US20170008539A1

US20170008539A1 - Slack adjuster for railcar brake

Info

Publication number: US20170008539A1
Application number: US14/793,768
Authority: US
Inventors: Michael E. Ring
Original assignee: Amsted Rail Co Inc; Amsted Rail Faiveley LLC
Current assignee: Amsted Rail Co Inc
Priority date: 2015-07-08
Filing date: 2015-07-08
Publication date: 2017-01-12
Also published as: WO2017007652A1

Abstract

A slack adjuster for railroad car braking system is provided. The slack adjuster includes a first jaw positioned at a first end of the slack adjuster and a second jaw positioned at a second end of the slack adjuster. A rod assembly is attached to the first jaw and a tube is attached to the second jaw. A nut assembly is provided for transferring a force between the rod assembly and the tube. One or more components configured to bear an axial load of the slack adjuster are attached to the tube by crimping at least a portion of the tube into a groove defined in an outer surface of such component.

Description

FIELD OF THE INVENTION

The present invention generally relates to a slack adjuster for a railway car braking system.

BACKGROUND OF THE INVENTION

Railway cars are widely used for transportation of goods and passengers throughout the United States and abroad. Railway cars generally include one or more truck assemblies including a plurality of specially designed wheels for traveling along a vast infrastructure of railway car tracks. Braking systems are generally disposed between adjacent pairs of wheels for facilitating the stopping or slowing down of the railway car.
A braking system can generally include a pair of brake assemblies corresponding to a pair of trucks supporting a railway car. Each of the brake assemblies includes leading and trailing brake beam assemblies, each with a pair of brake heads having brake shoes for contact with an outer periphery of the wheels when the leading and trailing brake beam assemblies are moved away from one another. Commonly, an air cylinder is provided between the pair of brake assemblies in the braking system for generating the force that causes such movement. The air cylinder or another actuator is connected to each of the pair of brake assemblies and respective leading and trailing brake beam assemblies through a linkage system including various rods and levers.
Many braking systems further include assemblies conventionally known as slack adjusters for adjusting the movement of the leading and trailing brake beam assemblies of the respective brake assemblies as required. In particular, slack adjusters compensate for brake shoe wear and wheel wear by adjusting its length. Typically, a slack adjuster is built into one of the rods in linkage system.
Accordingly, the slack adjuster must be capable of withstanding a large amount of force. For example, certain slack adjusters must be capable of withstanding more than of 20,000 to 30,000 pounds of force during operation. In order to accommodate such a large amount of force, the load bearing components of the slack adjuster are typically connected using intricate bolting systems. With such systems, however, the parts must be thicker than may otherwise be necessary to accommodate the holes for the bolts, and each of the holes must he precisely cut.
Therefore, an improved system or method for attaching components of a slack adjuster capable of bearing a large amount of force would be useful.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may he learned through practice of the invention.
In one exemplary embodiment of the present invention, a slack adjuster is provided for a railroad car braking system. The slack adjuster defines an axial direction and a circumferential direction. The slack adjuster includes a first jaw, a rod assembly attached to the first jaw, a nut assembly having at least a portion rotatably engaged with the rod assembly, and a tube attached to the nut assembly. The tube extends generally along the axial direction between a first end and a second end. Additionally, the tube encloses at least a portion of the rod assembly. The slack adjuster additionally includes a second jaw including a base attached to the second end of the tube. The base of the second jaw defines a groove therein extending generally along the circumferential direction, at least a portion of the tube crimped into the groove in the base of the second jaw attaching the tube to the base of the second jaw.
In another exemplary embodiment of the present invention, a slack adjuster is provided for a railroad car braking system defining an axial direction and a circumferential direction. The slack adjuster includes a first jaw and a second jaw. The first jaw is positioned at a first end of the slack adjuster along the axial direction and the second jaw is positioned at a second end of the slack adjuster along the axial direction. The slack adjuster additionally includes a rod assembly attached to the first jaw and extending generally along the axial direction, a tube attached to the second jaw and also extending generally along the axial direction, and a nut assembly configured to transfer a force between the rod assembly and the tube. The nut assembly includes a first bearing collar defining a groove therein extending generally along the circumferential direction. At least a portion of the tube is crimped into the groove in the first bearing collar, attaching the tube to the first bearing collar.
In an exemplary aspect of the present disclosure, a method for manufacturing a slack adjuster for a railroad car braking system is provided. The slack adjuster defines an axial direction and the method includes attaching a first jaw to a rod assembly, positioning a nut assembly over a threaded portion of the rod assembly, and attaching the nut assembly to a tube extending generally along the axial direction such that at least a portion of the nut assembly is fixed along the axial direction relative to the tube. The method also includes attaching the tube to a base of a second jaw by crimping a portion of the tube into a groove defined in the base of the second jaw, fixing the base of the second jaw to the tube.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 provides a braking system in accordance with an exemplary embodiment of the present disclosure installed in an exemplary railway car truck.

