U.S. patent application number 09/401885 was filed with the patent office on 2001-11-22 for collet style tread brake unit.
This patent application is currently assigned to Roland S. Moore. Invention is credited to MOORE, ROLAND S..
Application Number | 20010042660 09/401885 |
Document ID | / |
Family ID | 23589645 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042660 |
Kind Code |
A1 |
MOORE, ROLAND S. |
November 22, 2001 |
COLLET STYLE TREAD BRAKE UNIT
Abstract
A brake actuator for use in railway transit and similar vehicles
to adjust for wear of braking components located on such vehicles.
The brake actuator includes an externally threaded or serrated rod
having a longitudinal axis. Such brake actuator further includes
power and slack adjusting collets disposed on the rod and located
in respective housings disposed about the collets and rod. A yoke
member is disposed about and in engagement with the power collet
housing and a first axially translatable bearing is disposed on the
yoke member. A second fixed bearing is spaced from the axially
translatable bearing and a piston is disposed for movement in a
direction generally perpendicular to the longitudinal axis of the
rod. The piston has an integral fork-shaped wedge disposed
astraddle the threaded or serrated rod for movement to a location
between the bearings. The fork-shaped wedge is effective to axially
translate the first bearing, yoke member, power collet and rod in a
direction perpendicular to the direction of movement of the piston
and wedge when the wedge enters between and engages the
bearings.
Inventors: |
MOORE, ROLAND S.; (TAYLORS,
SC) |
Correspondence
Address: |
JAMES RAY & ASSOCIATES
2640 PITCAIRN ROAD
MONROEVILLE
PA
15146
|
Assignee: |
Roland S. Moore
|
Family ID: |
23589645 |
Appl. No.: |
09/401885 |
Filed: |
September 23, 1999 |
Current U.S.
Class: |
188/33 |
Current CPC
Class: |
F16D 65/54 20130101;
F16D 2125/66 20130101; B61H 15/0021 20130101; F16D 2125/12
20130101; F16D 2121/14 20130101; F16D 65/28 20130101 |
Class at
Publication: |
188/33 |
International
Class: |
B61H 013/00 |
Claims
I claim:
1. A brake actuator for use in railway transit and similar vehicles
to adjust for wear of braking components located on such vehicles,
said brake actuator comprising: a rod having a longitudinal axis
and at least one of an externally threaded and serrated surface
extending over a portion of said rod; a power and a slack adjusting
collet disposed on said rod and located in respective housings
disposed about said power and said slack adjusting collets and said
rod; a yoke member disposed about and in engagement with said power
collet housing; a first, axially translatable bearing disposed on
said yoke member; a second, fixed bearing spaced from said axially
translatable bearing; and a piston disposed for movement in a
direction generally perpendicular to said longitudinal axis of said
rod and having a fork-shaped wedge disposed astraddle said at least
one of said externally threaded and serrated surface extending over
said portion of said rod for movement to a location between said
bearings, said fork-shaped wedge being effective to axially
translate said first bearing, yoke member, power collet and rod in
a direction perpendicular to a direction of movement of said piston
and wedge when said wedge enters between and engages said
bearings.
2. The brake actuator, according to claim 1, wherein said power
collet has a tapered bearing surface and said housing containing
said power collet has a corresponding tapered bearing surface for
engaging said bearing surface of said power collet and for forcing
said power collet into clamping engagement with said rod when said
yoke member is axially moved by said fork-shaped wedge of said
piston.
3. The brake actuator, according to claim 1, wherein a forward end
of said slack adjusting collet and said housing containing said
slack adjusting collet is separated by a clearance corresponding to
a clearance provided between a brake shoe and a wheel of such
railway transit vehicle.
4. The brake actuator, according to claim 1, wherein said brake
actuator further includes a spring located between said yoke member
and an end wall of a housing of said brake actuator.
5. The brake actuator, according to claim 1, wherein said brake
actuator further includes a spring located between said piston and
said yoke member.
Description
FIELD OF THE INVENTION
[0001] The present invention relates, in general, to a pressure
responsive type brake actuator for use on railway, or other similar
type, vehicles and, more particularly, this invention relates to a
tread brake actuator having a power and a slack adjuster collet
which enable automatic slack adjustment using fewer operating
components.
