Railcar draft gear assembly

A railcar draft gear assembly specifically designed to consistently and repeatedly withstand up to about 110,000 ft-lbs of energy imparted thereto while not exceeding a force level of 900,000 lbs. and while having a wedge member of the draft gear assembly travel in an inward axial direction of less than about 4.5 inches relative to an open end of the draft gear.

FIELD OF THE INVENTION DISCLOSURE

This invention disclosure generally relates to railcar draft gears and, more specifically, to a railcar draft gear assembly specifically designed to consistently and repeatedly withstand up to about 110,000 ft-lbs of energy imparted thereto while not exceeding a force level of 900,000 lbs. while having a wedge member of the draft gear assembly travel in an inward axial direction approximating 4.5 inches relative to an open end of the draft gear.

BACKGROUND

As railroads push to increase car capacity to handle the increasing demands on the transportation network, freight car designers/builders have been stepping up to the challenge. With the overall train lengths limited by system constraints such as passing siding lengths, the challenge has been how to achieve more railcar capacity in the same or shorter lengths of freight cars and trains. Freight car designers/builders have heretofore met this challenge by pushing the top and bottom of the defined clearance line envelopes to the limits allowed by the Association of American Railroads (the “AAR”). Additionally, car designers/builders have utilized modern design tools to make freights car designs lighter in weight, while still meeting the AAR standard design loads whereby allowing each freight car to carry more lading while maintaining maximum allowable gross rail loads.

During the process of assembling or “making-up” a freight train, railcars are run into and collide with each other to couple them together. Since time is money, the speed at which the railcars are coupled has significantly increased. Moreover, and because of their increased capacity, the railcars are heavier than before. These two factors and others have resulted in increased damages to the railcars when they collide and, frequently, to the lading carried within such railcars.

Providing an energy absorption/coupling system at opposed ends of each railcar has long been known. Such a system typically includes a coupler for releasably attaching two railcars to each other and a draft gear assembly arranged in operable combination with each coupler for absorbing, dissipating and returning energy imparted thereto during make-up of the train consist and during operation of the railcar. As railroad car designer/builders have reduced the weight of their designs, however, they have also identified a need to protect the integrity of the railcar due to excessive longitudinal loads being placed thereon, especially as the railcars are coupled to each other. Such longitudinal loads frequently exceed the design loads set by the AAR.

While conventional draft gears have high shock absorbing capacities and capabilities, they tend to transmit a high magnitude of force to the railcar structure during a work cycle. Of course, transmitting a high magnitude of force to the railcar structure can result in damages to the goods being carried by the railcar and the railcar itself.

A conventional draft gear assembly is disposed within a pocket defined by a centersill on the railcar and has an operative length of travel in one direction of movement of about 3.5 inches before solid stops limit the travel and no more energy can be absorbed by the draft gear. Over this limited distance, the energy of the moving railcar must be absorbed so as to reduce the impact forces and resulting damage to the adjacent railcar to be coupled thereto. Largely because of their increased coupling speeds and the increased weights of the loads being carried thereby, heretofore known energy absorption/coupling systems have been shown to be inadequate. As such, railcars are experiencing severe end-impacts that can cause a complete collapse of the end of the car—resulting in large repair costs—coupled with damage to the lading—resulting in significantly higher insurance premiums.

Increasing the travel of the draft gear assembly may advantageously allow more energy to be absorbed. The challenge of increasing the travel of the draft gear assembly is, however, complicated. Passing sidings and loading facilitates often limit the number of railcars that can be joined to each other in one train. Lengthening the draft gear housing also means lengthening the size or length of the pocket wherein the draft gear assembly is accommodated which requires lengthening the centersill resulting in adding length to the railcar. The length of a railroad car, however, is critical.

By itself, adding to the length of the railcar does not appear problematical. When considering, however, that the railcars are not transported individually but rather as part of a much longer train consist, increasing the length of a single railcar is exponentially multiplied when considering the cumulative or overall length of a 100 railcar train consist. Increasing the length of an individual railcar can result in the last railcar in a 100 car consist no longer fitting on the siding and, thus, having to be left behind. As such, there would be at least a one percent (1%) loss in train efficiency. This is simply unacceptable. Accordingly, the concept of simply increasing the length of the draft gear assembly to solve the problem of energy absorption between railcars is unacceptable to the railroad industry.

