Tightlock coupling

Last updated
Janney Type H Tightlock coupler seen on an Amtrak California cab car Cab car 8312 at Hayward station, July 2018.JPG
Janney Type H Tightlock coupler seen on an Amtrak California cab car

Type H Tightlock couplers are a variety of Janney coupler, typically used on North American mainline passenger rail cars. They are designed with mechanical features which reduce slack in normal operation and prevent telescoping in derailments, yet remain compatible with other Janney types used by North American freight railroads.


Like all Janney couplers, the Tightlock is "semi-automatic" with the couplers on cars or locomotives automatically locking when cars are pushed together. However, most tightlock couplers are not fully automatic, as workers still need to go between cars to hook up the air lines for the pneumatic brakes, and connect cables for head-end power and other communications. Also, to separate cars, a worker needs to use a lever to move the locking pin that keeps the coupler closed.

In Europe, some operators experimented with making fully automatic tightlock couplers by adding integral pneumatic and electric connectors, but these connections experienced reliability issues. Most operators who experimented with fully automatic tightlock couplers have now switched to the more common fully automatic Scharfenberg coupler.

Janney Type H TightLock coupler standards were established by the Association of American Railroads. Management and development of the standard was transferred to the American Public Transportation Association in 1971 when passenger service was nationalized in the United States from most private railway companies to Amtrak.

On a standard-gauge railway, the nominal mounting height for the coupler (rail top to coupler center) is 33 inches (838 mm), with a 34 12 ± 1 inch (876 ± 25 mm) maximum height on empty cars and 31 12 ± 1 inch (800 ± 25 mm) minimum height on loaded cars. [1]

Janney Type F

Janney Type F InterLock couplers, [2] often mistaken for the Type H Tightlock, are another variety, typical on North American gondola wagons that go through rotary dumpers.

Tightlock use in the United Kingdom

Type H couplers are in widespread use on multiple unit passenger trains in the UK built from the mid 1970s onwards. The previous generation of slam door units fitted with Buckeye couplers had required a shunter to get down onto the track and stand between the two units to manually trip the coupler mechanism as well as connect or disconnect the air pipes and electrical jumper leads. In order to reduce staffing costs and cut down station dwell times, British Rail looked to incorporate an automatic coupler mechanism in its new power-door trains. Class 313 units were the first stock to incorporate this. Air-operated Tightlock couplers were chosen, together with underslung electrical connector boxes controlled by a Drum switch, and this allowed drivers to single-handedly attach or split a train without having to leave the cab.

Classes of train equipped included:

The Tightlocks were generally a success in the UK, but there were reliability issues and some notable incidents occurred where trains divided in service. The constant couple-uncouple cycles of heavy London commuter services caused the couplers' mechanisms to wear out faster than expected. Connex South Eastern's Networker fleet was particularly susceptible to this and the company blamed its drivers in the media, [3] then changed its coupling instructions to drivers to include a "push-on, pull off" power test and visual inspection to ensure that the knuckles had engaged fully.

By the early 2000s the first batch of Bombardier Electrostar Class 375s had been built with Tightlock couplers for Connex South Central and Connex South Eastern, but it was quickly decided that Dellner couplings [4] would be preferable. All subsequent units were built with these, and their earlier examples were eventually modified.

All multiple-unit trains built for the UK since then have been equipped with Dellner couplings.

See also

Related Research Articles

Railroad car Vehicle used for carrying cargo or passengers on rail transport system

A railroad car, railcar, railway wagon, railway carriage, railway truck, railwagon, railcarriage or railtruck, also called a train car, train wagon, train carriage or train truck, is a vehicle used for the carrying of cargo or passengers on a rail transport system. Such cars, when coupled together and hauled by one or more locomotives, form a train. Alternatively, some passenger cars are self-propelled in which case they may be either single railcars or make up multiple units.

Armagh rail disaster

The Armagh rail disaster happened on 12 June 1889 near Armagh, Ulster, Ireland, when a crowded Sunday school excursion train had to negotiate a steep incline; the steam locomotive was unable to complete the climb and the train stalled. The train crew decided to divide the train and take forward the front portion, leaving the rear portion on the running line. The rear portion was inadequately braked and ran back down the gradient, colliding with a following train.

Vacuum brake Train braking system

The vacuum brake is a braking system employed on trains and introduced in the mid-1860s. A variant, the automatic vacuum brake system, became almost universal in British train equipment and in countries influenced by British practice. Vacuum brakes also enjoyed a brief period of adoption in the United States, primarily on narrow-gauge railroads. Their limitations caused them to be progressively superseded by compressed air systems starting in the United Kingdom from the 1970s onward. The vacuum brake system is now obsolete; it is not in large-scale usage anywhere in the world, other than in South Africa, largely supplanted by air brakes.

Multiple-unit train control, sometimes abbreviated to multiple-unit or MU, is a method of simultaneously controlling all the traction equipment in a train from a single location—whether it is a multiple unit comprising a number of self-powered passenger cars or a set of locomotives—with only a control signal transmitted to each unit. This contrasts with arrangements where electric motors in different units are connected directly to the power supply switched by a single control mechanism, thus requiring the full traction power to be transmitted through the train.