FIG. 2 provides a perspective view of a slack adjuster in accordance with an exemplary embodiment of the present disclosure.

FIG. 3 provides a close up exploded view of a portion of the exemplary slack adjuster of FIG. 2, prior to installation of a pawl box.

FIG. 4 provides a close-up perspective view of a portion of the exemplary slack adjuster of FIG. 2, with the pawl box installed.

FIG. 5 provides a side, cross-sectional view of a center portion of the exemplary slack adjuster of FIG. 2.

FIG. 6 provides a perspective view of a first bearing collar of a nut assembly of the exemplary slack adjuster FIG. 2.

FIG. 7 provides a perspective view of a second bearing collar of the nut assembly of the exemplary slack adjuster of FIG. 2

FIG. 8 provides a perspective view of a second end of the exemplary slack adjuster of FIG. 2.

FIG. 9 provides a side, cross-sectional view of the second end of the exemplary slack adjuster of FIG. 2.

FIG. 10 provides a side, cross-sectional view of a crimp die for crimping a portion of the tube of the exemplary slack adjuster of FIG. 2 into a groove defined in a component of the exemplary slack adjuster of FIG. 2.

FIG. 11 provides a flow diagram of a method for manufacturing a slack adjuster in accordance with an exemplary aspect of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Referring now to the Figures, FIG. 1 provides a braking system 50 in accordance with an exemplary embodiment of the present disclosure. The braking system 50 is generally referred to as a body mounted brake system, configured for attachment to a body of a railway car (not shown). It should be appreciated, however, that in other exemplary embodiments, the braking system 50 may instead he what is generally referred to as a truck mounted brake system mounted to a railway car truck.
As shown, the braking system 50 generally includes a leading braking system 52 and a trailing braking system 54 spaced from one another along a longitudinal direction L. The leading braking system 52 may be configured with a leading railway car truck having a plurality of wheels and mounted under the railway car (not shown), and similarly the trailing braking system 54 may be configured with a trailing railway car truck having a plurality of wheels and also mounted under the railway car (not shown). The wheels of the leading and trailing railway car trucks may be configured to engage an infrastructure of railway car tracks. As used herein, the terms “leading” and “trailing” are terms used to describe a location of certain components relative to other components, it being understood that in other embodiments, the orientation of such components may be reversed.
The leading and trailing braking system 52, 54 each include a leading brake beam assembly 56 and a trailing brake beam assembly 58. Each of the leading and trailing brake beam assemblies 56, 58 on the leading and trailing braking assemblies 52, 54 include a pair of brake heads 60 disposed at their respective outer ends. The brake heads 60 each include one or more brake shoes 62 defining a thickness and configured to contact an outer periphery of respective wheels of the railway car trucks.
The braking system 50 is configured to generate friction with the wheels of the respective railway car trucks to slow the railway car. For the embodiment depicted, the leading and trailing brake beam assemblies 56, 58 of the leading and trailing brake assemblies 52, 54 are moved away from one another along the longitudinal direction L in order to generate the desired friction between brake shoes 62 and the respective wheels. More particularly, the braking system 50 generally includes a brake cylinder 64 configured to move the respective leading and trailing brake beam assemblies 56, 58 away from one another along the longitudinal direction L by transferring a force through a lever assembly 66. The lever assembly 66 generally includes a plurality of levers 68 and fixed length rods 70 to generate the desired movement of the respective brake beam assemblies 56, 58 from the brake cylinder 64. However, as the brake shoes 62 on the brake beam assemblies 56, 58 and the wheels of the various trucks wear down through use of the braking system 50, a thickness of the respective brake shoes 62 and a diameter of the respective wheels may be reduced. In order to accommodate these reductions, a slack adjuster 72 is provided. The slack adjuster 72 is configured to shorten in length in order to compensate for the reduced thickness of the brake shoes 62 and/or diameter of the wheels.
One having skill in the art will appreciate, however, that in other exemplary embodiments, the braking system 50 may have any other suitable configuration of leading or trailing brake assemblies 52, 54, including the respective leading and trailing brake beam assemblies 56, 58. Additionally, in other exemplary embodiments, brake system 50 may utilize any other suitable means for generating a braking force other than the brake cylinder 64, and additionally, or alternatively, may utilize any other suitable configuration of lever assembly 66 to transfer such braking force to the leading and trailing brake assemblies 52, 54. Moreover, in still other exemplary embodiments, the slack adjuster 72 may be positioned elsewhere in the braking system 50, or may be configured in any other suitable manner to compensate for the reduction in the thickness of the brake shoes 62 and/or the diameter of the various wheels.
Referring now to FIG. 2, a slack adjuster 100 in accordance with an exemplary embodiment of the present disclosure is depicted. The exemplary slack adjuster 100 depicted in FIG. 2 may be configured in substantially the same manner as the slack adjuster 72 described above with reference to FIG.1, and accordingly may be utilized in a braking system such as the exemplary braking system 50 also described above with reference to FIG. 1.
The slack adjuster 100 depicted defines an axial direction A, a radial direction R, and a circumferential direction C, and extends generally along the axial direction A between a first end 102 and a second end 104. The slack adjuster 100 includes a first jaw 106 positioned at the first end 102 and a second jaw 108 positioned at the second end 104. A rod assembly 110 is attached to the first jaw 106 and extends generally along the axial direction A. Additionally, a tube 112 is attached to the second jaw 108 and also extends generally along the axial direction A. The tube 112 encloses at least a portion of the rod assembly 110. As will be discussed in greater detail below, a nut assembly 114 (see FIG. 5) having at least a portion rotatably engaged with the rod assembly 110 is configured to transfer a force between the rod assembly 110 and the tube 112 and is also configured to allow the rod assembly 110 to extend or retract relative to the tube 112.
