Patent Grant
7258243
This application is closely related to U.S. Pat. No. 6,446,820 entitled “Railcar Draft Gear Assembly and System” and its disclosure is hereby incorporated by reference thereto.
The present invention relates, in general, to draft gear assemblies for use in absorbing both buff and draft shocks normally encountered by railway rolling stock during make-up and operation of a train consist on a track structure and, more particularly, this invention relates to a draft gear assembly using elastomeric resilient compression material for absorbing both buff and draft shocks.
The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
Draft gear assemblies are widely used in United States railway industry to provide protection to a railway car by absorbing shocks in both draft and buff conditions.
The draft gears are installed in alignment with a railway car center sill and typically include a housing having a closed rear end and an open front end, a compressible cushioning means positioned within the closed rear end and a friction cushioning element adopted in the front end and associated with a spring release mechanism for continuously urging the friction cushioning element outwardly from the compressible cushioning means thereby releasing such friction cushioning element after compression of such draft gears.
The commonly used compressible cushioning means is typically either of an all spring configuration as taught by U.S. Pat. Nos. 5,152,409, 5,590,797 and 6,488,162 or of a spring and hydraulic assembly combination as taught by U.S. Pat. No. 3,368,698.
Lately, a new type of draft gear assembly utilizing an elastomeric energy absorbing material has been introduced into service. A particular type of such draft gear assembly, called Twin-Pac, taught by U.S. Pat. No. 6,446,820, utilizes elastomeric pad stacks for absorbing shocks in both draft and buff conditions.
This design includes a rear compressible resilient member disposed between a rear follower and a yoke portion and a front compressible resilient member disposed within the yoke and associated with a coupler follower. A center rod extends through the yoke portion, through the rear compressible resilient member and through the rear follower. Both the front and rear compressible resilient members are comprised of a stack of elastomeric pads. The design does not utilize a steel housing and steel friction members, thus resulting in reduced draft gear assembly weight.
In draft, only the front stack of pads is loaded, as yoke is moving toward the coupler follower which is abutting a pair of front stops, however in buff, both stacks of pads are loaded as the coupler follower is first moving toward the yoke and further causing the yoke to move in a direction of the rear follower which is abutting a pair of rear stops. This design allows for a different amount of draft and buff travel but still falls within the 6.5-inches of total travel required by the AAR M-901 specification. The integral yoke portion can be configured for interface with an E-coupler, an F-coupler, or a rotary dump type coupler.
Testing of the Twin-Pac draft gears according to paragraphs 6.0 and 9.0 of AAR standard M-901G-00 and involving two 70-ton nominal capacity covered hopper cars loaded to maximum gross weight of 220,000 pounds with dry sand resulted in draft gears failure at a speed being over 8 miles per hour and coupler force approaching 1,000,000 pounds. Event though the speed and force parameters exceed requirements of the AAR standard M-901G-00, it is well known that they are applicable during operation on the track.
It has been determined that the draft gear assembly failure was due to over-compression of the elastomeric pad stacks.
Since the design offers an advantage of reduced weight, it is desirable to provide an overtravel protection preventing over-compression of the elastomeric pad stacks and enabling a more reliable operation of the draft gear assembly.
U.S. Pat. No. 5,312,007 to Kaufhold et al. entitled “Slackless Railway Coupler With Draft/Buff Gear” discloses use of the rear compressible resilient member to absorb impact energy during buff conditions in combination with a plurality of guide bars for limiting the compression of the rear compressible resilient member. However, the slackless type coupler does not utilize the yoke as disclosed in U.S. Pat. No. 6,446,820 and does not utilize the front resilient compression member to absorb impact energy in draft conditions.
Therefore, it is desirable to provide an overtravel protection preventing over-compression of the elastomeric pad stacks in both buff and draft conditions.
It is further desirable to achieve such overtravel protection in the most economical method of retrofitting existing draft gears.
The present invention discloses a draft gear assembly for cushioning buff and draft shocks in a railway car having a coupler member, with such draft gear assembly being disposed within a center sill of such railway car intermediate a pair of front stops and a pair of rear stops. The draft gear assembly includes a yoke with a back wall and a top and a bottom walls extending from the back wall toward the front end of the draft gear assembly, which is disposed adjacent the coupler.
A coupler follower is disposed intermediate the back wall of the yoke and the front end of the draft gear assembly and includes a pair of stop contact surfaces for contact with such center sill front stops and a coupler bearing surface disposed intermediate the stop contact surfaces.
A front compressible resilient member is disposed intermediate the coupler follower and the back wall of the yoke. The front compressible resilient member has a pair of front end elastomeric pads and a plurality of intermediate front elastomeric pads.
A rear compressible resilient member is disposed intermediate the back wall of the yoke and the back end of the draft gear assembly and has a plurality of rear elastomeric pads.
A rear follower is positioned rearward of the rear compressible resilient member.
A center rod may be extending through the rear compressible resilient member and the rear follower and engaging a shortening member.
The draft gear assembly is provided with overtravel protection capability for limiting compression of the rear and front compressible resilient members.
In a first aspect, such overtravel protection includes a plurality of corner stops extending from either the back wall of the yoke or the rear follower for limiting compression of the rear compressible resilient member during buff travel to a distance being equal to full buff travel distance of the draft gear assembly. Such corner stops maybe further extended toward the coupler follower for limiting compression of the front compressible resilient member during draft travel to a full draft travel distance of the draft gear assembly.
In a second aspect, such overtravel protection includes a center rod having a larger middle portion extending through the rear compressible resilient member with a shoulder portion for limiting compression of the rear compressible resilient member during buff travel. Such rod may be further extended into the yoke toward the coupler follower for limiting compression of the front compressible resilient member during draft travel.
