View source for Tightlock coupling

{{Short description|Type of railcar coupler}}

{{train topics}}
[[File:Cab car 8312 at Hayward station, July 2018.JPG|thumb|Type H Tightlock couplers on a [[California Car (railcar)|California Car]] [[Control car|cab car]] with separate [[Railway air brake|air brake]] and [[head end power]] connections|left]]
Type H '''Tightlock''' couplers are a variety of [[Janney coupler]], typically used on [[North American]] mainline [[Passenger car (rail)|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 line]]s for the [[Railway air brake|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 {{convert|33|in|mm|0}}, with a {{convert|34+1/2|±|1|in|mm|0}} maximum height on empty cars and {{convert|31+1/2|±|1|in|mm|0}} minimum height on loaded cars.<ref>AAR Manual of Standards and Recommended Practices, Section S, Part I:Casting Details, Issue 06/2007</ref>

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== AAR Type F ==
{{Expand section|date= December 2021}}<!-- Copy text from [[Janney coupler#Changes since 1873]] -->
AAR Type F '''Vertical InterLock''' couplers,<ref>[http://www.mcconway.com/rail_prod/f_coupler/f_coup_bod.htm Type F coupler]</ref> often mistaken for the Type H '''Tightlock''', are another variety, typical on North American [[Gondola (rail)#"Bathtub" gondolas|gondola wagons]] that go through [[rotary car dumper|rotary dumpers]].
<gallery class="center">
File:AAR Type F coupler a.jpg|Type F Interlock couplers
File:AAR Type F coupler b.jpg|Type F Interlock couplers
</gallery>
{{clear}}

==Tightlock use in the United Kingdom==
[[File:Northern-321901-coupling-01.jpg|thumb|Type H Tightlock couplers on a [[British Rail Class 321]] EMU with integral air brake and head end power connections]]
Type H couplers are in widespread use on [[multiple units|multiple unit]] passenger trains in the UK built from the mid 1970s onwards. The previous generation of [[Slam door trains|slam door units]] fitted with [[Janney coupler|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. [[British Rail Class 313|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:
{{div col|colwidth=23em}}
* [[British Rail Class 313|Class 313]]
* [[British Rail Class 314|Class 314]]
* [[British Rail Class 315|Class 315]]
* [[British Rail Class 317|Class 317]]
* [[British Rail Class 318|Class 318]]
* [[British Rail Class 319|Class 319]]
* [[British Rail Class 320|Class 320]]
* [[British Rail Class 321|Class 321]]
* [[British Rail Class 322|Class 322]]
* [[British Rail Class 323|Class 323]]
* [[British Rail Class 365|Class 365]]
* [[British Rail Class 357|Class 357]]
* [[British Rail Class 465|Class 465]]
* [[British Rail Class 466|Class 466]]
* [[British Rail Class 507|Class 507]] 
* [[British Rail Class 508|Class 508]]
{{div col end}}

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,<ref>[http://news.bbc.co.uk/1/hi/uk/422125.stm Connex blames its drivers as trains come apart] ''[[BBC News]]'' 16 August 1999</ref> 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]] [[British Rail Class 375|Class 375s]] had been built with Tightlock couplers for [[Connex South Central]] and [[Connex South Eastern]], but it was quickly decided that [[Dellner coupling]]s 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==
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* [[Janney coupler#Changes since 1873|Changes to the Janney coupler since 1873]]
* [[Draft gear]]
* [[Drawbar (haulage)|Drawbar]]
* [[Gangway connection]]
* [[Jane's World Railways]], lists the coupler(s) used on any railway system
* [[Headstock (rolling stock)#Length over headstocks|Length over headstocks]]
* [[Railway coupling#Multi-function couplers|Multi-function couplers]]
* [[Railway coupling]]
* [[Railway coupling by country]]
* [[Rotary car dumper]]
* [[Tank car#Safety|Safety of tank cars]]
* [[Slack action]]
* [[Three-point hitch]]
{{div col end}}

== References ==
<references/>

==External links==
* [https://web.archive.org/web/20190108100622/https://books.google.com/books?id=bz0OBGxRjjcC&pg=PA573&dq=%2B%22tightlock+coupler%22+%2B%22first+tried+in+1928%22+%2B%22New+York+Central%22&hl=en&sa=X&ved=0ahUKEwj2r-uk6dveAhVtp4MKHbsoAskQ6AEIKDAA#v=onepage&q=%2B%22tightlock%20coupler%22%20%2B%22first%20tried%20in%201928%22%20%2B%22New%20York%20Central%22&f=true TypeH TightLock Coupler Developed And First Used 1928 In North America On New York Central RR]
* [http://www.google.ca/search?ei=KLXyW5C_J-fjjwT41LdI&q=%2B%22APTA-PR-M-RP%22+%2B%22tightlock%22&oq=%2B%22APTA-PR-M-RP%22+%2B%22tightlock%22&gs_l=psy-ab.3...63562.66317..69197...0.0..0.118.201.1j1......0....1j2..gws-wiz.......0i71.A1Ptrw6oKFA TypeH TightLock Coupler Made AAR APT Standard In 1947 For Passenger Stock]
* [http://trn.trains.com/en/Railroad%20Reference/ABCs%20of%20Railroading/2006/05/Couplers.aspx ''Trains Magazine'' Article]
* [https://patents.google.com/patent/US4102459 Coupler Adapter]: Janney To [[SA3 coupler]]

{{Railway coupling}}

{{DEFAULTSORT:Tightlock Coupling}}
[[Category:Couplers]]
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