Patent Grant
7097055
This application is closely related to co-pending U.S. application Ser. No. 10/927,911 filed on Aug. 27, 2004 and entitled “Housing for Long Travel High Capacity Friction Draft Gear Assembly”, to co-pending U.S. application Ser. No. 10/927,910 filed on Aug. 27, 2004 and entitled “Long Travel High Capacity Friction Draft Gear Assembly”, filed concurrently herewith. These applications are assigned to the assignee of the present invention and the disclosures of these copending applications are incorporated herein by reference thereto.
The present invention relates, in general, to friction-type draft gear assemblies for use in cushioning 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 friction-type draft gear assembly having a longer travel distance in buff condition and, yet more particularly, the instant invention relates to a friction-type draft gear assembly having an integral yoke portion for direct attachment to a coupler of the railway car.
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.
Friction type draft gear assemblies widely used in United States railway industry to provide protection to a railway car by absorbing shocks in both draft and buff conditions must meet various Association of American Railroads (AAR) requirements. In one aspect draft gear must be capable of maintaining the minimum shock absorbing capacity during its service life required by AAR standard M-901-G to be at least 36,000 foot pounds being measured during a drop hammer test. In the other aspect AAR mandates working action of such draft gear to be achieved without exceeding a 500,000 pound reaction pressure acting on the freight car sills in order to prevent upsetting the coupler shank. In a further aspect, the draft gear must fit into a standard AAR railway car pocket of 24.625 inches in length.
The commonly used draft gears, installed in alignment with a railway car center sill, include a housing having an open front and a closed rear portions. A compressible cushioning means is positioned within the rear portion of the housing. A friction cushioning element is adopted in the front portion of the housing. The draft gears further include 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 compressible cushioning means is typically either of an all spring configuration as taught by U.S. Pat. Nos. 5,152,409 and 5,590,797, of a spring and hydraulic assembly combination as taught by U.S. Pat. No. 3,368,698, or of an elastomeric pad stack as taught by U.S. Pat. Nos. 6,488,162 and 6,446,820.
All standard steel housing draft gears presently fitting in the AAR standard 24.625-inch pocket have a nominal 3.25-inches of travel. This travel applies to each buff and draft conditions for a total travel distance of 6.50-inches. This 6.50-inches of total travel is spelled out in the various M-901 specifications. The only exception presently on the market is an all elastomeric device called the Twin-Pac as taught by U.S. Pat. No. 6,446,820. This design uses a housing with integral yoke and two different stacks of elastomeric pads divided by a spacer plate. In draft only the front stack of pads is loaded, however in buff both stacks of pads are loaded. 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 specification. Because the resilient compression members in the Twin-Pac draft gear are made exclusively from elastomeric material, the design has several drawbacks, including high recoil forces that cause the cars to bounce back and forth during an impact. This bouncing is also possible in normal train line action. Additionally, testing indicated that such draft gear assembly was damaged during testing when subjected to a higher buff impact loads which are applicable during operation of the railway vehicle.
Therefore, in the first aspect, it is desirable to provide a friction draft gear assembly with an integral yoke portion having a more reliable operation.
In most, if not all cases, impact energy levels during buff conditions are much higher than the train line energy levels during draft conditions. Therefore, in the second aspect, it would be appreciated that any device used to control energy should be able to absorb more energy in buff rather then in draft while fitting into AAR standard 24.625-inch pocket.
The present invention provides a friction draft gear assembly for railway car stock having a higher shock absorbing capacity, having a 4.75 inch buff travel distance, a 1.25 inch draft travel distance and an integral yoke portion while fitting into a standard 24.625 inch long draft gear pocket within the center sill. The draft gear assembly comprises a housing closed at one end and open at the opposed end. The housing has a dual rear chamber adjacent the closed end and a front chamber adjacent the open end which is in open communication with the dual rear chamber. The dual rear chamber enables employment of the longer spring elements to achieve a buff travel of 4.75 inches and, more importantly, to achieve such buff travel of 4.75 while fitting into the draft gear pocket. A yoke portion extends from the open end and contains either a pair of key slots or a pair of key holes for attachment to the coupler. A pair of apertures is provided adjacent the yoke portion for enabling travel of a coupler follower during friction draft gear assembly operation.
A compressible cushioning element extends longitudinally from the second rear portion toward the open front end and may be at least one spring, a hydraulic assembly, a well known elastomeric pad stack or any combination thereof.