Thus, there is a continuing need and desire for a draft gear assembly which not only allows for increased travel over which the high level of energy from impact loads of colliding railcars can be absorbed, dissipated and returned but the overall length of the draft gear assembly housing cannot be lengthened and the draft gear assembly must be capable of absorbing the increased impact loads being realized in today's railroad industry.

SUMMARY

In view of the above, and in accordance with one aspect of this invention disclosure, there is provided a draft gear assembly including a hollow metal housing open at a first end and closed toward the second end thereof. The housing is configured to fit within a standard sized pocket defined by the centersill on the railcar. The housing defines a series of tapered longitudinally extended inner surfaces opening to and extending from the first end of the housing. A series of friction members are equally spaced about a longitudinal axis of the draft gear assembly toward the first end of the housing, with each friction member having axially spaced first and second ends and an outer surface extending between the ends. The outer surface on each friction member is operably associated with one of the tapered longitudinally extended inner surfaces on the housing so as to define a first angled friction sliding surface therebetween.

A wedge member is arranged for axial movements relative to the first end of the housing and to which external forces are applied during operation of the railcar. The wedge member defines a series of outer tapered surfaces equally spaced about the longitudinal axis of the housing and equal in number to the number of friction members. In one form, each outer tapered surface on the wedge member is operably associated with an inner surface on each friction member so as to define a second angled friction sliding surface therebetween and such that the wedge member produces a radially directed force against the friction members upon movement of the wedge member inwardly of the housing. A spring seat is arranged within the housing. One surface of the spring seat is arranged in operable engagement with the second end of each friction member.

A spring assembly is disposed in the housing between the closed end of the housing and a second surface of the spring seat for storing, dissipating and returning energy imparted to the draft gear assembly. The spring assembly includes an axial stack of individual elastomeric springs. In one embodiment, the spring assembly, in operable combination with the disposition of the first and second angled sliding surfaces of the draft gear assembly relative to the longitudinal axis of the draft gear assembly, permits the draft gear assembly to consistently and repeatedly withstand about 70,000 ft-lbs. to about 85,000 ft-lbs. of energy imparted to the draft gear assembly while not exceeding a force level of 600,000 lbs. over a range of travel of the wedge member in an inward axial direction relative to the housing approximating 3.5 inches.

In accordance with this family of embodiments, the first angled friction sliding surface of the draft gear assembly is disposed at an angle ranging between about 1.5 degrees and about 5 degrees relative to the longitudinal axis of the draft gear assembly. Preferably, the second angled friction sliding surface of the draft gear assembly is disposed at an angle ranging between about 32 degrees and about 45 degrees relative to the longitudinal axis of the draft gear assembly. In one form, the elastomeric pad of each individual elastomeric spring is formed from a polyester material having a Shore D hardness ranging between about 40 and 60.

Preferably, the spring assembly of the draft gear assembly further includes a rigid separator plate disposed between two axially adjacent individual springs in the axial stack of elastomeric springs. The disposition of the separator plate creates different dynamic elastic absorption characteristics on opposite sides thereof whereby optimizing dynamic lost work opportunities during an impact event of the draft gear assembly.

According to another aspect of this invention disclosure there is provided a draft gear assembly including a hollow metal housing open at a first end and closed toward the second end thereof. The draft gear assembly housing is configured to fit within a standard sized pocket defined by the centersill on the railcar. The housing defines a series of tapered longitudinally extended inner surfaces opening to and extending from the first end of the housing. A series of friction members are equally spaced about a longitudinal axis of the housing toward the first end of the housing. Each friction member has axially spaced first and second ends and an outer surface extending between the ends. The outer surface on each friction member is operably associated with one of the tapered longitudinally extended inner surfaces on the housing so as to define a first angled friction sliding surface therebetween.

A wedge member is arranged for axial movements relative to the first end of the housing. External forces are applied to the wedge member during operation of the railcar. Toward an opposite end, the wedge member defines a series of equally spaced outer tapered surfaces. In one form, the outer tapered surfaces on the wedge member are operably associated with inner surfaces on the friction members so as to define a second angled friction sliding surface therebetween and such that the wedge member produces a radially directed force against the friction members upon movement of the wedge member inwardly of the housing. A spring seat is arranged within the housing. One surface of the spring seat is arranged in operable engagement with the second end of each friction member.