BACKGROUND OF THE INVENTION
[0002] Currently used tread brake actuators employ a plurality of
brake adjusting components in the form of nuts, ratchets, clutches
and springs to compensate for wear of both the wheel tread and
friction material of a brake shoe. FIG. 3 of the drawings in the
present application is a cross sectional view of such type brake
actuator.
[0003] Another and older type tread brake actuator is shown in U.S.
Pat. No. 3,995,537 to Severinsson. In both of these devices, a
fluid responsive piston moves in a direction perpendicular to a
push rod that operates to apply brake shoes directly to tread
surfaces of railway vehicle wheels. Slack adjustments in the brake
unit of the Severinsson patent are manually made by a nut disposed
on components located outside of a housing containing the piston
and push rod of the brake unit. The disclosure of this patent is
incorporated herein by reference thereto.
[0004] U.S. Pat. No. 5,423,401 to Noah et al., which is assigned to
the assignee of the present application, discloses power and slack
adjuster collets located on a push rod of a disc type brake
actuator. The disclosure of this patent is also incorporated herein
by reference thereto.
SUMMARY OF THE INVENTION
[0005] The present invention uses collet structures, similar to
those disclosed in the Noah et al. patent, in a tread brake unit
and thereby eliminates the multiple components of currently
available tread brake units for adjusting for wear of brake
material and wheel surfaces. More particularly, the invention
employs two housing structures respectively located about the slack
adjuster and power collets. The power collet housing provides a
bearing surface that forces the power collet into engagement with
an externally threaded push rod when air pressure is received by a
brake applying piston. The slack adjuster collet and its housing,
which is fixed, have a clearance between them that corresponds to a
typical clearance provided between the brake shoe and wheel
surface. The push rod is translated by the power collet to apply
the brake shoe to the wheel surface and causes the slack adjuster
collet to move until the brake shoe engages the wheel surface under
a braking force or until the slack adjuster collet contacts its
housing. Such contact occurs when the distance the push rod must
travel to apply such braking force exceeds the original clearance
of the brake shoe and wheel. This contact causes the slack adjuster
collet to stop while the push rod continues to travel through the
slack adjuster collet and its associated housing. When air pressure
is released, the piston moves away from the brake applying position
under force of a spring and the housing of the power collet returns
to its original position due to the action of another spring. The
return action of the housing of the power collet pulls the power
collet in a rearward direction which pulls the push rod and slack
adjuster collet rearwardly until the slack adjuster collet contacts
its housing at the end opposite the brake applying end of the
housing. When contact is made the slack adjuster collet stops and
holds the push rod, thus preventing further rearward movement of
the push rod. The actuator is now adjusted to the increased brake
shoe/wheel surface clearance due to wear. If the power collet is
not in a fully retracted position it will continue to move after
the slack adjuster collet contacts its housing, as the power collet
is now free to slide on the push rod until the power collet housing
is in a fully retracted position.
OBJECTS OF THE INVENTION
[0006] It is, therefore, a primary object of the present invention
to use a slack adjusting collet similar to that of the above noted
Noah et al. patent in tread brake units in place of currently used
slack adjusting nuts, ratchets and clutches in order to
significantly reduce the number of slack adjusting components
required in a tread brake unit.
[0007] Another object of the present invention is to provide a
railway and/or other similar type vehicle fluid pressure operated
tread brake actuator having an improved collet style slack
adjusting mechanism which is significantly more maintenance free
than previously used slack adjusting components.
[0008] Still another object of the present invention is to provide
a railway and/or other similar type vehicle fluid pressure operated
tread brake actuator having an improved collet style slack
adjusting mechanism which is generally less expensive to
manufacture due to significantly reduced assembly time required
compared to the time required to assemble previously used tread
brake actuators.
[0009] Yet another object of the present invention is to provide a
railway and/or other similar type vehicle fluid pressure operated
tread brake actuator having a collet style slack adjusting
mechanism that does not require special equipment to install.