British Rail Class 377 Fleet of electric multiple units in Britain

The British Rail Class 377 Electrostar is a British dual-voltage electric multiple-unit passenger train (EMU) built by Bombardier Transportation at its Derby Litchurch Lane Works from 2001 to 2014. The Electrostar family is the most numerous type of EMU built in the post-privatisation period of Britain's railways.

Railway coupling Mechanism for connecting rolling stock in a train

A coupling is a mechanism used to connect rolling stock in a train. The design of the coupler is standard, and is almost as important as the track gauge, since flexibility and convenience are maximised if all rolling stock can be coupled together.

Railway brake

A railway brake is a type of brake used on the cars of railway trains to enable deceleration, control acceleration (downhill) or to keep them immobile when parked. While the basic principle is similar to that on road vehicle usage, operational features are more complex because of the need to control multiple linked carriages and to be effective on vehicles left without a prime mover. Clasp brakes are one type of brakes historically used on trains.

British Rail Class 220

The Class 220 Voyager is a class of diesel-electric high-speed multiple-unit passenger trains built in Belgium by Bombardier Transportation in 2000 and 2001.

British Rail Class 171 Diesel multiple-unit train by Bombardier

The British Rail Class 171Turbostar is a type of diesel multiple-unit (DMU) passenger train built by Bombardier Transportation at its Derby Litchurch Lane Works in England, which is identical to the Class 170, except for the replacement of the BSI coupler with a Dellner coupling. This provision was made to allow emergency joining with Class 377 DC third-rail electric units, which Southern runs extensively on most lines. The units work on the southern regions of the British railway system, operating services from London Bridge to Uckfield and from Eastbourne to Ashford International, these routes being unelectrified between Hurst Green Junction and Uckfield and between Ore and Ashford International, respectively.

British electric multiple units

An electric multiple unit (EMU) is an electric train capable of operating in multiple with other EMUs that does not have a separate locomotive, typically passenger trains with accommodation in every vehicle and a driving position at each end. The term can also be used to describe a train such as the Advanced Passenger Train that was a permanent formation with a non-driving power car. As of December 2010 two thirds of the passenger carriages in Britain are formed in EMUs.

Electric multiple unit A multiple unit train consisting of self-propelled carriages, using electricity as the motive power

An electric multiple unit or EMU is a multiple-unit train consisting of self-propelled carriages using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages. An EMU is usually formed of two or more semi-permanently coupled carriages, but electrically powered single-unit railcars are also generally classed as EMUs. The great majority of EMUs are passenger trains, but versions also exist for carrying mail.

Multiple working

On the UK rail network, multiple working is where two or more traction units are coupled together in such a way that they are all under the control of one driver.

Scharfenberg coupler Automatic railway coupling

The Scharfenberg coupler is a commonly used type of fully automatic railway coupling.

SA3 coupler

SA3 couplers are railway rollingstock couplings used primarily in Russia and states influenced by the former Soviet Union, such as Finland and Mongolia.

Railway coupling by country

The railcar couplers or couplings listed, described, and depicted below are used worldwide on legacy and modern railways. Compatible and similar designs are frequently referred to using widely differing make, brand, regional or nick names, which can make describing standard or typical designs confusing. Dimensions and ratings noted in these articles are usually of nominal or typical components and systems, though standards and practices also vary widely with railway, region, and era. Transition between incompatible coupler types may be accomplished using Dual or Compromise couplings or a Barrier wagon.

C-AKv coupler Railway vehicle coupler

The C-AKv is a fully automatic coupler design, also known as the Faiveley Transpact; it is a hybrid compatible with both buffers and chain couplers and Russian SA3 couplers, intended as an option for the long delayed EU transition to center buffer couplers. C-AKv is an abbreviation of Compact Automatische Kupplung vereinfacht in German, translating to Compact Automatic Coupler simplified in English.

Janney coupler

Janney couplers are a semi-automatic design, also known as American, AAR, APT, ARA, MCB, knuckle, or center-buffer couplers, which were first patented in 1873 by Eli H. Janney. Andrew Jackson Beard was amongst various inventors that made a multitude of improvements to the knuckle coupler; 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.

Railway coupling conversion railway upgrade

From time to time, a railway decides that it needs to upgrade its coupling system from one that is proving unsatisfactory, to another that meets future requirements. This can be done gradually, which can create many problems with transitional incompatibilities, or overnight, which requires much planning.


Dellner is a Swedish manufacturer of rail vehicle and other industrial components including couplers, dampers and brakes.

Buffers and chain coupler

Buffers and chain couplers are the de facto UIC standard railway stock coupling used in the EU and UK, and on some surviving colonial railways, such as in South America and India. These couplers are an assembly of several devices: buffers, hooks and links or screws.


  1. AAR Manual of Standards and Recommended Practices, Section S, Part I:Casting Details, Issue 06/2007
  2. Type F coupler
  3. Connex blames its drivers as trains come apart BBC News 16 August 1999
  4. Dellner Couplers AB Automatic and Semi-Permanent Couplers