A spring assembly is disposed within and between the closed end of the housing and a second surface of the spring seat for storing, dissipating and returning energy imparted thereto. The spring assembly is configured to function in operable combination with the disposition of said first and second angled sliding surfaces of said draft gear assembly such that said draft gear assembly consistently and repeatedly withstands about 110,000 ft-lbs. of energy imparted to the draft gear assembly at a force level not to exceed 900,000 lbs. over a range of travel of the wedge member in an inward axial direction relative to the housing of at least 4.5 inches.

Preferably, the first angled friction sliding surface on the draft gear assembly is disposed at an angle ranging between about 1.5 degrees and about 5 degrees relative to the longitudinal axis of the draft gear assembly. In the preferred form, the second angled friction sliding surface is disposed at an angle ranging between about 32 degrees and about 45 degrees relative to the longitudinal axis of the draft gear assembly.

The spring assembly preferably includes an axial stack of individual elastomeric springs. Each spring includes an elastomeric pad having a generally rectangular shape, in plan, approximating the cross-sectional configuration of the hollow chamber defined by the housing whereby optimizing the capability of the spring assembly to store, dissipate and return energy imparted to the draft gear assembly by the coupler. The elastomeric pad of each individual elastomeric spring is preferably has a Shore D hardness ranging between about 40 and 60. Preferably, the spring assembly of the draft gear assembly further includes a rigid separator plate disposed between two axially adjacent individual springs in the axial stack of elastomeric springs to create different dynamic elastic absorption responses on opposite sides of the plate whereby optimizing dynamic lost work opportunities during an impact event of the draft gear assembly.

In another family of embodiments, there is provided a draft gear assembly including a hollow metal housing open at a first end and closed toward the second end thereof. The housing is configured to fit within a standard sized pocket defined by a centersill on a railcar. The housing defines a series of tapered longitudinally extended inner surfaces opening to and extending from the first end of the housing. A series of friction members are equally spaced about a longitudinal axis of the housing and are arranged toward the first end of the housing. Each friction member has axially spaced first and second ends and an outer surface extending between the ends. The outer surface on each friction member is operably associated with one of the tapered longitudinally extended inner surfaces on the housing so as to define a first angled friction sliding surface therebetween.

A wedge member is arranged for axial movements relative to the first end of the housing. External forces are applied to the wedge member during operation of the railcar. The wedge member defines a series of equally spaced outer tapered surfaces. In one form, each outer tapered surface on the wedge member operably associates with an inner surface on each friction member so as to define a second angled friction sliding surface therebetween. In operation, the wedge member produces a radially directed force against the friction members upon movement of the wedge member inwardly of the housing. A spring seat is arranged within the housing. One surface of the spring seat is arranged in operable engagement with the second end of each friction member.

A spring assembly is arranged between the closed end of the housing and a second surface of the spring seat for storing, dissipating and returning energy imparted to the draft gear assembly. The spring assembly of each draft gear assembly is configured and operates in operable combination with the first and second angled surfaces on the draft gear assembly such the draft gear assembly consistently and repeatedly withstands about 70,000 ft-lbs to about 110,000 ft-lbs. of energy imparted thereto while not exceeding a force level of 900,000 lbs. over a range of travel of wedge member in an inward axial direction relative to the housing of about 4.5 inches.

Preferably, the first angled friction sliding surface on the draft gear assembly is disposed at an angle ranging between about 1.5 degrees and about 5 degrees relative to the longitudinal axis of the draft gear assembly. In one form, the second angled friction sliding surface is disposed at an angle ranging between about 32 degrees and about 45 degrees relative to the longitudinal axis of the draft gear assembly.

In one embodiment, the housing of each draft assembly has two pairs of joined and generally parallel walls extending from the closed end toward the open end of the housing such that the walls define a hollow chamber having a generally rectangular cross-sectional configuration, in plan, for a major portion of the length thereof and which opens to the open end of the housing. Preferably, the spring assembly includes an axial stack of individual elastomeric springs, with each spring including an elastomeric pad having a generally rectangular shape, in plan, approximating the cross-sectional configuration of the hollow chamber defined by the housing whereby optimizing the capability of the spring assembly to store, dissipate and return energy imparted to the draft gear assembly. In a preferred embodiment, the elastomeric pad of each individual elastomeric spring has a Shore D hardness ranging between about 40 and 60.

