Tightlock coupling

Last updated

Type H Tightlock couplers are a variety of Janney coupler, typically used on North American mainline passenger rail cars. They have mechanical features that 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". The couplers automatically lock when cars are pushed together, but workers must go between cars to hook up the air lines for the pneumatic brakes and connect cables for head-end power and other communications. To separate cars, a worker must 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 proved unreliable, and most have switched to the more common fully automatic Scharfenberg coupler.

Janney Type H Tightlock coupler standards were established by the Association of American Railroads, which transferred the standard 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]

AAR Type F

AAR Type F Vertical 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/Henricot 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:

Tightlock was 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 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

<span class="mw-page-title-main">Railroad car</span> Vehicle used for carrying cargo or passengers on rail transport system

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 network. 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.

<span class="mw-page-title-main">Multiple-unit train control</span>

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.

<span class="mw-page-title-main">British Rail Class 375</span> British electric multiple unit train that was built by Bombardier Transportation

The British Rail Class 375 Electrostar is an electric multiple unit train that was built by Bombardier Transportation at Derby Litchurch Lane Works, from 1999 to 2005. The class form part of the Electrostar family of units, which also includes classes 357, 376, 377, 378, 379 and 387, the most numerous type of EMU introduced since the privatisation of British Rail.

<span class="mw-page-title-main">Railway coupling</span> Mechanism for connecting rolling stock in a train

A coupling or coupler is a mechanism, typically located at each end of a rail vehicle, that connects them together to form a train. The equipment that connects the couplers to the vehicles is the draft gear or draw gear, which must absorb the stresses of the coupling and the acceleration of the train.

<span class="mw-page-title-main">British Rail Class 220</span> British Diesel-electric multiple unit

The British Rail 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. They were introduced in 2001 to replace the 20-year-old InterCity 125 and almost 40-year-old Class 47-hauled Mark 2 fleets operating on the Cross Country Route. They were initially operated by Virgin CrossCountry and since 2007 have been operated by CrossCountry.

<span class="mw-page-title-main">British Rail Class 466</span> British Electric passenger trains

The British Rail Class 466 Networker are a fleet of 43 electric multiple units that were built by Metro-Cammell in 1993 and 1994. The units are currently operated by Southeastern.

<span class="mw-page-title-main">British electric multiple units</span> British self-powered electric trains

An electric multiple unit (EMU) is an electric self-powered train, capable of operating in multiple with other EMUs and without the need for a locomotive; these are 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 that is a permanent formation with a non-driving power car, such as the Advanced Passenger Train. As of December 2010, two-thirds of the passenger carriages in Great Britain are formed in EMUs.

<span class="mw-page-title-main">British Rail Class 304</span>

The British Rail Class 304 were AC electric multiple units designed and produced at British Rail's (BR) Wolverton Works.

<span class="mw-page-title-main">Control car</span> Unpowered railway or tramway car with a drivers cab

A control car, cab car, control trailer, or driving trailer is a non-powered rail vehicle from which a train can be operated. As dedicated vehicles or regular passenger cars, they have one or two driver compartments with all the controls and gauges required to remotely operate the locomotive, including exterior locomotive equipment such as horns, bells, ploughs, and lights. They also have communications and safety systems such as GSM-R or European Train Control System (ETCS). Control cars enable push-pull operation when located on the end of a train opposite its locomotive by allowing the train to reverse direction at a terminus without moving the locomotive or turning the train around.

<span class="mw-page-title-main">Pioneer III</span>

The Pioneer III railcar was a short/medium-distance coach designed and built by the Budd Company in 1956 with an emphasis on weight savings. A single prototype was built, but declines in rail passenger traffic resulted in a lack of orders so Budd re-designed the concept as an electric multiple unit (m.u.). Six of the EMU coach design were purchased by the Pennsylvania Railroad with the intention of using them as a high-speed self-contained coach that could be used for long-distance commuter or short-distance intercity travel in the Northeast U.S. The 6 production Pioneer III units were the first all-stainless-steel-bodied EMU railcar built in North America and, at 90,000 pounds (41,000 kg), the lightest.

<span class="mw-page-title-main">Scharfenberg coupler</span> Automatic railway coupling

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

Electronically controlled pneumatic brakes are a type of railway braking systems.

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 couplings, a coupling adapter or a barrier wagon.

<span class="mw-page-title-main">C-AKv coupler</span> 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 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. They are also known as American, AAR, APT, ARA, MCB, knuckle, Buckeye, tightlock, Henricot or Centre Buffer Couplers.

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.

<span class="mw-page-title-main">Budd Silverliner</span> American electric multiple unit railcar

The Budd Silverliner was a model of electric multiple unit railcar designed and built by the Budd Company with 59 examples being delivered starting in 1963. Fifty-five of the cars were purchased for the Reading and Pennsylvania Railroads with public funds for use in Philadelphia, Pennsylvania, area commuter rail service with the remaining 4 cars being purchased by USDOT for use in high-speed rail experiments in 1965. Based on a series of 6 prototype Pioneer III cars built in 1958, the Silverliners represented the first production order of "modern" commuter MU equipment purchased by either railroad and earned their name from their unpainted stainless steel construction which contrasted with the painted carbon steel bodies of the pre-war MU fleets. The cars became a fixture of SEPTA Regional Rail service providing the name to their entire series of EMU railcars before finally being retired in 2012 after 49 years in service.

<span class="mw-page-title-main">EMU100 series</span> Former passenger train in Taiwan

The Taiwan Railway EMU100 series was a set of rail cars fabricated by British Rail Engineering Limited and the General Electric Company in 1976 that has operated in Taiwan. The alternating current electric multiple unit (EMU) fleet entered full squadron service in 1979, and was withdrawn from service in 2009. This class of railcars were the first to operate on the electric Tzu-Chiang Express. Due to the unit's British origin, rail buffs have variously nicknamed them "British Girl", "British Lady", or "British Grandma".

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

<span class="mw-page-title-main">Dual coupling</span>

Different types of railroad rolling stock have different couplers depending on the purpose and type of equipment being used and its intended destination. European rolling stock tend to use buffers and chain couplers while American rolling stock uses a Janney coupler or "knuckle coupler". These are incompatible with each other, but where some railroads have obtained older, less expensive used rolling stock from different countries or regions, instead of having to standardize on one form of coupler, it may be useful to be able to use either type of coupler on a piece of rolling stock without having to remove anything.


  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