Referring now also to FIGS. 3 and 4, the slack adjuster 100 additionally includes a pawl box 116 attached to an outer surface 118 of the tube 112 over a pair of pawl openings 120 in the tube 112. More particularly, FIG. 3 provides a close-up perspective view of the slack adjuster 100 of FIG. 2 prior to attachment of the pawl box 116, and FIG. 4 provides a close-up perspective view of the slack adjuster 100 of FIG. 2 after attachment of the pawl box 116.
As may be clearly seen in FIG. 3, the tube 112 defines a pair of pawl openings 120 and at least one locator opening 122 positioned adjacent to the pawl openings 120. More particularly, for the embodiment depicted, the tube 112 defines two locator openings 122. The pawl openings 120 are positioned adjacent to the nut assembly 114 of the slack adjuster 100 (see FIG. 5, below) and are each configured to receive a pawl that restricts or allows rotational movement of at least a portion of the nut assembly 114 relative to the tube 112. Moreover, the pawl box 116 includes a main slot 124 configured to hold the one or more pawls in the pawl openings 120 of the tube 112 when attached to the tube 112. The pawl box 116 additionally includes a trigger slot 126. The trigger slot 126 is configured to receive a trigger that selectively engages or disengages one or both of the pawls to allow the slack adjuster 100 to extend or retract as necessary.
Moreover, the pawl box 116 additionally includes at least one locator tab 128 and at least two coupling projections 130. More particularly, for the embodiment depicted, the pawl box 116 include two locator tabs 128. When the pawl box 116 is attached to the tube 112, the locator tabs 128 of the pawl box 116 extend into the locator openings 122 in the tube 112. It should be appreciated, however, that in other exemplary embodiments, the tube 112 may define any other suitable number of locator openings 122, and similarly the pawl box 116 may include any other suitable number of locator tabs 128. Additionally, or alternatively, the tube 112 may not define any locator openings 122, and instead the at least one locator tab 128 may be configured to extend into one or more of the pawl openings 120.
Moreover, referring particularly to FIG. 4, for the embodiment depicted, the pawl box 116 is attached to the tube 112 by forming the at least two coupling projections 130 of the pawl box 116 around the outer surface 118 of the tube 112. For example, the pawl box 116 may be attached to the tube 112 by placing the tube 112 in a circular die, and pressing the pawl box 116 onto the tube 112 such that the coupling projections 130 are pressed/deformed by the circular die around the outer surface 118 of the tube 112 to hold the pawl box 116 in place. Such a configuration may allow for a slack adjuster 100 capable of more easily being assembled or manufactured. More particularly, with such a configuration the pawl box 116 need not be welded to the outer surface of the tube 112 of the slack adjuster 100,
Referring still to FIG. 4, and now also to FIG. 5, the nut assembly 114 of the exemplary slack adjuster 100 of FIG. 2 will now he described. As stated, FIG. 4 provides a close-up perspective view of a center portion of the slack adjuster 100 of FIG. 2. Additionally, FIG. 5 provides a side, cross-sectional view of the center portion of the slack adjuster 100 of FIG. 2.
As may be more clearly seen in FIG. 5, the nut assembly 114 generally includes a nut 132 defining a threaded opening 134 rotatably engaged with a threaded portion 136 of the rod assembly 110. More particularly, for the embodiment depicted, the nut 132 is threaded onto (or screwed onto) the threaded portion 136 of the rod assembly 110. As will be understood, the nut 132 also includes a geared outer surface 138 configured to be engaged by the pair of pawls received in the pair of pawl openings 120 of the tube 112. The not assembly 114 additionally includes a first bearing collar 140 and a second bearing collar 142. The first bearing collar 140 is sometimes referred to as a cone collar, and the second bearing collar 142 is sometimes referred to simply as a bearing collar. The first and second bearing collars 140, 142 are disposed on opposite sides of the nut 132 along the axial direction A for constraining the nut 132 along the axial direction A of the slack adjuster 100 relative to the tube 112.
A pair spring washers 144 are provided between the nut 132 and the first bearing collar 140 to bias the nut 132 away from the first bearing collar 140 along the axial direction A. For the embodiment depicted, the nut 132 includes a bearing 146 between the nut 132 and spring washers 144 to allow for the nut 132 to more easily rotate relative to the spring washers 144 and first bearing collar 140. Additionally, the first bearing collar 140 includes a tapered cone surface 148 corresponding in shape with a tapered surface defined at an axial end 150 of the nut 132. When the nut 132 is pressed against the tapered cone surface 148 of the first bearing collar 140 (after having overcome the bias of the spring washers 144), the nut 132 may be fixed rotationally to the first hearing collar 140. A bearing 152 is also provided between the second bearing collar 142 at an opposite axial end 154 of the nut 132 to allow the nut 132 to more easily rotate relative to the second bearing collar 142.
The first and second bearing collars 140, 142 are each rigidly attached to the tube 112. During operation of the slack adjuster 100, an axial force may be applied between the first and second jaws 106, 108 of the slack adjuster 100. The nut assembly 114 is configured to transfer such a force between the rod assembly 110 (which receives the force from and/or transfers the force to the first jaw 106) and the tube 112 assembly (which receives the force from and/or transfers the force to the second jaw 108). More particularly, for the exemplary slack adjuster 100 depicted, the first bearing collar 140 is configured to transfer such force between the rod assembly 110 and the tube 112. However, in other embodiments, the second bearing collar 142 may additionally, or alternatively, be configured to transfer such force. Accordingly, the attachment between first and/or second bearing collars 140, 142 and the tube 112 must be capable of withstanding a potentially large amount of force applied between the first and second jaws 106, 108 of the slack adjuster 100 along the axial direction A.