In a preferred embodiment, the spring assembly of the draft gear assembly further includes a rigid separator plate disposed between two axially adjacent individual springs in the axial stack of elastomeric springs so as to create different dynamic elastic absorption reaction on opposite sides of the separator plate whereby optimizing dynamic lost work opportunities during an impact event of the draft gear assembly. In one form, a first group of springs, disposed to one side of the separator plate, have a different cumulative spring rate than a group of springs disposed to an opposite side of the separator plate. In this later embodiment, the group of springs disposed between the separator plate and the spring seat offer less resistance to axial compression than the group of springs disposed between the opposite side of the separator plate and the closed end of the housing.

DETAILED DESCRIPTION

While this invention disclosure is susceptible of embodiment in multiple forms, there is shown in the drawings and will hereinafter be described preferred embodiments, with the understanding the present disclosure is to be considered as setting forth exemplifications of the disclosure which are not intended to limit the disclosure to the specific embodiments illustrated and described.

Referring now to the drawings, wherein like reference numerals indicate like parts throughout the several views, there is shown inFIG. 1a railroad car draft gear assembly, generally identified by reference numeral10, and embodying teachings and principals of this invention disclosure. One of the many advantages of the draft gear assembly10of this invention disclosure being that it can be relatively easily installed without incurring any changes or modifications to a standard sized pocket12defined by a centersill14on a railcar16.

The centersill14can be cast or fabricated and has many standard features. As shown inFIG. 1, the centersill14has longitudinally or axially spaced front and rear stops15and17, respectively, connected to and carried by sidewalls (not shown) on the centersill14. The longitudinal distance between the inboard face of the front stop15and the inboard face of the rear stop is 24.625 inches.

As shown inFIG. 1, draft gear assembly10includes an axially elongated hollow and metallic housing20defining a longitudinal axis22. Housing20is closed by an end wall24(FIG. 4) at a first or closed end26and is open toward an axially aligned second or open end28.

In the embodiment illustrated inFIG. 2, housing20includes two pairs of joined and generally parallel walls30,30′ and32,32′, extending from the closed end26toward the open end28and defining a hollow chamber34within housing20(FIGS. 2 and 3). As shown inFIG. 2, the housing walls30,30′ and32,32′ provide the housing chamber34with a generally rectangular or box-like cross-sectional configuration, in plan, for a major lengthwise portion thereof.

Moreover, and as shown inFIG. 3, toward the open end28, housing20is provided with a plurality (with only one being shown inFIG. 5) of equi-angularly spaced and longitudinally extended tapered inner angled friction surfaces36. Each tapered inner angled friction surfaces36on housing20converges toward the longitudinal axis22and toward the closed end26of the draft gear housing20. Preferably, housing20is provided with three equally spaced longitudinally extended and tapered inner angled friction surfaces36but more tapered surfaces could be provided without detracting or departing from the spirit and novel concept of this invention disclosure.

In the embodiment shown inFIG. 3, draft gear assembly10is also provided with a friction clutch assembly40for dissipating forces or impacts axially directed against the draft gear assembly10as a result of a coupling operation or normal operation of the railcar16(FIG. 1). In the embodiment shown inFIGS. 3 and 4, the friction clutch assembly40includes a plurality of friction members or shoes42radially arranged about axis22and in operable combination with the open end28of the draft gear housing20. As shown by way of example inFIG. 3, the friction clutch assembly40can be provided with three equi-angularly spaced friction members42but more friction members could be provided without detracting or departing from the spirit and novel concept of this invention disclosure. Suffice it to say, in the embodiment shown by way of example inFIGS. 3 and 4, the number of friction members42forming part of the friction clutch assembly40are equal in number to the number of tapered inner angled friction surfaces36on housing20.

In the embodiment shown by way of example inFIG. 5, each friction member42has axially or longitudinally spaced first and second end44and44′, respectively. Moreover, each friction member42has an outer or external tapered sliding surface46. As will be appreciated by those skilled in the art, each inner angled friction surface36on housing20combines with each outer tapered sliding surface46on each friction member42to define a first angled friction sliding surface48therebetween. The first friction sliding surface48is disposed at an angle θ relative to the longitudinal axis22of the draft gear assembly10. Preferably, the angle θ of the first friction sliding surface48ranges between about 1.5 degrees and about 5 degrees relative to the longitudinal axis22of the draft gear assembly10. In a preferred embodiment, the angle θ of the first friction sliding surface48ranges between about 1.7 degrees and about 2 degrees relative to the longitudinal axis22of the draft gear assembly10.

