1. Field of the Invention
The present invention relates to railroad couplings, and more particularly to a railroad coupler knuckle having external weight reducing features and a method of forming the same.
2. Background Information
A railroad coupling (or a coupler) is a device for connecting rolling stock, i.e. the railcars, in a train. The design of the coupler is standard, and is almost as important as the track gauge, since flexibility and convenience are maximized if all rolling stock can be easily and quickly coupled together. The equipment that connects the couplings to the rolling stock is known as the draft gear.
The Janney Coupler is a semi-automatic railway knuckle coupler. The earliest commercially successful version of the semi-automatic Knuckle Coupler was patented by Eli H. Janney in 1873 bearing U.S. Pat. No. 138,405 which is incorporated herein by reference. Mr. Janney, a major in the Confederate Army during the American Civil War and serving on Gen. Robert E. Lee's staff, was a dry goods clerk post war in Alexandria Va., home of the modern day United States Patent and Trademark Office, where he developed his knuckle coupler. The City of Alexandria named one of their streets in his honor, Janney's Lane.
In 1893, satisfied that a semi-automatic knuckle coupler could meet the demands of commercial railroad operations and, at the same time, be manipulated safely, the United States Congress passed the Safety Appliance Act (SAA). Its success in promoting switchyard safety was stunning. Between 1877 and 1887, approximately 38% of all rail worker accidents involved coupling. That percentage fell as the railroads began to replace link and pin couplers with automatic couplers. By 1902, only two years after the SAA's effective date, coupling accidents constituted only 4% of all employee accidents. Coupler-related accidents dropped from nearly 11,000 in 1892 to just over 2,000 in 1902, even though the number of railroad employees steadily increased during that decade. Thus the semi-automatic knuckle coupler has played a critical role in improving railway safety for workers.
In the United Kingdom, where the semi-automatic knuckle coupler is fitted to some rolling stock, mostly for passenger trains, it is also known as a “Buckeye Coupler”, possibly originating from the coupler's manufacture as early as 1890 by the Buckeye Steel Castings firm in Columbus, Ohio. The AAR/APTA Type E, Type F, and Type H tightlock couplers are all compatible semi-automatic Knuckle couplers, but are employed on specific types rail cars (general freight, tank cars, rotary hoppers, passenger, etc.).
Prior to the formation of the AAR (Association of American Railroads) these types of couplers were known as MCB Couplers (Master Car Builders Association). After 1910 the MCB reconstituted itself into the AAR. In 1913 the American Steel Foundries (ASF) had developed the new Type “D” coupler that was accepted as the standard coupler for the USA, and no new equipment could be built using any other coupler. This standard design ended the market for couplers with a proprietary head design, which were common in the MCB days, to all but those exported from the USA to other countries not governed by the AAR standards. The Interlocking contour of knuckle couplers was the first aspect to be standardized. In the MCB years, prior to about 1910, there were many proprietary “head” designs, and many MCB standard contours, which were constantly evolving and changing (as the approved standard contour for new couplers) every few years.
In about 1910 the producers were all using the then standardized MCB-10 contour, soon to become the AAR-10. In 1930 the AAR Type “D” was improved and became the Type “E”; the contour, however, stayed the same. A few years later the 10 contour was modified into a then optional standard called the 10A contour.
The most modern contour, for a plain Type “E” knuckle coupler, is still the AAR-10 and 10A, which are largely indistinguishable from the 1910 era MCB-10 contour. The same MCB-10 contour has been an approved standard for interchange service for over 100 years, with only the slightest dimensional changes. The Type “H” or “tight-lock” couplers, which are used on passenger-carrying rolling stock, also use slight revisions to the old 10A contour. Type H coupler, also called a “tight-lock” variation, is intended to reduce slack action and improve safety for passenger cars is now under the supervision of the APTA (American Public Transportation Association).
The conventional knuckle currently available is a cast knuckle that includes cored sections, such as disclosed in U.S. Pat. No. 4,605,133. The front core of a knuckle is commonly referred to as the finger core. The finger core is commonly constructed to produce an internal cavity having thin ribs. These ribs made out of the standard grade E cast steel have demonstrated a weakness to the load environment with the development of fatigue and/or hot tear cracks. The fatigue cracks can grow over time and eventually lead to knuckle failure which results in separation of railcars. Separately, internal or external cracks in the knuckle are a cause for replacement of the knuckle. The rear core of a knuckle is commonly referred to as the kidney core. Knuckles can sometimes break within this portion of the knuckle and this has proven to be a very undesirable location for a failure. A failure in this region of the knuckle can lead to knuckle jamming within the coupler body and prevent a change out of a failed knuckle, thereby requiring the entire coupler assembly to be replaced, a very costly repair.
U.S. Pat. No. 5,954,212 discloses a lightweight knuckle for use in an AAR Standard E or F type railroad car couplers. The outer contouring and inner voids of the knuckle are radically changed from an existing AAR Standard knuckle. The nose of the knuckle is provided with a pair of parallel, coplanar flat surfaces between which is a projection which extend outwardly from the flat surfaces and terminates at an outer curved surface which has the same curvature as the corresponding curvature of the existing AAR Standard knuckle. U.S. Pat. No. 6,129,227 discloses a similar lightweight knuckle.
U.S. Pat. No. 8,302,790 discloses a railway coupler knuckle which has a cavity formed inside the tail portion and at least a portion of the transition portion and a first wall extends between surfaces of the cavity adjacent the transition portion.
U.S. Patent Application Publication 2012-0217217 discloses a cast coupler knuckle formed with internal cavities without using a conventional finger core. See also U.S. Pat. Nos. 8,662,327, 8,646,631, 8,631,952, 8,499,819, 8,485,371.
U.S. Pat. Nos. 8,297,455 and 8,381,923 disclose a knuckle for a railway coupler system made without internal voids or cores. Instead, external circular or disc shaped pockets are formed on the front face and tail portion surface to reduce weight. The knuckle is formed by investment casting (a process based upon lost-wax casting).
U.S. Pat. No. 9,038,836 discloses a lightweight, coupler which is constructed from cast austempered ductile iron.
U.S. Pat. No. 9,199,652 discloses a lightweight, fatigue resistant knuckle utilizing improved internal coring and/or rib arrangements using an austempered metal, such as, for example, austempered ductile iron, austempered steel, as well as other austempered metals and austempered metal alloys.
The above identified patents and publications are incorporated herein by reference. There remains a need in the art for railroad coupler knuckles that reduce weight, improve manufacturability and improve fatigue life.