[0010] A further object of the present invention is to provide a
railway and/or other similar type vehicle fluid pressure operated
tread brake actuator having a collet style slack adjusting
mechanism that is lighter in weight than previously used slack
adjusters.
[0011] It is an additional object of the present invention to
provide a railway and/or other similar type vehicle fluid pressure
operated tread brake actuator having a collet style slack adjusting
mechanism that exhibits a long operating life.
[0012] In addition to the objects and advantages of the present
invention described above, various other objects and advantages of
the invention will become more readily apparent to those persons
skilled in the relevant art from the following more detailed
description of the invention, particularly, when such description
is taken in conjunction with the attached drawing Figures and with
the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a view partially in cross section of a prior art
type tread brake unit;
[0014] FIG. 2 is a view partially in cross section taken along the
lines II-II of the prior art type tread brake unit illustrated in
FIG. 1;
[0015] FIG. 3 is a cross sectional view of a currently available
tread brake actuator; and
[0016] FIG. 4 is a cross sectional view of a presently preferred
embodiment of the tread brake unit of the invention employing power
and automatic slack adjusting collets.
BRIEF DESCRIPTION OF A PRESENTLY PREFERRED EMBODIMENT
[0017] Prior to proceeding to the more detailed description of the
present invention, it should be noted that identical components
which have identical functions have been identified with identical
reference numerals throughout the different views illustrated in
the drawing Figures for the sake of clarity and understanding of
the invention.
[0018] Refer now to FIGS. 1 and 2 of the drawings. Illustrated
therein is a prior art type tread brake cylinder and unit,
generally identified by reference numeral 10. Such unit 10 includes
an exterior housing 12 containing a piston 14 provided with an
integral wedge 16 (FIG. 1). Wedge 16 is fork-shaped in that it has
two fingers, or legs 18, that straddle a brake applying rod 20,
commonly referred to as a push rod. Such legs 18 extend to
locations disposed adjacent diametrically opposed roller bearings
22 and 24. The fingers 18 of the wedge 16 have a front edge 21 that
is slanted, or angled (as seen on the left in the view of FIG. 1),
while the rear of the wedge 16 (as seen on the right in the view of
FIG. 1) has an edge 23 that is substantially perpendicular to the
axis of the push rod 20.
[0019] There is a drive sleeve 26 located on and directly engages
such push rod 20. Disposed on such drive sleeve 26 are opposed
integral bosses 28 on which roller bearings 22 are rotationally
mounted. This is best seen in FIG. 2 of the drawings. Similarly, a
set of roller bearings 24 are located one on each opposed side of
the push rod 20 and are rotationally mounted on bosses 30, also,
located on opposed sides of such push rod 20. Again, as best seen
in FIG. 2 of the drawings.
[0020] Bosses 28 are an integral part of drive sleeve 26 which is
mechanically connected to the push rod 20 in a manner such that
these bosses 28 and their associated roller bearings 22 are
translatable along the axis of the push rod 20. Bosses 30, on the
other hand, are fixed relative to such bosses 28. Such bosses 30
are an integral part of the tread brake cylinder housing 12, again
as best seen in FIG. 2.
[0021] The tread brake cylinder 10, illustrated in FIGS. 1 and 2,
operates in the following manner. When a pressurized fluid is
directed to piston 14 through a port 32 provided in housing 12
(FIG. 1), the piston 14 and its wedge 16 are moved toward and into
a position between bearings 22 and 24 such that the legs 18 of the
wedge 16 engage the bearings 22 and 24 in a manner that translates
the bearings 22 and bosses 28 to the left, in FIGS. 1 and 2, as the
rear edge 23 of the wedge 16 engages the bearings 24 rotatably
mounted on fixed bosses 30. The translation of such bearings 22 and
bosses 28 translates the drive sleeve 26 and the push rod 20 to the
left against a horizontal spring 34 located around the push rod 20
and between the drive sleeve 26 and an end wall 36 of housing
12.
[0022] The push rod 20 is mechanically connected to a brake shoe
(not shown) that is disposed to engage the rim of a railway vehicle
wheel (not shown) when the push rod 20 is moved forwardly against
the horizontal spring 34.