The inventors in the present application have found that contrary to conventional wisdom, the nut assembly 114 may be attached to the tube 112 by crimping, while still being capable of withstanding the potentially large amount of force along the axial direction A. Such an attachment method, the inventors found is enabled at least in part due to the selection of materials and design of the components, as discussed below.
For example, referring now also to FIG. 6, depicting a close-up, perspective view of the first bearing collar 140 of the nut assembly 114, the first bearing collar 140 defines a groove 156 in an outer surface 158 extending generally along the circumferential direction C. At least a portion of the tube 112 is crimped into the groove 156 of the first hearing collar 140, rigidly attaching the tube 112 to the first bearing collar 140. Moreover, the first bearing collar 140 defines a center opening 160 through which a portion the rod assembly 110 extends (FIG. 5). The exemplary first bearing collar 140 depicted is a solid component between the center opening 160 and the groove 156 free from any openings or holes.
Additionally, for the embodiment depicted, the first bearing collar 140 of the nut assembly 114 may be formed of a steel material having a tensile strength of at least about seventy-five (75) kilopounds per square inch (“ksi”) and a yield strength of at least about sixty (60) ksi. More particularly, the first bearing collar 140 may have a tensile strength of at least about eighty (80) ksi and a yield strength of at least about sixty-five (65) ksi, or may have a tensile strength of at least about eighty-five (85) ksi and a yield strength of at least about seventy (70) ksi. For example, the first hearing collar 140 may he formed of a Chinese No. 45 steel. Moreover, the tube 112 may also be formed of a steel material having a tensile strength of at least about seventy (70) ksi and a yield strength of at least about sixty (60) ksi. More particularly, the tube 112 may have a tensile strength of at least about seventy-five (75) ksi and a yield strength of at least about sixty-five (65) ksi, or may have a tensile strength of at least about eighty (80) ksi and a yield strength of at least about seventy (70) ksi. For example, the tube 112 may be formed of a 1026 carbon steel, conforming to the American Society for Testing and Materials (“ASTM”) A513 Type 5 Drawn Over Mandrel.
It should be appreciated, that as used herein, terms of approximation, such as “about” or “approximately,” refer to being within a ten percent (10%) margin of error.
Notably, prior configurations have attached the first bearing collar 140 to the tube 112 by having a plurality of holes extending along the radial direction R between the center opening 160 and the outer surface 158 of the first bearing collar 140 corresponding to similar openings in the tube 112. The holes in the first bearing collar 140 in prior configurations were threaded such that bolts may be used to attach the first bearing collar 140 to the tube 112. Such a configuration required each hole to he precisely drilled and tapped. Additionally, such a configuration required an increased thickness of the tube 112 and first bearing collar 140 such that the tube 112 and first bearing collar 140 could withstand the necessary forces along the axial direction A despite the holes drilled therethrough. By contrast, however, with the present configuration no such holes need to be drilled and/or threaded in order to attach the tube 112 and first bearing collar 140. Accordingly, the present configuration may provide for a much more efficient and less time-consuming process for manufacturing and attaching the first bearing collar 140 to the tube 112. Additionally, the tube 112 may define a lesser thickness, such that a weight of the tube 112 and slack adjuster 100 are decreased with the present configuration.
Similarly, referring still to FIG. 5 and now also to FIG. 7, depicting a close-up, perspective view of the second bearing collar 142 of the nut assembly 114, the second bearing collar 142 also defines a groove 162 in an outer surface 164 extending generally along the circumferential direction C. At least a portion of the tube 112 is crimped into the groove 162 and the second bearing collar 142, attaching the tube 112 to the second bearing collar 142. The second bearing collar 142 also defines a center opening 166 through which a portion of the rod assembly 110 extends. The second bearing collar 142 is also a solid component between the center opening 166 and the groove 162 defined in its outer surface 164, free from any openings or holes, and may be formed of the same material as the first bearing collar 140 discussed above. Accordingly, the present configuration may also provide for a much more efficient and less time-consuming process for attaching the second bearing collar 142 to the tube 112 and for manufacturing the slack adjuster 100, as well as the other benefits discussed above.
Referring now to FIGS. 8 and 9, a perspective view and side cross-sectional view of the second end 104 of the slack adjuster 100 are provided. Similar to the first and second bearing collars 140, 142, the second jaw 108 of the exemplary slack adjuster 100 depicted is attached to the tube 112 by crimping. More particularly, the second jaw 108 includes a substantially smooth cylindrical base 168 defining a groove 170 in an outer surface 172 extending generally along the circumferential direction C. At least a portion of the tube 112 is crimped into the groove 170 in the base 168 of the second jaw 108, attaching the tube 112 to the base 168 of the second jaw 108. For the exemplary embodiment depicted, the groove 170 in the base 168 of the second jaw 108 also defines a width W_Galong the axial direction A and a depth D_Galong the radial direction R. In certain exemplary embodiments, the width W_Gof the groove 170 in the base 168 the second jaw 108 may be at least about 0.40 inches wide, at least about 0.50 inches wide, or at least about 0.75 inches wide. Additionally, in certain exemplary embodiments, the depth D_Gof the groove 170 in the base 168 of the second jaw 108 may be at least about 0.10 inches deep, at least about 0.15 inches deep, or at least about 0.20 inches deep.