In the illustrated embodiment, the friction clutch assembly40further includes a wedge member or actuator50arranged for axial movement relative to the open end28of housing20. As shown inFIGS. 1, 4 and 5, an outer end52of the wedge member50preferably has a generally flat face extending beyond the open end28of housing20for a distance measuring about 4.5 inches and is adapted to press or bear against a conventional follower53such that impact forces directed against to an against the actuator50are axially applied to the draft gear assembly10during operation of the railcar16(FIG. 1). As known, wedge member50is arranged in operable combination with the friction members42.

In the embodiment illustrated by way of example inFIG. 5, wedge member or actuator50defines a plurality of outer tapered or angled friction surfaces57arranged in operable combination with the friction members42of the clutch assembly40. Although only one friction surface57illustrated inFIG. 5, the number of friction surfaces57on the wedge member50equals the number of friction surfaces on members42forming part of the clutch assembly40.

In the embodiment illustrated by way of example inFIG. 5, each outer angled friction surface57on wedge member50combines with an inner angled sliding surface47on each friction member42to define a second angled friction sliding surface58therebetween. The second friction sliding surface58is disposed at an angle β relative to the longitudinal axis22of the draft gear assembly10. Preferably, the angle β of the second friction sliding surface58of friction clutch assembly40ranges between about 32 degrees and about 45 degrees relative to the longitudinal axis22of the draft gear assembly10.

Wedge member50is formed from any suitable metallic material. In a preferred form, and as shown inFIGS. 3, 4 and 5, the wedge member or actuator50defines a generally centralized longitudinally extending bore54.

As shown inFIGS. 3, 4 and 5, toward the open end28, housing20is provided with a series of radially inturned stop lugs23which are equi-angularly spaced circumferentially relative to each other. Toward a read end thereof, wedge member50includes a series of radially outwardly projecting lugs53which are equi-angularly disposed relative to each other and extend between adjacent friction members42so as to operably engage in back of the lugs23on housing20and facilitate assembly of the draft gear assembly10.

As shown inFIG. 5, draft gear assembly10furthermore includes a spring seat or follower60arranged within the hollow chamber34of housing20and disposed generally normal or generally perpendicular to the longitudinal axis22of the draft gear assembly10. Spring seat60is adapted for reciprocatory longitudinal or axial movements within the chamber34of housing20and has a first surface62in operable association with the second or rear end44′ of each friction member42. As shown inFIG. 4, spring seat60also has a second or spring contacting surface64.

An axially elongated elastomeric spring assembly70is generally centered and slidable within chamber34of the draft gear housing20and forms a resilient column for storing, dissipating and returning energy imparted or applied to the free end52of wedge member50during axial compression of the draft gear assembly10. One end of spring assembly70is arranged in contacting relation with the end wall24of housing20. A second end of spring assembly70is pressed or urged against surface64of the spring seat60to oppose inward movements of the friction members42and wedge member50in response to impact forces being directed to and/or against the draft gear assembly10.

Spring assembly70is precompressed during assembly of the draft gear assembly10and serves to: 1) maintain the components of the friction clutch assembly40, including friction members42and wedge member50in operable combination relative to each other and within the draft gear housing20both during operation of the draft gear assembly10as well as during periods of non-operation of the draft gear assembly10; 2) maintain the free end52of wedge member50pressed against the follower53(FIG. 1); and, 3) maintain the follower53and the draft gear housing20pressed against stops15and17on the centersill14(FIG. 1), respectively. In the illustrated embodiment, spring assembly70, in combination with the friction clutch assembly40, is capable of absorbing and dissipating impacts or energy directed axially thereto up to about 900,000 lbs.

In the form shown inFIG. 4, spring assembly70is configured with a plurality of individual units or springs72arranged in axially stacked adjacent relationship relative to each other. In the form shown inFIG. 4, the spring assembly70is comprised of five springs72with a rigid separator plate73being disposed between two axially adjacent springs72in the stack of the springs. It will be appreciated that more than five springs72can be arranged in axially stacked relationship relative to each other without seriously detracting or departing from the novel nature and true scope of this invention disclosure.

As described in further detail below, the purpose of the separator plate73between the springs72is to provide the springs72with different dynamic elastic absorption characteristics on opposite sides of the separator plate73so as to optimize dynamic lost work opportunities during an impact event of the draft gear assembly10. To effect such desirous ends, the separator plate73is extremely rigid and is preferably formed from steel or the like.

