Knuckle couplers are a semi-automatic form of railway coupling that allow rail cars and locomotives to be securely linked together without rail workers having to get between the vehicles.
Originally known as Janney couplers (the original patent name) they are almost always referred to as Knuckles in the US and Canada (regardless of their actual official model name, nowadays generally various AAR types in North America), but are also known as American, AAR, APT, ARA, MCB, Buckeye, tightlock (in the UK) or Centre Buffer Couplers.
There are many variations of knuckle coupler in use today, and even more from the past, some variants of knuckle include:
Janney: the American original, a rather finicky coupler; reportedly annoying to make open and close.
Castle: an improvement on the Janney design, and a step towards the modern knuckle.
Split Knuckle: a rarer type, which replaces the finger of the Knuckle (the little flap that actually links two knuckles together, one of the few moving parts) with one that has a cut out in the middle of it and a hole bored through it; this modification was designed to work with the older Link and Pin couplers in widespread use before, though could reasonably work with European style chain couplers too.
AAR: AAR, the modern American knuckle, they have several variants of their own; ranging from the standard knuckle, to long drawbar ones, to passenger models, to a type designed specifically for tank cars.
Janney couplers were first patented in 1873 by Eli H. Janney (U.S. patent 138,405).[2][3] Andrew Jackson Beard was amongst various inventors that made a multitude of improvements to the knuckle coupler;[1] Beard's patents were U.S. patent 594,059 granted 23 November 1897, which then sold for approximately $50,000, and U.S. patent 624,901 granted 16 May 1899.
In the UK, several versions of Janney couplers are fitted to a limited number of coaches, multiple units, wagons and locomotives.
Janney Type E, Type F Interlock, and Type H tightlock couplings are compatible subtypes, each intended for specific rail car types.
Prior to the formation of the Association of American Railroads (AAR) these were known as Master Car Builder (MCB) couplers.[4] In 1934, the MCB was renamed as the AAR.
Knuckle couplers of the 1880s and 1890s had a chaotic mixture of proprietary internal components, but all had the standard MCB external contour, making them compatible. There was a multitude of makes and models — Burns, Climax, Gould, Miller, Sharon and Tower. Some worked better than others.
In 1913, American Steel Foundries (ASF) developed the Janney "Type D" coupler, that was then made the MCB standard coupler for North America; new and rebuilt rolling stock had to be fitted with that coupler. That ended the market for knuckle couplers with proprietary components, excepting those exported from the US to other countries not complying with MCB standards.
The Alliance coupler, named after the ASF-owned foundry in Alliance, Ohio, was developed as a lighter build than the "Type D", and was marketed by the Amsted Corporation, parent of ASF, as the "Standard for the World". It is still the most-used knuckle coupler in the world. The modern Alliance coupler still uses the modern AAR-10 or 10A contour, but has a shorter thus weaker head length, and thus cannot be used on North American interchanged rolling stock.
Manufacturers of modern "Type E", "Type F Interlock" and "Type H Tightlock" couplers include McConway & Torley,[5][6] ASF, and Buckeye, also known as Columbus Castings.
The external contour of Janney knuckle couplers was the first aspect to be standardized by the MCB in the 1880s. Prior to this, there was a chaotic variety of constantly evolving and proprietary external contours and internal components. In 1893, manufacturers standardized on the MCB-5 or Type C contour, then in 1915 on the improved MCB-10 or Type D contour, and again in 1932 on the AAR-10A or Type E contour. The 1893, 1915, and 1932 contours are measurably different with slight dimensional changes that improved performance, yet remain compatible. Janney couplers still use the 1932 contour, though tolerances, metallurgy and machining techniques have improved, resulting in notable reductions in coupler slack. Type H tightlock couplings used on passenger stock have a variation of the 10A contour that nearly eliminates slack during normal operation and minimizes the possibility of "telescoping" during a derailment.
The purpose of couplers is to join rail cars and locomotives to each other so they all are securely linked together. Major Eli Janney, a Confederate veteran of the American Civil War, invented the semi-automatic knuckle coupler in 1868. It automatically locks the couplers on cars or locomotives together without a rail worker having to get between the cars, and replaced the link and pin coupler, which was a major cause of railroad worker injuries and deaths. The locking pin that ensures Janney couplers remain fastened together is withdrawn manually by a worker using the "cut lever", which is operated from either side of the railroad car and does not require the person to go between the cars. The only time the worker has to go between cars is after they have been securely coupled, to hook up the air lines for the pneumatic brakes, and the head-end power cables in the case of passenger cars.
Modern Janney couplers typically mount to rail cars and locomotives via draw gear; early Janney couplers often had transitional shanks which mounted into legacy link and pin coupler pockets, or bolted directly to steam locomotive headstocks.
Knuckle couplers are used in the Americas, Africa, Asia-Pacific, UK, Belgium and Spain (narrow gauge railway only).
Among its features:
Janney Type E double-shelf couplers are yet another variety, typical on North American hazardous material tank cars. [13][14][15] The Janney coupler is commonly used on railway couplings, as it is strong and locks automatically. Janney coupler was patented by Eli Janney after the US Civil War. The Janney interlocking coupling system is much safer than the links before it. Janney coupler is like two curved human hand.[16][17]
With gooseneck couplers or offset shank couplers, the horizontal centerline of the coupler head is above the horizontal centerline of the coupler shank, or shaft, and the draw gear. This arrangement is designed for use with low-floor freight cars, to lift the coupler head high enough to match the couplers on other rolling stock.[18] The large bogie boxvans for car parts, used on the Victorian Railways, were fitted with gooseneck couplers for that reason.
The Henricot coupler, a variation on the Janney coupler, was introduced by Belgian engineer and entrepreneur Émile Henricot of Court-Saint-Étienne. It is used on certain electric multiple units of the Belgian State Railways, including the NMBS/SNCB class 75.
Janney was a dry goods clerk and former Confederate Army officer from Alexandria, Virginia, who used his lunch hours to whittle from wood an alternative to the link and pin coupler. The term Buckeye comes from the nickname of the US state of Ohio, the "Buckeye state" and the Ohio Brass Company[19] which originally marketed the coupling.[12][20]
In 1893, satisfied that an automatic coupler could meet the demands of commercial railroad operations and, at the same time, be manipulated safely, the US Congress passed the Safety Appliance Act. Its success in promoting switch-yard safety was stunning. Between 1877 and 1887, approximately 38% of all railworker 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 11,710 in 1893 to 2,256 in 1902, even though the number of railroad employees steadily increased during that decade.[21]
When the Janney coupling was chosen to be the American standard, there were 8,000 patented alternatives to choose from. The only significant disadvantage of using the AAR (Janney) design is that sometimes the drawheads need to be manually aligned.
During the transition period from link-and-pin couplers, knuckle couplers on many locomotives had a horizontal gap and a vertical hole in the knuckle itself to accommodate, respectively, a link and a pin, to enable it to couple to vehicles which were still equipped with the older link-and-pin couplers.