Moreover, as shown most clearly in FIG. 9, the second jaw 108 includes a flange 174 having a width W_Falong the axial direction A. For the embodiment depicted, the flange 174 has a width W_Falong the axial direction A of at least about 0.15 inches. Additionally, the second jaw 108 may be formed of a steel material having a tensile strength of at least about eighty (80) ksi and a yield strength of at least about seventy (70) ksi. More particularly, the second jaw 108 may have a tensile strength of at least eighty-five (85) ksi and a yield strength of at least about sixty-five (75) ksi, or may have a tensile strength of at least about ninety (90) ksi and a yield strength of at least about eighty (80) ksi. For example, the second jaw 108 may be formed of 1035 steel.
It should be appreciated, however, that the dimensions provided above are by way of example only, and that in other exemplary embodiments, the flange 174 may have any other suitable width W_F, the groove 170 in the base 168 of the second jaw 108 may have any other suitable width W_G, and the groove 170 in the base 168 of the second jaw 108 may also have any other suitable depth D_G. For example, in other exemplary embodiments, the flange 174 may be at least about 0.20 inches wide, at least about 0.25 inches wide, or at least about 0.30 inches wide. Additionally, or alternatively, in other exemplary embodiments, the groove 170 in the base 168 may be an overly wide groove, defining a width W_Ggreater than or equal to about three inches, greater than or equal to about five inches, or greater than or equal to about seven inches. Further, in still other exemplary embodiments, the groove 170 in the base 168 may actually be a plurality of circumferential grooves spaced along the base 168 of the second jaw 108. Such a configuration may provide additional strength to the connection between the second jaw 108 and the tube 112.
Notably, the inventors have unexpectedly found that the slack adjuster 100 can withstand a relatively large force along the axial direction A with the first bearing collar 140 and the second jaw 108 attached to the tube 112 by crimping. More particularly, the inventors have unexpectedly found that a slack adjuster 100 in accordance with the following exemplary embodiment can withstand a relatively large force along the axial direction A with the first bearing collar 140 and the second jaw 108 attached to the tube 112 by crimping: (a) when the tube 112 is formed of a material having a tensile strength of at least about eighty (80) ksi and a yield strength of at least about seventy (70) ksi; (b) when the first bearing collar 140 is formed of a material having a tensile strength of at least about eighty-five (85) ksi and a yield strength of at least about seventy (70) ksi; (c) when the second jaw 108 is formed of a material having a tensile strength of at least about ninety (90) ksi and a yield strength of at least about eighty (80) ksi; (d) when the second jaw 108 includes a flange 174 having a width W_Falong the axial direction of at least about 0.15 inches; and (e) when the second jaw 108 defines a groove 170 in the base 168 having a width W_Gof at least about 0.50 inches and a depth D_Gof at least about 0.15 inches. With such an exemplary embodiment, the inventors have unexpectedly found that the exemplary slack adjuster 100 may be capable of withstanding at least about 60,000 pounds of force along the axial direction A. Such a configuration may therefore withstand the typical forces incurred during operation of a braking system, plus an additional safety factor.
Referring particularly to FIG. 9, the base 168 of the second jaw 108 defines a central opening 176 extending generally along the axial direction A through at least a portion of the base 168 of the second jaw 108. The base 168 of the second jaw 108 is a solid component between the central opening 176 and the groove 170, free from any openings or holes. It should be appreciated, however, that in other exemplary embodiments, the base 168 may not include an opening 176. Accordingly, the present configuration may also provide for a much more efficient and less time-consuming process for attaching the base 168 of the second jaw 108 to the tube 112 and for manufacturing the slack adjuster 100, as well as the other benefits discussed above.
Referring now to FIG. 10, a close-up view is provided of a groove 178 defined in an outer surface 180 of a component 182 and a crimp die 184. The crimp die 184 is configured to move generally along the radial direction R and press/deform a portion of the tube 112 (original shape of tube 112 shown as numeral 112′ in phantom) into the groove 178 defined in the outer surface 180 of the component 182. The crimp die 184 defines a width W_CDalong the axial direction A. The width W_CDof the crimp die 184 is chosen such that once the portion of the tube 112 is pressed/deformed into the groove 178 defined in the outer surface 180 the component 182, such portion of the tube 112 conforms to the shape of the groove 178. For example, the width W_CDof the crimp die 184 may be approximately equal to a width W_G, of the groove 178 minus twice a thickness T_Tof the tube 112. Such a configuration may provide an attachment point capable of withstanding the axial forces required by the slack adjuster 100.