The friction draft gear assembly has a pair of laterally spaced opposed friction surfaces located in the front chamber of the housing.
A seat means with at least a portion of one surface thereof abutting the opposite end of the hydraulic compressible cushioning means is mounted to move longitudinally within the housing for respectively compressing and releasing the hydraulic compressible cushioning means during application and release of a force on the draft gear assembly.
A friction cushioning means is positioned at least partially within the front chamber of the housing for absorbing energy during application of a force sufficient to cause a compression of the draft gear assembly. The friction cushioning means includes a pair of laterally spaced stationary outer plates, which have an outer friction surface engaging the laterally spaced friction surfaces carried by the housing. The outer friction surface includes at least one recessed area to reduce the frictional surface engaging area between the stationary outer plate and the laterally spaced friction surface carried by the housing, and at the same time decrease relative movement between such stationary outer plate and the housing.
A pair of laterally spaced movable plates having at least a portion of an outer friction surface movably and frictionally engaging an inner friction surface of the stationary outer plate and one edge engaging the seat means.
A pair of laterally spaced tapered stationary plates have an outer friction surface movably and frictionally engaging at least a portion of an inner friction surface of the movable plate.
A pair of laterally spaced wedge shoes having at least a portion of an outer friction surface movably and frictionally engaging at least a portion of an inner friction surface of the tapered stationary plate and at least a portion of one edge engaging the seat means. The pair of wedge shoes have a first predetermined tapered portion of 4.5 degrees engaging the matching tapered portion of the stationery tapered plates.
A center wedge having a pair of matching predetermined tapered portions of 45 degrees for engaging a second tapered portion of the wedge shoe to initiate frictional engagement of the friction cushioning means and thereby absorb energy.
A spring release means engaging and longitudinally extending between the seat means and the center wedge for continuously urging the friction cushioning means outwardly from the compressible cushioning means to release such friction cushioning element when an applied force compressing the draft gear is removed.
A coupler follower is disposed within the yoke portion during the friction draft gear assembly being in the draft condition and is adapted for movement within the follower apertures of the housing during buff travel to engage the pair of laterally spaced movable plates and the center wedge to absorb the shock energy of the railway car.
It is therefore one of the primary objects of the present invention is to provide a friction 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 friction draft gear assembly having a higher shock absorbing capacity which meets existing AAR standards.
Yet a further object of the present invention is to provide a friction draft gear assembly having more reliable operation.
Another object of the present invention is to provide a friction draft gear assembly having a higher shock absorbing capacity while fitting into a 24.62 inches long pocket.
Yet another object of the present invention is to provide a friction draft gear assembly having a longer travel in a buff condition and a shorter travel in a draft condition that incorporates integral yoke portion.
Additional object of the present invention is to provide a friction draft gear assembly having an integral yoke portion that does not utilize an all elastomeric resilient compression elements.
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.
a–2c are a longitudinal cross-sectional view of a friction draft gear assembly of the present invention along lines 2—2 in
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 present invention enables a higher shock absorbing capacity of the draft gear assembly fitting into a 24.62 inch long pocket by employing a novel housing construction having an extended rear portion enabling adaptation of a longer spring design which results in a longer buff travel in combination with an integral yoke portion and novel coupler follower to achieve shorter draft travel than friction draft gear assemblies presently in use.
To accommodate increased buff travel of 4.75 inches in the standard pocket, the coupler follower thickness was decreased to prevent coupler knuckle from hitting the striker and its front portion was further decreased to extend into the yoke portion and occupy the space of the coupler butt. This coupler follower modification also required the yoke's key slot to be moved forward giving the extra horn clearance required for the extra buff travel. Such forward movement of the coupler follower enabled the friction draft gear assembly of the present invention to accommodate additional buff travel in the standard pocket.
To reduce the amount of draft travel from 3.25 inches to between 1.250 and 1.750 inches, all four corners of the coupler follower were notched out. Consequently, all four outside corners of the open end of the housing were extended in a way enabling them to pass the coupler follower's notched corners. When the friction draft gear assembly is in full draft, the housing then contacts the front stops limiting the total draft travel. In full buff, the coupler follower passes between the four extensions located on the housing corners and contacts the housing in a manner identical to that of a standard friction draft gear assemblies presently in use.