[0023] When fluid pressure is removed from the port 32 a vertically
disposed spring 37 located between the piston 14 and the drive
sleeve 26 returns the piston 14 to the upper portion of housing 12
and removes the legs 18 of the wedge 16 from between the roller
bearings 22 and 24. A shallow boss 38 is provided on the drive
sleeve 26 and extends into one end of such spring 37, as seen in
FIG. 1. The lower turns of such vertical spring 37 travel with the
drive sleeve 26 and allow such horizontal spring 34 to return such
push rod 20 and drive sleeve 26 to a position where the brake shoe
clears the rim of the vehicle wheel.
[0024] FIG. 3 of the drawings illustrates a currently available
tread brake unit, generally designated 40, in which an elongated
sleeve 42 extends substantially along the length of such tread
brake unit 40. A pressure ring 44 is located inside of such
elongated sleeve 42 and abuts against a first, relatively short,
horizontal spring 46 located between such pressure ring 44 and a
rear guide bushing 48. A washer 50 is located between such rear
guide bushing 48 and a slack adjuster nut 52 that is threaded onto
threads 55 of a brake applying spindle 1. Slack adjuster nut 52
engages such washer 50 via threads 54 provided on confronting
bevelled surfaces of both the washer 50 and slack adjuster nut
52.
[0025] A leader nut 56 is also threaded onto spindle 1. There is a
second horizontal spring 58 engageable at a rear end thereof with
such leader nut 56. A sleeve 60 is disposed about the second spring
58 and at least a portion of such leader nut 56.
[0026] A rear bearing 62 is disposed between a forward end of such
second spring 58 and a retention ring 64 disposed on such leader
nut 56. Both the spring 58 and the retention ring 64 are located in
sleeve 60.
[0027] A second bearing 66 is located between adjuster nut 52 and a
third horizontal spring 68 captured by a reentrant portion 70 of a
sleeve 72. Bearings 62 and 66 are essentially a ball/thrust type
bearing that can be fully contained assemblies.
[0028] A control socket 74 provides an enclosure for the rear of
such spindle 1 and further provides a certain predetermined travel
distance for the spindle 1. Such travel distance is defined by a
recess 76 provided in such control socket 74 and a rear edge 78 of
the sleeve 60 located in the recess 76. There is also a fourth
spring 34 located between a yoke 27 and a reentrant end wall 36 of
the housing 12.
[0029] The operation of such unit 40 is as follows: air acting on a
piston 14 moves yoke 27 mounted on elongated sleeve 42 to the left,
in FIG. 3, and against the fourth spring 34. Such yoke 27 and
sleeve 42 are translated to the left by the legs (not shown in FIG.
3) of the wedge 16. The sleeve 42 includes a ledge 42a engaging
ring 44 in order to move the ring 44 to the left which, in turn,
moves first spring 46 against bushing 48. Bushing 48, in turn,
urges washer 50 and nut 52 to the left. Such nut 52 moves spindle 1
to the left which, in turn, translates leader nut 56 against second
spring 58 and bearing 62 and, in turn, bearing 62 moves retention
ring 64 to the left.
[0030] Spring sleeve 60 is translated leftwardly with the above
components by elongated sleeve 42 until rear edge 78 of sleeve 60
travels the distance provided by socket recess 76 and engages a
forward socket surface 80. Leftward travel of spring sleeve 60
stops and the brake of the vehicle is now applied. This allows the
beveled teeth on the leader nut 56 to temporarily separate from the
beveled teeth of spring sleeve 60. With nut 56 free of sleeve 60,
spring 58 causes the nut 56 to rotate on threads 55 of spindle 1
with the aid of bearing 62 towards spring sleeve 60 until the
respective beveled teeth of nut 56 and sleeve 60 are
re-engaged.
[0031] When brake air pressure is removed from piston 14, such
fourth spring 34 translates the yoke 27 and sleeve 42 to the right.
Such translation returns the other components to the right until
rear edge 78 contacts the rear of recess 76 of control socket 74.
This stops the retraction of spindle 1 as the sleeve 60 is
re-engaged by nut 56 (which is threaded on the spindle 1).