The exemplary groove depicted defines a pair of inner edges 186 and a pair of top ledges 188 (along the axial direction A). Additionally, the crimp die 184 defines a crimping portion 190 defining a pair of crimping edges 192. For the exemplary embodiment depicted, each of the inner edges 186, the top ledges 188, and the crimping edges 192 define a radius, or a radius of curvature R_C, greater than zero. More particularly, for the embodiment depicted, each of the inner edges 186, the top ledges 188, and the crimping edges 192 define a radius R_Cgreater than or equal to about ⅛th of an inch (0.125 inches). However, in other exemplary embodiments, one or more of the inner edges 186, the top ledges 188, and the crimping edges 192 may define a radius R_Cgreater than or equal to about 1/10th of an inch (0.10 inches), greater than or equal to about ⅙th of an inch (0.16 inches), or greater than or equal to about ¼th of an inch (0.25 inches). Moreover, it should be appreciated, that in still other exemplary embodiments, one or more of the inner edges 186, the top ledges 188, and the crimping edges 192 may define any other suitable radius R_C, or may define a radius R_Cequal to zero (i.e., a ninety degree edge). As used herein, the term “radius” or “radius of curvature” and is the radius of the circle that touches a curve at a given point and has the same tangent and curvature at that point.
Furthermore, it should be appreciated, that the exemplary groove 178 defined in the outer surface 180 of the component 182 depicted in FIG. 10 may represent one or more of the groove 156 defined in the outer surface 158 of the first bearing collar 140, the groove 162 defined in the outer surface 164 of the second bearing collar 142, and/or the groove 170 defined in the outer surface 172 of the base 168 of the second jaw 108. Further, in certain exemplary embodiments, one or more other portions of the exemplary slack adjuster 100 may be attached using a similar crimping method. For example, referring back briefly to FIG. 2, the exemplary slack adjuster 100 additionally includes an end cap 194 defining a groove 196 extending generally along the circumferential direction C in an outer surface with at least a portion of the tube 112 crimped therein, attaching the tube 112 to the end cap 194. As will be appreciated, at least a portion of the rod assembly 110 slidably extends through an opening in the end cap 194 (not shown), and the end cap 194 does not support an axial force applied between the first and second jaws 106, 108.
Referring now to FIG. 11, a flow diagram is provided of an exemplary method (200) for manufacturing a slack adjuster for railroad car braking system in accordance with an exemplary aspect of the present disclosure. In certain exemplary aspects, the exemplary method (200) may be used to manufacture the exemplary slack adjuster depicted in FIG. 2 and described above.
As indicated, the exemplary method (200) generally includes at (202) attaching a first jaw to a rod assembly and at (204) positioning a nut assembly over a threaded portion of the rod assembly. Moreover, the exemplary method (200) includes at (206) attaching the nut assembly to a tube extending generally along the axial direction, such that at least a portion of the nut assembly is fixed along the axial direction relative to the tube. Although not depicted, in certain exemplary aspects, attaching the nut assembly to the tube at (206) may include crimping a portion of the tube into a groove defined in an outer surface of a first bearing collar and/or crimping a portion of the tube into a groove defined in an outer surface of a second bearing collar.
Referring still to FIG. 11, the exemplary method (200) includes at (208) attaching the tube to a base of a second jaw by crimping a portion of the tube into a groove defined in the base of the second jaw, fixing the base of the second jaw to the tube. In certain exemplary aspects, attaching the tube to a base of the second jaw by crimping a portion of the tube into the groove defined in the base of the second jaw at (208) includes crimping a portion of the tube into the groove defined in the base of the second jaw using a plurality of crimp dies. Each of the plurality of crimp dies includes a crimping portion, and in certain exemplary aspects, each of the crimping portions may define a crimping edge having a radius of at least about ⅛th of an inch. However, in other exemplary aspects, the crimping edges of the crimping portions may define any other suitable radius, or no radius at all.
Moreover, for the exemplary method (200) depicted in FIG. 11, the method (200) further includes attaching a pawl box to the tube at (210). Attaching the pawl box to the tube at (210) may include positioning the pawl box over a pair of pawl openings defined in the tube such that at least one locator tab of the pawl box extends into at least one locator opening defined in the tube. Additionally, attaching the pawl box to the tube at (210) may also include forming a pair of coupling projections around an outer surface of the tube.
As is also depicted, for the exemplary method (200) depicted in FIG. 11, the exemplary method (200) also includes reconditioning the slack adjuster at (212). Reconditioning the slack adjuster at (212) may take place, e.g., after extended use of the slack adjuster wherein repairs may be necessary. For example, reconditioning the slack adjuster at (212) may take place after ten years or more of use of the slack adjuster. Alternatively, reconditioning the slack adjuster at (212) may take place during an initial manufacturing of the slack adjuster in order to readjust or correct a mistake made during such manufacturing process. Regardless, reconditioning the slack adjuster at (212) may include removing the second jaw from the tube by shearing off the portion of the tube crimped into the groove in the base of the second jaw with a plurality of crimp dies. Moreover, in other exemplary aspects, reconditioning the slack adjuster at (212) may additionally or alternatively include removing one or more portions of the nut assembly by shearing off the portion of the tube crimped into the groove in the first bearing collar and/or the portion of the tube crimped into the groove in the second bearing collar. The crimp dies used for shearing off such portions of the tube may define a width along the axial direction of the slack adjuster approximately equal to or slightly less than a width of the respective groove. However, in other exemplary aspects, reconditioning the slack adjuster at (212) may alternatively include removing the portion of the tube crimped into the groove in the base of the second jaw and/or a groove in one or more portions of the nut assembly by using a tube cutter, machining such portion off, or using any other suitable method.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. For example, in other embodiments, elements of the exemplary methods described herein may be performed in any suitable order. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