Referring to the present invention, as shown in
A pair of rear ledge members 204 having a first predetermined width are disposed intermediate the first and second rear portions 202 and 206 respectively and abut the pair of the rear stops 106. Such pair of rear ledge members 204 enables the second rear portion 206 of the closed end to extend into such sill 100 past the working surface 107 of the rear stops 106. It will be appreciated that such second rear portion 206 will be at least partially disposed intermediate such rear stops 106.
A first front portion 210 of the open end of the housing 200 having a third predetermined cross-section and a forth predetermined length is disposed adjacent the first rear portion 202. Such front first portion 210 is axially opposed to the closed end and is maintained in open communication therewith. Preferably, such third predetermined cross-section is equal to the first predetermined cross-section of the first rear portion 202. The first front portion 210 contains a pair of opposed first follower apertures 220 having a fifth predetermined length and a first predetermined height.
A second front portion 216 extends outwardly from the first front portion 210 and contains a pair of oppositely disposed vertical side members 218. Each vertical side member 218 contains a second follower aperture 222 of a sixth predetermined length and a second predetermined height and a longitudinally disposed aperture 224 for attachment to coupler arm 112 with a standard coupler key 120.
Preferably, a pair of oppositely disposed horizontal surfaces 217 is provided intermediate the vertical side members 218 forming a box like structure, best illustrated in
Those skilled in the art will readily understand that a pair of opposed round apertures (not shown) may be disposed within such horizontal surfaces 217 for attachment to a coupler 109 being of a standard F-shank coupler with a coupler pin (not shown) being vertically disposed.
A pair of front ledge members 211 having a second predetermined width are disposed intermediate the first and second front portions 210 and 216 respectively and abut the working surface 105 of each of the front stops 104 with the friction draft gear assembly 10 being in a full draft position.
A coupler follower 230 has a first portion 232 of a first predetermined thickness with an inner surface 234 engageable with the end of a pair of laterally spaced movable plates 50 and the center wedge 72 of the friction draft gear assembly 10 and opposed outer surface 236 engageable with the working surface 105 of each of the front stops 104. Opposed ends 238 of the first portion 232 are provided with at least one, but preferably four, corner apertures 240 to fit within the pair of first follower apertures 220 during buff travel.
A second portion 242 fitting intermediate the pair of the vertical side portions 218 abuts the outer surface 236 at the first surface and has a second surface 240 engageable with the coupler arm 114 and the pair of front stops 104.
In a particular reference to
The compressible cushioning means 18 may comprises at least one cushioning spring and a hydraulic assembly as taught by U.S. Pat. No. 3,368,698, or at least one elastomeric pad stack as taught by U.S. Pat. No. 6,488,162 and U.S. Pat. No. 6,446,820, but preferably the compressible cushioning means 18 comprises at least one cushioning spring 28 of a predetermined length, and, yet more preferably, the compressible cushioning means 18 comprises a pair of first and second resilient compression means, being a pair of first and second spring elements 28 and 28a respectively, best shown in
A seat means 24 abutting the pair of first and second springs 28 and 28a respectively is adapted within the housing 200 for longitudinal movement therein for respectively compressing and releasing the compressible cushioning means 18 during application and release of a force on the draft gear assembly 10.
The housing 200 further includes a compressible cushioning means 18 positioning means 214 disposed adjacent the inner surface 212 of the bottom wall 208 for maintaining that end of the compressible cushioning means 18 centrally located within the second rear portion 206 of the housing 200 during compression and extension of such compressible cushioning means 18.
A friction cushioning means, generally designated as 42, is disposed at least partially within the front portion 210 of the housing 200. The friction cushioning means 42 absorbs energy during application of a force sufficient to cause a compression of the draft gear assembly 10.
The friction cushioning means 42 includes a pair of laterally spaced outer stationary plates 44 having an inner friction surface 48 and an opposed outer surface 46 engaging the housing 12.
The pair of laterally spaced movable plates 50 of substantially uniform thickness having an outer friction surface 52 and an inner friction surface 54 and at least one substantially flat edge 56 intermediate the outer friction surface 52 and an inner friction surface 54 is disposed within the open end of the draft gear assembly 10. The inner friction surface 54 having an edge 56 thereof engaging the seat means 24. At least a portion of the outer friction surface 52 movably and frictionally engages the inner friction surface 48 of the outer stationary plate 44.
A pair of laterally spaced tapered plates 58 having an outer friction surface 60 and an opposed inner friction surface 62 are adapted adjacently such movable plates 50. The outer friction surface 60 movably and frictionally engages at least a portion of the inner friction surface 54 of the movable plate 50.