As shown inFIG. 4, plate73has upper and lower generally planar and generally parallel spring engaging surfaces75and76, respectively. In one form, a distance of about 0.375 inches to about 0.5 inches separates the spring engaging surfaces75and76on plate73. The separator plate73preferably has a generally rectangular configuration which allows it to freely move within the chamber34in the same direction as do the springs72in response to an axial load being placed on the spring assembly70.

In a preferred embodiment, the springs72disposed between the lower surface76of plate73and the end wall24of housing20combine with each other to offer a greater resistance to compression than do the combination of springs72disposed between the upper spring engaging surface75of plate73and the spring engaging surface64of spring seat60.

Each cushioning unit or spring72includes an elastomeric pad78. Preferably, each spring72has a configuration which complements the configuration, in plan, of the housing chamber34. In a preferred form, each spring72has a generally rectangular shape, in plan, and is sized to optimize the rectangular area of the hollow chamber34wherein spring assembly70is slidably centered for axial endwise movements in response to loads or impacts being exerted axially against the draft gear assembly10. Preferably, the pad78of each elastomeric spring72has two spaced and generally planar surfaces74and77. As shown inFIG. 4, the planar surface74of the pad78of the uppermost spring72in the stack of springs72is pressed against the spring contacting surface64of spring seat70. As further shown inFIG. 4, and with the exception of the pads78arranged adjacent to plate73, the lower planar surface77on the pad78of any two axially adjacent springs72abuts with and is pressed against the planar surface74of an axially adjacent spring72. Moreover, the planar surface77of the pad78on the lowermost spring in the stack of springs72is pressed against the end wall24of housing20.

Preferably, the elastomeric pad78and thereby each spring72, comprising spring assembly70is configured such that its radial expansion, in response to impacts or loads being placed thereon, is limited by the walls of housing20thereby enhancing the absorption capabilities of spring assembly70. Turning again toFIG. 2, each spring pad78is preferably configured such that the radial or outward expansion of the pad78will be limited by the housing walls32,32′ before the pad78expands to engage housing walls30,30′. In a preferred embodiment, and during operation of the draft gear assembly10, and especially those pads78of springs72disposed closer to the spring seat60, will radially expand in response to an impact load being placed thereon, to such an extend as they positively engage and/or contact against the inner surface of the housing walls32and32′ whereby enhancing the absorption capabilities of those springs72of the spring assembly70disposed closest to the spring seat60. In one form of this invention disclosure, the springs72are maintained in general axial alignment with each other and relative to the longitudinal axis22during operation of the draft gear assembly10by an elongated guide rod79(FIG. 2) which, in one form, preferably extends substantially the entire length of the spring assembly70.

Preferably, each elastomeric pad78is formed from a polyester material having a Shore D durometer hardness ranging between about 40 and 60 and an elastic strain to plastic strain ratio of about 1.5 to 1. The working process and methodology for creating the each spring unit72involves creating a preform block which is precompressed to greater than 30% of the preformed height of the preform thereby transmuting the preform into an elastomeric spring.

In one embodiment of the present invention disclosure, the durometer hardness of those elastomeric springs comprising spring assembly70may be different relative to each other. That is, the cumulative durometer hardness of the springs72disposed between spring seat60and plate73can be different from the cumulative durometer hardness of the springs72disposed between housing end wall24and plate73. As mentioned, however, it is preferable for the cumulative durometer hardness of the springs72between the housing end wall24and plate73to be greater or harder than the cumulative durometer hardness of the springs72between spring seat60and plate73. Such a design allows the functionality and performance characteristics of the of the draft gear assembly10to be “fine tuned” to the particular environment wherein the draft gear assembly10is to be used and function.

As shown inFIGS. 1, 2 and 4, a relatively large rectangular opening80is preferably formed in wall30of the draft gear housing20. Opening80is sized such that one or more of the spring units72and plate73can be inserted through the opening80in a direction extending generally normal to the longitudinal axis22of the draft gear assembly10and into the hollow chamber34of housing20. Housing wall30′ may also be provided with an opening82. Preferably, the peripheral margin84of opening82defines a smaller area than the margin83of opening80.