What is claimed is:

1. A slack adjuster for a railroad car braking system defining an axial direction and a circumferential direction, the slack adjuster comprising:

a first jaw;

a rod assembly attached to the first jaw;

a nut assembly having at least a portion rotatably engaged with the rod assembly;

a tube attached to the nut assembly and extending generally along the axial direction between a first end and a second end, the tube enclosing at least a portion of the rod assembly; and

a second jaw including a base attached to the second end of the tube, the base of the second jaw defining a groove therein extending generally along the circumferential direction, at least a portion of the tube crimped into the groove in the base of the second jaw attaching the tube to the base of the second jaw.

2. The slack adjuster of claim 1, wherein the base of the second jaw defines a central opening and is a solid component between the central opening and the groove, free from any opening or holes.

3. The slack adjuster of claim 1, wherein the groove in the base of the second jaw defines an inner edge having a radius greater than or equal to about ⅛th of an inch.

4. The slack adjuster of claim 1, wherein the nut assembly includes a nut defining a threaded opening rotatably engaged with a threaded portion of the rod assembly, a first bearing collar, and a second bearing collar, wherein the first and second bearing collars are disposed on opposite sides of the nut along the axial direction for constraining the nut along the axial direction of the slack adjuster relative to the tube,

5. The slack adjuster of claim 4, wherein the first bearing collar defines a groove in an outer surface extending generally along the circumferential direction, and wherein at least a portion of the tube is crimped into the groove in the first bearing collar attaching the tube to the first bearing collar.