The friction cushioning means 42 further includes a pair of laterally spaced wedge shoes 64 which have at least a portion of an outer friction surface 66 movably and frictionally engaging at least a portion of the inner friction surface 62 of the tapered stationary plate 58. Wedge shoes 64 have at least a portion of one edge 68 engaging seat means 24 and a predetermined tapered portion 70 on an opposed edge thereof.
It has been discovered that the tapered portions 62 of the tapered plates 58 and the tapered portions 66 of the wedge shoe 64 which are tapered upwardly and outwardly from a plane substantially parallel to the longitudinal centerline of the draft gear assembly 10 must be controlled within a very close tolerance of between about 4 degrees and 5 degrees, with the optimum of generally 4.5 degrees when the compressible cushioning means 18 is a pair of the first and second springs 28 and 28a respectively.
The center wedge 72 having a pair of matching tapered portions 74 for engaging the tapered portion 70 of the wedge shoe 64 is provided to initiate frictional engagement of the friction cushioning means 42. The tapered portions are tapered at an angle of approximately 49.0°–50.0°, preferably at an angle of 49.5°.
The draft gear assembly 10 additionally includes a spring release means 76 engaging and extending longitudinally between the seat means 24 and the center wedge 72 for continuously urging the friction cushioning mean 42 outwardly from the compressible cushioning means 18 to release the friction cushioning means 42 when an applied force compressing the draft gear assembly 10 is removed.
In operation upon impact into a coupler knuckle 110, the buffing shock is transmitted from the coupler arm 112 through the coupler follower 230 to the central wedge 72, causing it to act through the wedge shoes 64 and thereby compress all of the cushioning elements simultaneously. These parts will furnish sufficient cushioning for light buffing shocks. After a suitable travel, however, the coupler follower 230 will abut the outer ends of the movable plates 50 introducing energy-absorbing friction between the movable plates 50 and the stationary plates 58 and 44 which have been pressed together by the action of the wedge shoes 64. As this action continues, the pressure between the adjacent surfaces of the intercalated plates has been enormously increased due to the fact that the wedge shoes 64 are loaded against the cushioning mechanism 42. The energy absorption and dissipation through friction and compression of the cushioning mechanism continues until the gear is closed including compression of cushioning element 18.
During release of the friction draft gear assembly 10, the compressible cushioning means 18 is maintained in alignment by the seat means 24.
To enable a longer buff travel 250 of 4.75 inches, in a first aspect, the closed rear end has been extended into the center sill 100. In the second aspect, the portions of the standard coupler follower that abut front stops 104 were reduced in thickness by 1.250 inches to prevent the coupler 109 from hitting the striker (not shown) of the railway vehicle (not shown), thus forming the first portion 232. In the third aspect, the longitudinally disposed apertures 224 were shifter forward toward the coupler knuckle 110 by a predetermined distance enabling additional horn clearance 122 required by the extra buff travel.
To enable a shorter draft travel 252 of 1.250 inches to 1.750 inches, a plurality of corner apertures 240 were provided within the coupler follower 230 enabling thereof to travel within the first follower apertures 220 during buff travel and to contact a bottom wall 221 thereof at the end of the full buff travel thus achieving a contact with the housing 200 similarly to operation of the presently used friction draft gear assemblies manufactured by the assignee of the present invention. Additionally, when the friction draft gear assembly 10 is in full draft, the front ledge portions 211 of the second open end contact working surfaces 105 of the front stops 104 to limit the total draft travel.
Finally, the lengths of friction components and compressible cushioning means 18 were selected to match the housing 200 and coupler follower 230 of the present invention.
It will be appreciated that a combined buff and draft travel of the friction draft gear assembly of the present invention is equal to or less than 6.50 inches thus meeting requirements of various M-901 specifications.
Those skilled in the art will readily understand that the friction draft gear assembly having and integrated yoke portion and having equal buff and draft travel will be manufactured according to the aforementioned embodiments of the present invention. Such friction draft gear assembly, generally designated 11, best shown 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 |
|---|---|---|---|
| 3447693 | Cardwell | Jun 1969 | A |
| 4305514 | Zanow et al. | Dec 1981 | A |
| 5529194 | Merker et al. | Jun 1996 | A |
| 5590797 | Duffy et al. | Jan 1997 | A |
| 6446820 | Barker et al. | Sep 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 947333 | Jan 1964 | GB |
| WO 2005073047 | Aug 2005 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20060043045 A1 | Mar 2006 | US |
