubular push rod 172 will
be maintained.
:.,
In operation, this feature is of great significance.
As the interior of pneumatic bellows 162 is pressurized
through pneumatic fitting 196 pneumatic actuator piston 164
:, .
~; will be constrained to move radially outward along the ex-
terior of guide tube 174 and will always apply the full brake
application force established by the applied pressure and the
effective area of piston 164 to flexible joint 64 in the op-
posing beam. If the universal connection between ball stud
166 and guide tube 174 were not provided, pneumatic bellows
162 would have to bo laterally and axially restrained in some
manner in order to ensure that the force generated by pres-
surization of pneumatic bellows 162 would be applied to pneu-
matic actuator piston 164 rather than dissipated in random
distortion of pneumatic bellows 162. Thus, the pneumatic
bellows or bag 162 does not require any lateral stiffness
when used in accordance with the teachings of this invention.
-14-
:
""' ~n474l7
`- The brake actuator of the invention is capable of suf-
ficient piston stroke to eliminate the need for a mechanical
- slack adjustor, such as those found in many prior art systems.
~;
Piston travel of more than 5-1/2 inches is easily achievable,
, .,
for example, which is sufficient to provide 5/8 inch new shoe
clearance at all wheels, 7/8 inch shoe wear at all shoes, and
,i:
~ 1 inch wear of the diameter of all wheels, with 1-1/2 inches
i~ piston travel remaining. Thus, if inspection shows sufficient
shoe thickness remaining, piston travel will always be correct
even without a slack adjustor.
From the above description of the invention, it will be
' apparent to those skilled in the art that the invention pro-
vides a significant improvement over prior art brake systems
due to the elimination of heavy, expensive cast brake beams:
to the provision of a brake actuator having significant in-
herent flexibility to account for variations in truck geom-
etry from railcar to railcar and during operation; and to the
~i,i,
simiplication of the brake actuator by the elimination of
previously used piston and cylinder combinations and by the
,....
elimination of the need for any lateral restraints or lateral
' stiffness of the type previously found in some bellows actu-
ated brake systems.
Having described my invention in sufficient detail to
enable one skilled in the art to make and use it, I claim:
-15-
