Janney coupler


Knuckle couplers are a semi-automatic form of railway coupling that allow rail cars and locomotives to be securely linked together without workers having to get between the vehicles.
Originally known as Janney couplers they are almost always referred to as knuckles in the US and Canada, but are also known as American, AAR, APT, ARA, MCB, Buckeye, tightlock, automatic couplers or centre buffer couplers.
There are many variations of knuckle coupler in use today, and even more from the past. Some variants of knuckle couplers include:
Janney: the American original, a rather finicky coupler; reportedly annoying to make open and close. This design was obsolete by 1900.
MCB: In the latter 1880s the Master Car Builder's Association were faced with choosing a standard from the multitude of mutually incompatible automatic coupler designs then on offer. They could not, with any effect, choose a single design, but favored Janney's. The patent holders either proposed, or were persuaded, to release their rights to the Janney coupler's mating profile, and in 1888 a slightly modified profile became the MCB standard. Thus the MCB standard initially specified only the interface between MCB automatic knuckle couplers, leaving all other aspects to open competition between manufactures. There were a number of revisions and additions to the standards over the next two decades, with extensive updates in 1899. By then there were a great many variations of MCB couplers in use - an 1899 Knuckle Identification Chart illustrates 78 mutually incompatible knuckles. Further revisions to the standard followed through 1916, when what is now known as the AAR type D was recommended as the North American standard coupler. However some of the better MCB couplers remained in use for decades, and a few are still manufactured for non-interchange service or export.
The slotted-knuckle variation is a transitional type, used while converting from link-and-pin couplers to knuckle couplers. Here the vertically pivoted knuckle has a horizontal slot through its exposed width, with a vertical pin hole through the knuckle tip. With the knuckle closed and locked, a coupling link can be inserted through the slot and pined through the vertical hole, allowing coupling to cars fitted with the older link-and-pin system. Slotted knuckles were common in North America prior to 1900, in South Africa after 1925, and anywhere else during this conversion. They are rarely found after conversion is complete.
AAR: In the first decade of the 1900s there were upwards of 75 makes of MCB standard-compliant couplers in use on North American railroads. All of these could couple together. Practically none shared internal design or parts. Most were offered with multiple shank patterns to match different draft gears - the Tower coupler had 16. With freight cars freely interchanged throughout the continent's standard-gauge lines, the problem of maintaining these couplers fell upon all roads, and prompt repair of damaged couplers was effectively impossible.
Circa 1913 the MCB Coupler Committee, in cooperation with five of the principal coupler manufactures, set out to devise a standard coupler for North American railroads, one that mated with existing MCB standard couplers, was up to the heaviest anticipated service, and of proven operational efficiency and long service life. The participating coupler companies agreed to each submit their best designs for rigorous testing under the MCB committee's supervision, to work together to eliminate weaknesses and combine the best features of each, and to freely share any patented features chosen or developed for the new standard. The result was the American Association of Railroads Standard "D" Coupler of 1916. This was upgraded to the No. 10 Contour in 1918, which largely eliminated the MCB coupler's tendency to jackknife under buffing forces. A stronger version, the AAR type E was adopted in 1931, the principal change being an increase in knuckle depth from.
Both the D and E were essentially freight car couplers, and necessarily provided a degree of slack in their coupling, which is undesirable in passenger service. The type H Tightlock passenger coupler was developed in the 1930s, made an alternative passenger standard in 1937, and the standard for new North American passenger cars in 1947. This design incorporates a pin and socket that flank what is essentially a type E coupler head. While it can still couple with the freight couplers, two Tightlock couplers, when coupled, form a nearly rigid drawbar between their car's draft gear, eliminating the impact associated with slack action.
The surge in North American freight car capacities in the latter 1900s, particularly that of tank cars, emphasized the need to prevent cars uncoupling in the event of a derailment. Several variations of the standard knuckle coupler incorporate shelves above or below the coupler head, to prevent vertical separation. The development of unit trains for moving coal or ore led to the substitution of rotary dumped gondolas for traditional hopper cars. These incorporate a rotating coupler and draft gear in one end, to allow the cars to be dumped without uncoupling them.

Background

Janney couplers were first patented in 1873 by Eli H. Janney. Andrew Jackson Beard was among various inventors who made many improvements to the knuckle coupler. His U.S. patents were, granted on 23 November 1897 – which he sold for approximately $50,000 – and, granted on 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 types of rail vehicles. Before the Association of American Railroads was formed, they were known as Master Car Builder couplers. 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 developed the Janney "Type D" coupler, which 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 therefore cannot be used on North American interchange rolling stock.
Manufacturers of modern "Type E", "Type F Interlock" and "Type H Tightlock" couplers include McConway & Torley, 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.

Purpose

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 ensures that Janney couplers remain fastened together until 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.

Janney/MCB/ARA/AAR/APTA coupler

Knuckle couplers are used in the Americas, Africa, Asia-Pacific, UK, Belgium and Spain.
Among its features:
  • Maximum tonnage as high as such as on the Fortescue railway line.
  • Minimum ultimate tensile strength:
  • * Grade E knuckles:
  • ** Grade C or Grade E knuckles are required for interchange service.
  • * Grade E coupler bodies:
  • Several knuckle coupler types exist to accommodate various cars, but all are required to have certain common dimensions allowing for compatibility.
  • * Lighter weight railways, notably narrow-gauge lines with no need for interchange, sometimes use smaller versions of the Janney MCB coupler. Such as Victorian narrow gauge lines.
  • Janney couplers are always right-handed, i.e., their shape resembles the human right hand with fingers curled, as viewed from above.
  • Required coupler heights, in North America
  • * Empty cars: ±
  • * Loaded cars: ±
  • Modern AAR standards require knuckle couplers to be bottom-operated on cars and top-operated on locomotives. Operation or uncoupling is accomplished by lifting the release pin with a lever extending to the corner of the car; this pin is locked when the coupler is under tension, so the usual uncoupling steps are to compress the coupling with a locomotive, lift and hold up the pin, then pull the cars apart. "Buckeye" and "SASKop" couplers are side operated variants of knuckle couplers.
  • Trains fitted with knuckle couplers can accommodate heavier loads than any other type of coupler.
  • In North America, knuckle couplers are typical per AAR and APT standards; mainline freight trains often exceed long; in Europe freight trains are typically much shorter, with the legacy buffers and chain coupler remaining the de facto standard.
  • In New Zealand, heavy coal trains were first fitted with knuckle couplers in 1972; a full transition began in 2013 to replace remaining Norwegian couplers with knuckle couplers on freight stock and Scharfenberg couplers on passenger stock.