The present invention relates to rail car coupler knuckles and, more specifically, to an internal supporting structure for coupler knuckle pivot pins.
Couplers are used to join rail cars and locomotives to each other so that they all securely linked together. The Association of American Railroads (AAR) standard coupler uses a knuckle that is pivotally mounted in the coupler by a pivot pin to engage and disengage from another coupler. Due to the forces involved in coupling and during transit, pivot pins experience significant loading and can bend and eventually break, thereby resulting in a failure of the pivot pin and coupler assembly. Depending on the geometry of the other parts of the coupler assembly, the load through the pivot pin may be increased and the bending more pronounced. As the load is increased, the fatigue life of the pivot pin can be dramatically reduced, thereby leading to premature failure of the pivot pin. Pin failure is evident when the knuckle is opened to uncouple a railcar, and the damaged pin allows the knuckle to fall out of the coupler body. Repairing this condition is particularly dangerous as repair personnel must work between the rail cars on an operating track, which presents a number of significant safety concerns. In some cases, pivot pin failure results in the pin becoming deformed along the portion that extends through the knuckle, which can result in the pivot pin being stuck inside the knuckle. In this situation, it may not even be possible to uncouple the railcar with the broken pin from another rail car, and to correct requires that repair personnel work between the cars of an operating track.
Conventional knuckle designs connect to the pin at two locations. The first location is approximately two and one quarter inches below the top of the head, which coincides with the top of the knuckle and coupler. The second location is approximately ten and one quarter inches below the top of the head, which coincides with the the bottom of the knuckle and coupler after the pivot pin has passed through the knuckle. These connection points are not sufficient to prevent bending or failure of the portion of the pivot pin that extends within the knuckle itself. Some attempts to remedy this approach rely on a solid body knuckle with a throughbore that can accept the pivot pin. As a result, any bending of the pivot pin is restrained by the throughbore of the knuckle through which the pivot pin is passed. Solid body designs are significantly heavier than conventional designs, and can be more costly. In addition, the need for any pivot pin repairs necessarily delays operation of the train and can adversely impact other routes. As a result, there is a need in the art for an approach that can reduce the stress on the pin within the boundaries of the knuckle without having to employ a solid body structure.
The present invention reduces the stress on the pivot pin of coupler by providing additional support for the pivot pin along the portion of the pivot pin that extends within the knuckle. More specifically, the knuckle of a coupler according to the present invention includes a support positioned along the portion of the pivot pin that extends through the knuckle between the upper and lower contact location. The support is positioned in a location that corresponds approximately to the mid-point of the pivot pin, at an orientation where maximum deflection of the pivot pin occurs during draft loading of the coupler, which is the loading condition that is most likely to result in failure of the pivot pin and knuckle. The present invention thus reduces stress at the most common failure location by limiting the physical amount the pin can bend with a structural feature that is internal of the knuckle and positioned in line with the draft loading direction so that pivot pin is supported against bending. The present invention thus provides a knuckle weight that is comparable to the weight of a standard knuckle and significantly less than a solid body knuckle.
In a first embodiment, the present invention is a knuckle for a rail car coupler having a body having a throughbore defining a first bearing surface at a first end of the throughbore and a second bearing surface and a second end of the throughbore and a support extending into the throughbore and including a third bearing surface that is positioned between the first bearing surface and the second bearing surface. The support may be a post extending from an interior surface of the knuckle into the throughbore. The body may include a series of hollow regions therein. The post may extend from the interior surface of the knuckle in one of the series of hollow regions. The post may be positioned so that the third bearing surface will abut a pivot pin that is inserted into and extends through the throughbore. The post may be positioned so that the third bearing surface will abut an intermediate portion of the pivot pin that extends between the first bearing surface and the third bearing surface. The post may be positioned so that the third bearing surface will abut a central point of pivot pin.
In a further embodiment, the support of the knuckle may be a bridge extending from a first interior surface of the knuckle across the throughbore to a second interior surface of the knuckle to form the third bearing surface between the first interior surface and the second interior surface. The support may be positioned so that the third bearing surface will abut a pivot pin that is inserted into and extends through the throughbore. The support may be positioned so that the third bearing surface will abut an intermediate portion of the pivot pin that extends between the first bearing surface and the third bearing surface. The support may be positioned so that the third bearing surface will abut a central point of pivot pin.
In an additional embodiment, the present invention may have a second support extending into the throughbore and including a fourth bearing surface positioned between the first bearing surface and the second bearing surface. The second support may be positioned so that the fourth bearing surface will abut a pivot pin that is inserted into and extends through the throughbore. The second support may be spaced apart from and extend in parallel to the first support. The first support and the second support may be positioned so that the third bearing surface and the fourth bearing surfaces are on opposing sides of a central point of the pivot pin.
The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which:
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Preferably, support 26 is positioned in the interior of knuckle 14 so that it is located centrally along pivot pin 16 relative to bearing surface 20 and bearing surface 22 and so that it is in alignment with the direction of maximum pin deflection during draft loading of any rail car outfitted with coupler 10. Support 26 may be positioned anywhere along the length of pivot pin 16 that extends between bearing surface 20 and bearing surface 22, but is preferably located centrally within that length. The direction of maximum pin deflection during draft loading is shown in
Knuckle 14 may be manufactured via casting or forging using conventional materials in the same fashion as conventional couplers, and may retrofit into legacy couplers 10 or included with new couplers 10. Knuckle 14 is depicted as an E-type, but it should be recognized by those of skill in the art than the present invention may be implemented in other designs, such as an F-type.
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Filing Document | Filing Date | Country | Kind |
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PCT/US2021/041104 | 7/9/2021 | WO |
Number | Date | Country | |
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63049731 | Jul 2020 | US |