As mentioned above, the purpose of the rigid separator plate73between the springs72is to provide the springs72with different dynamic elastic absorption characteristics on opposite sides of the separator plate73so as to optimize dynamic lost work opportunities during an impact event of the draft gear assembly10.FIG. 6is a schematic graphical representation of the forces realized by a conventional friction/elastomeric draft gear assembly. Whereas,FIG. 7is a schematic graphical representation of the forces realized by a draft gear assembly embodying a spring assembly70as described above and configured with a separator plate73between the opposed ends thereof. A comparison betweenFIGS. 6 and 7quickly and readily reveals how the spring assembly70configured with plate73disposed between opposed ends of the spring assembly70optimizes the dynamic lost work opportunities during an impact event of the draft gear assembly10.

As used herein and throughout, the phrase “lost work opportunity” means and refers to where the force levels imparted to the draft gear assembly drop-off or fall off dramatically over a given travel. The areas shown in dash lines inFIG. 6between points A-B and C-D represent lost work opportunities for a conventional draft gear assembly.FIG. 7schematically represents the force levels for a given travel of a draft gear assembly embodying principals and teachings of the present invention disclosure. The points A, B, C, D and E inFIG. 7are similar to the force levels for a given travel schematically represented at points A, B, C, D and E inFIG. 6. The force levels for a given travel shown inFIG. 6as compared to the force levels for a given travel shown inFIG. 7shows how the a draft gear assembly embodying those features and teachings of the present invention disclosure optimizes the lost work opportunities during an impact event on the draft gear assembly10. In the embodiment shown by way of example inFIG. 7, the distance between points D and E schematically represent additional work opportunities provided by a draft gear assembly embodying the teachings and principals of this invention disclosure.

FIG. 8schematically represents the performance of a draft gear assembly10embodying the principals and teachings of this invention disclosure, with the spring assembly70being configured to function in combination with the angles θ and β of the first and second friction sliding surfaces48and58, respectively, relative to the longitudinal axis22the draft gear assembly10. As shown inFIG. 8, such a draft gear10consistently and repeatedly withstands between about 70,000 ft-lbs. and about 85,000 ft-lbs. of energy imparted thereto at a force level not exceeding 600,000 lbs. over a range of travel of the wedge member50in an inward axial or longitudinal direction relative to the draft gear housing20approximating 3.9 inches.

Alternatively,FIG. 9schematically shows performance of a draft gear10with the spring assembly70of the draft gear assembly10being configured to function in operable combination with the angles θ and β of the first and second friction sliding surfaces48and58, respectively, relative to the longitudinal axis22. As shown, the draft gear assembly10consistently and repeatedly withstands about 110,000 ft-lbs. of energy of energy imparted thereto at a force level not exceeding 900,000 lbs. over a range of travel of the wedge member50in an inward axial direction relative to the draft gear housing20not exceeding 4.5 inches

Suffice it to say,FIG. 9also schematically shows performance of a draft gear10with the spring assembly70being configured to function in operable combination with the angles θ and β of the first and second friction sliding surfaces48and58, respectively, relative to the longitudinal axis22the draft gear assembly10. As shown, the draft gear assembly10consistently and repeatedly withstands between about 70,000 ft-lbs energy to about 110,000 ft-lbs of energy imparted thereto while not exceeding a force level of about 900,000 lbs. over a range of travel of the wedge member50in an inward axial direction relative to the draft gear housing20not exceeding 4.5 inches.

With the present invention disclosure, and with no design changes to the centersill14on railcar16, the draft gear assembly10is configured such that the wedge member50can achieve a range of longitudinal or horizontal movement in one axial direction of about 4.5 inches. That is, the draft gear assembly10of this invention disclosure permits 4.5 inches of travel in a “buff” direction and 4.5 inches of travel in a “draft” direction. This advantageous gain in longitudinal movement of the wedge member50allows the draft gear assembly10to consistently and repeatedly withstand between about 70,000 ft-lbs and about 110,000 ft-lbs of energy imparted thereto while not exceeding a force level of about 900,000 lbs. over a range of travel of the wedge member50in an inward axial direction relative to the draft gear housing20not exceeding 4.5 inches.

From the foregoing, it will be observed that numerous modifications and variations can be made and effected without departing or detracting from the true spirit and novel concept of this invention disclosure. Moreover, it will be appreciated, the present disclosure is intended to set forth exemplifications which are not intended to limit the disclosure to the specific embodiments illustrated. Rather, this disclosure is intended to cover by the appended claims all such modifications and variations as fall within the spirit and scope of the claims.