Elongated sleeve 42 continues rightward movement until it too
reaches the socket 74. This causes the beveled teeth of adjustor
nut 52 to separate from the beveled teeth of the washer 50 such
that nut 52 rotates along the threaded spindle 1 under the force of
spring 68 facilitated by the bearing 66 until such sleeve 42 is
fully returned and nut 52 re-engages with the washer 50.
[0032] As can be appreciated by the drawing of FIG. 3, the brake
unit 40 depicted therein is rather complicated and employs a
substantial number of components to effect an application and
release of railway car brakes. The nuts 52 and 56 are rotatable on
the threaded spindle 1 with the aid of bearings 62 and 66,
respectively, in cooperation with rings 44 and 64. The sleeves 42
and 60 and such springs 46, 58 and 68 function as ratchets and
clutches that make assembly and maintenance of the brake unit 40
costly, heavy and complicated.
[0033] The above described operations are those of a typical tread
type brake unit having components that the present invention
eliminates. The present invention accomplishes this by replacing
such components with a collet style slack adjuster, generally of
the type shown and described in the above shown and incorporated
U.S. Pat. 5,423,401 to Noah et al., and the power collet also shown
in Noah et al. These type collets are generally shown in FIG. 4 of
the present drawings.
[0034] More particularly, FIG. 4 illustrates a tread brake unit or
actuator 90 having a power collet 92 located on a push rod 20. (In
FIG. 4, components that are substantially common with those that
are depicted in FIGS. 1, 2 and 3 have the same reference numerals).
Further, the push rod 20 is preferably provided with external
threads or serrations and the main body portion of the power collet
92 is similarly provided with internal threads or serrations. Such
threads or serrations enhance friction between the push rod 20 and
the power collet 92 when needed.
[0035] Power collet 92 has integral, elongated fingers 94 extending
rearwardly of the main body thereof. These fingers 94, preferably,
have internally smooth surfaces and are thus not provided with
threads or serrations.
[0036] A slack adjusting collet 96 is disposed on push rod 20 at a
location in front of the power collet 92. Such slack adjusting
collet 96 also having an integral, internally smooth, unthreaded
fingers 98 (facing forwardly) and an internally threaded or
serrated surface in the area of the main body thereof.
[0037] Power collet 92 is substantially contained in an elongated
housing 100 disposed about the power collet 92 and push rod 20. The
housing 100 engages the power collet 92 adjacent one end thereof
and supports the fingers 94 adjacent the second end thereof. The
forwardmost ends of the power collet 92 and the housing 100 have,
respectively, corresponding tapered bearing surfaces 102 and 104
for purposes explained hereinafter.
[0038] The slack adjusting collet 96 is contained within a fixed
housing 106 which is also disposed about the push rod 20. This
housing 106 has forward and rear surfaces 108 and 110,
respectively, which the slack adjusting collet 96 abuts in manners
described hereinafter.
[0039] A rear cover 112 is located and suitably secured to the
housing 12 of such brake unit 90. Cover 112 protects the rear of
such push rod 20 and is sized to provide a positive stop for
rearward travel of the power collet 92 for reasons explained
below.
[0040] Brake unit 90 further includes a yoke 27 supporting axially
translatable roller bearings 22 located on opposed sides of the
yoke 27, while roller bearings 24 are similarly located on opposite
sides of the housing 12. The yoke 27 is mounted on and engages the
housing 100 of such power collet 92.
[0041] Like the units of FIGS. 1 to 3, brake unit 90 includes a
piston 14 and wedge 16 that are moved downwardly (in FIG. 4) when a
pressurized fluid is supplied to a housing port 32 above the piston
14. When the wedge fingers (not visible in FIG. 4) enter between
the bearings 22 and 24, such yoke 27 is translated to the left in
FIG. 4 and, in turn, forwardly translates the collet housing 100 to
the left in FIG. 4. When housing 100 moves forwardly, its tapered
bearing surface 104 engages the bearing surface 102 of the power
collet 92 to force the collet 92 into clamping engagement with the
push rod 20. Forward movement of the yoke 27 and collet housing 100
now translates the push rod 20 to move a brake shoe (not shown) to
engage an associated wheel of the vehicle (not shown).