In the third aspect, such overtravel protection includes a plurality of stop members attached either internally or externally to each elastomeric pad of the front and rear compressible resilient members.
In a forth aspect, such overtravel protection includes stop members attached to the sides of the center sill external to the rear resilient compression member and engageable with the yoke.
It is therefore one of the primary objects of the present invention is to provide a draft gear assembly which protects a railway car by absorbing shocks in both draft and buff conditions.
A further object of the present invention is to provide a draft gear assembly having a front and rear elastomeric compressible resilient members.
Another object of the present invention is to provide a draft gear assembly having positive means for limiting compression of the front and rear elastomeric compressible resilient members.
Additional object of the present invention is to provide a draft gear assembly with a front and rear elastomeric compressible resilient members having more reliable operation.
Yet additional object of the present invention is to provide economical means of retrofitting existing draft gear assemblies to limit compression of the front and rear elastomeric compressible resilient members.
These and various other objects and advantages to the present invention will become more apparent to those persons skilled in the relevant art from the following more detailed description, particularly, when such description is taken in conjunction with the attached drawings and the appended claims.
Prior to proceeding to the more detailed description of the present invention, it should be noted that for the sake of clarity identical components, having identical functions have been identified with identical reference numerals throughout the several views, which have been illustrated in the drawing figures.
The draft gear assembly of the present invention overcomes the aforementioned disadvantages by incorporating overtravel protection means disposed within the draft gear assembly or attached to the side walls of the center sill of the railway car for enabling compression of the compressible resilient members that does not exceed predetermined full buff and draft travel distances.
The illustrated embodiments show that the draft gear assembly of the present invention may be used with standard E-couplers and rotary dump couplers, as well as with couplers having E coupler heads and F shanks, for example. For the sake of brevity, the following description will be concerned with the draft gear assembly for use with standard E-coupler as those skilled in the art will readily understand that operation of the draft gears for use with other coupler types will be identical except for configuration of the yoke and coupler followers.
To help the reader in understanding the present invention, a prior art draft gear assembly, generally designated 10, for use with a standard E-coupler is illustrated in
Each front end elastomeric pad member 34, as shown in
As shown in
The draft gear assembly of the present invention, generally designated 100, including overtravel protection means, generally designated 200, is best shown in
It will be appreciated that such first predetermined distance 206 is equal to a predetermined full buff travel distance of the draft gear assembly 100.
It is preferred that such at least one rear stop member 202 is a plurality of rear stop members 202 rigidly attached to the back wall 104, preferably at each corner thereof, and engaging opposed corners of the rear follower 106. Such disposition of the rear stop members 202 will enable to maintain a second predetermined cross-section of the draft gear assembly 200 to fit a standard draft gear pocket (not shown). It is further preferred that such plurality of rear stop members 202 is integral to the yoke 102.
Those skilled in the art will readily understand that such plurality of rear stop members 202 may be rigidly attached by fastening or welding methods or integral to the rear follower 106 and engage the back wall 104 during buff travel.
At least a pair of adjacent rear stop members 202 may be adapted with a laterally disposed at least one structural reinforcing means 205, best illustrated in
In a similar arrangement, either the yoke 102 or the coupler follower 109 is adapted with at least one front stop member 207 having an end 208 disposed at a second predetermined distance 209 from the back surface of the coupler follower 109 or the back wall 104 of the yoke 102. Such second predetermined distance 209 is equal to a predetermined full draft travel distance of the draft gear assembly 100. The at least one front stop member 207 has a third predetermined cross-section to cooperate with notched corners of a front resilient member 120 enabling to maintain such second predetermined cross-section of the draft gear assembly 200.
Those skilled in the art will readily understand that, in buff conditions, the yoke 102 will be positively stopped with respect to the rear follower 106 by the rear stop members 102 and the coupler follower 109 will be positively stopped with respect to the yoke 102 by the front stop members 207. In draft condition, only the yoke 102 will be positively stopped with respect to the coupler follower 109 by the front stop members 207.
In a further preferred embodiment of the present invention, best illustrated in
In the first alternative embodiment of the present invention, best illustrated in
In further reference to
In the second alternative embodiment of the present invention, best illustrated in
The center rod 227 may be further provided with a third portion 232 extending into the yoke 102 and having an end disposed at such second predetermined distance 209 from the coupler follower 109.
Those skilled in the art will readily understand that at least one, but preferably a plurality of rod members 227 may be disposed intermediate back wall 104 and rear follower 106 at a corner or corners of the draft gear assembly 100.
The overtravel protection means 200 of the third alternative embodiment, best illustrated in
To control the draft travel distance, the overtravel protection means 200 may include at least one second external stop member 264, best illustrated in
The overtravel protection means 200 of the forth alternative embodiment, best illustrated in
Although a presently preferred and various alternative embodiments of the present invention have been described in considerable detail above with particular reference to the drawing FIGURES, it should be understood that various additional modifications and/or adaptations of the present invention can be made and/or envisioned by those persons skilled in the relevant art without departing from either the spirit of the instant invention or the scope of the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2776057 | Blattner | Jan 1957 | A |
| 3403790 | Zanow | Oct 1968 | A |
| 3598249 | Vickerman | Aug 1971 | A |
| 3712479 | Atkinson | Jan 1973 | A |
| 3741406 | Anderson | Jun 1973 | A |
| 5312007 | Kaufhold et al. | May 1994 | A |
| 6446820 | Barker et al. | Sep 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 853774 | Jan 1959 | GB |
| Number | Date | Country | |
|---|---|---|---|
| 20060043044 A1 | Mar 2006 | US |