6. The slack adjuster of claim 5, wherein the first bearing collar defines a center opening through which a portion of the rod assembly extends, and wherein the first bearing collar is a solid component between the center opening and the groove, free from any opening or holes.

7. The slack adjuster of claim 5, wherein the groove in the first hearing collar defines an inner edge having a radius greater than or equal to about ⅛th of an inch.

8. The slack adjuster of claim 5, wherein the second bearing collar also defines a groove in an outer surface extending generally along the circumferential direction, and wherein at least a portion of the tube is crimped into the groove in the second bearing collar attaching the tube to the second bearing collar.

9. The slack adjuster of claim 8, wherein the second bearing collar defines a center opening through which a portion of the rod assembly extends, and wherein the second bearing collar is a solid component between the center opening and the groove, free from any opening or holes.

10. The slack adjuster of claim 8, wherein the groove in the first bearing collar defines an inner edge having a radius greater than or equal to about ⅛th of an inch, and wherein the groove in the second bearing collar also defines an inner edge having a radius greater than or equal to about ⅛th of an inch.

11. The slack adjuster of claim 4, further comprising

a pawl box including at least one locator tab and at least one coupling projection, wherein the tube defines at least one pawl opening adjacent to the nut of the nut assembly and at least one locator opening positioned adjacent to the at least one pawl opening, wherein the pawl box is attached to the tube by positioning the pawl box over the at least one pawl opening such that the at least one locator tab of the pawl box extend into the at least one locator opening and by forming the at least two coupling projections of the pawl box around an outer surface of the tube.

12. The slack adjuster of claim 1, further comprising

an end cap defining a groove extending generally along the circumferential direction, at least a portion of the rod assembly slidably extending through the end cap, wherein at least a portion of the tube is crimped into the groove in the end cap attaching the tube to the end cap.

13. A slack adjuster for a railroad car braking system defining an axial direction and a circumferential direction, the slack adjuster comprising:

a first jaw and a second jaw, the first jaw positioned at a first end of the slack adjuster along the axial direction and the second jaw positioned at a second end of the slack adjuster along the axial direction;

a rod assembly attached to the first jaw and extending generally along the axial direction;

a tube attached to the second jaw and also extending generally along the axial direction; and

a nut assembly configured to transfer a force between the rod assembly and the tube, the nut assembly including a first bearing collar defining a groove therein extending generally along the circumferential direction, at least a portion of the tube crimped into the groove in the first bearing collar attaching the tube to the first bearing collar.

14. The slack adjuster of claim 13, wherein the nut assembly further includes a second bearing collar also defining a groove therein extending generally along the circumferential direction, wherein at least a portion of the tube is crimped into the groove in the second bearing collar attaching the tube to the second bearing collar.

15. The slack adjuster of claim 13, wherein the second jaw includes a base defining a groove therein extending generally along the circumferential direction, wherein at least a portion of the tube is crimped into the groove in the base of the second jaw attaching the tube to the base of the second jaw.

16. A method for manufacturing a slack adjuster for a railroad car braking system, the slack adjuster defining an axial direction, the method comprising:

attaching a first jaw to a rod assembly;

positioning a nut assembly over a threaded portion of the rod assembly;

attaching the nut assembly to a tube extending generally along the axial direction such that at least a portion of the nut assembly is fixed along the axial direction relative to the tube; and

attaching the tube to a base of a second jaw by crimping a portion of the tube into a groove defined in the base of the second jaw, fixing the base of the second jaw to the tube.

17. The method of claim 16, wherein the nut assembly includes a nut defining a threaded opening rotatably engaged with the threaded portion of the rod assembly, a first bearing collar, and a second bearing collar, wherein attaching the nut assembly to the tube includes attaching the nut assembly to the tube by crimping at least a portion of the tube into a groove defined in an outer surface of the first bearing collar and crimping at least a portion of the tube into a groove defined in an outer surface of the second bearing collar.

18. The method of claim 16, wherein attaching the tube to the base of the second jaw by crimping a portion of the tube into the groove defined in the base of the second jaw includes crimping a portion of the tube into the groove defined in the base of the second jaw using a plurality of crimp dies, wherein each of the plurality of crimp dies includes a crimping portion, and wherein each of the crimping portions define a crimping edge having a radius of at least ⅛th of an inch.

19. The method of claim 16, further comprising:

reconditioning the slack adjuster, wherein reconditioning the slack adjuster includes removing the second jaw from the tube by shearing off the portion of the tube crimped into the groove in the base of the second jaw with a plurality of crimp dies.

20. The method of claim 16, further comprising:

attaching a pawl box to the tube, wherein attaching the pawl box to the tube includes positioning the pawl box over a pawl opening defined in the tube such that at least one locator tab of the pawl box extends into at least one locator opening defined in the tube, and wherein attaching the pawl box to the tube further includes forming a pair of coupling projections around an outer surface of the tube.