[0042] Movement of the push rod 20 also translates slack adjusting
collet 96 forwardly until the brake shoe engages the vehicle wheel
or until the forward face of the collet 96 abuts surface 108 of
housing 106. This occurs if the brake shoe and/or wheel is worn to
the extent that the collet 96 travels to housing surface 108, i.e.,
when brake unit 90 is deenergized, a clearance or space "A" (see
FIG. 4) exists between the collet 96 and the housing surface 108
that corresponds to a typical clearance (not shown) between the
brake shoe and the wheel. This clearance allows the wheel to rotate
free of the brake shoe when the brakes of a train vehicle are not
applied.
[0043] When collet 96 abuts housing surface 108, its fingers 98
flex radially outwardly as the teeth of the collet 96 ride over the
teeth on push rod 20. This overcomes the friction between the push
rod 20 and collet 96 provided by the force of wedge 16 acting on
and between roller bearings 22 and 24. The push rod 20 now travels
through the collet 96 until the brake shoe engages and applies a
braking force to the vehicle wheel.
[0044] The braking force remains until the pressure is removed from
the port 32 and piston 14 in housing 12. When such pressure is
removed, the piston 14 returns to a non-braking position in such
housing 12 under urging of vertical spring 37 and the integral
wedge fingers 18 (FIG. 2) are withdrawn from between bearings 22
and 24.
[0045] With the withdrawal of the wedge fingers 18 the horizontal
spring 34, acting upon yoke 27, returns the push rod 20 and slack
adjusting and power collets 96 and 92, respectively, toward the
rear of housing 12 (and to the right in FIG. 4). The slack
adjusting collet 96 travels rearwardly until it abuts surface 110
of its fixed housing 106 and its fingers 98 move inwardly to fully
engage the push rod 20. This stops movement of the push rod 20 and
the actuator 90 of the present invention is now adjusted to any new
clearance "A" caused by wear of the wheel tread and brake shoe
material, i.e., when the brake shoe is again applied to the wheel
the push rod 20 and slack adjusting collet 96 will travel distance
"A" to fully apply the brake shoe to the wheel without push rod 20
moving through collet 96.
[0046] Yoke 27, in translating power collet 92 to the rear in
actuator housing 12, also translates housing 100 of the power
collet to the rear. This is effected by housing 100 engaging a
ledge 114 of the power collet to move the power collet to the rear.
As seen in FIG. 4, yoke 27 is held in place on housing 100 by a
retention ring 116 seated in an appropriate slot 118 provided in
the outside surface of power collet housing 100.
[0047] With rearward movement of housing 100, bearing surface 104
thereof moves away from the bearing surface 102 of the collet 92,
which allows its fingers 94 to flex outwardly from push rod 20 (by
virtue of the threads of the collet riding over the threads of the
push rod) to release the power collet from the push rod. The power
collet 92 is now free to slide over the push rod 20 if the yoke 27
and power collet housing 100 are not in a fully retracted
position.
[0048] When changing brake shoes, actuator 90 is reset manually by
push rod 20 into housing 12 until power collet fingers 94 contact
rear cover 112 of the actuator 90. When this happens, the power
collet 92 is no longer able to move its bearing surface 102 into
engagement with the bearing surface 104 of housing 100. This
prevents the power collet from clamping on the push rod.
[0049] The tread brake actuator 90 of the present invention is
substantially simple in construction as it involves only five basic
components in the form of two threaded collets 92 and 96, two
housings 100 and 106 and a push rod 20. Such components, in
addition, are relatively easy to make, generally maintenance free
and require an assembly time involving only the placing of the
collets and housings on a push rod. Hence, no special equipment is
needed to install the housings and collets of the invention. The
mechanisms of the invention are also light in weight, as the
collets and housings are low mass items. They can also be used to
convert most tread brake actuators, as the collets and housings are
simply disposed on a push rod in a manner providing an appropriate
brake shoe clearance "A".
[0050] While a presently preferred embodiment for carrying out the
instant invention has been set forth in detail above, those persons
skilled in the tread brake art to which this invention pertains
will recognize various alternative ways of practicing the invention
without departing from the spirit and scope of the claims appended
hereto.
* * * * *