Slack action

In railroading, slack action is the amount of free movement of one car before it transmits its motion to an adjoining coupled car. This free movement results from the fact that in railroad practice cars are loosely coupled, and the coupling is often combined with a shock-absorbing device, a "draft gear," which, under stress, substantially increases the free movement as the train is started or stopped. Loose coupling is necessary to enable the train to proceed freely around curves and is an aid in starting heavy trains, since the application of the locomotive power to the train operates on each car in the train successively, and the power is thus utilized to start only one car at a time.

Slack action creates a danger of accident, particularly as the length of freight trains get longer. While accidents from slack action do occur in the operation of passenger trains, it does not appear that accidents occurring on passenger trains, whatever their length, are of sufficient severity to cause serious injury or damage.

Modern couplers are designed to reduce slack action over older technology, such as link and pin connections.


*Southern Pacific Co. v. State of Arizona Ex rel. Sullivan, 325 U.S. 761 (1945) []

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • slack|en|ing — «SLAK uh nihng», noun. the action of making or becoming slack; diminution; lessening:»Zinc demand continues strong, with no indications of immediate slackening (Wall Street Journal) …   Useful english dictionary

  • Slack hand — Hand Hand (h[a^]nd), n. [AS. hand, hond; akin to D., G., & Sw. hand, OHG. hant, Dan. haand, Icel. h[ o]nd, Goth. handus, and perh. to Goth. hin[thorn]an to seize (in comp.). Cf. {Hunt}.] 1. That part of the fore limb below the forearm or wrist in …   The Collaborative International Dictionary of English

  • William Y. Slack — Infobox Military Person name= William Y. Slack born= August 1, 1816 died= March 21, 1862 caption= nickname= placeofbirth= Mason County, Kentucky placeofdeath= Moore s Mill, Arkansas allegiance= Confederate States of America branch= branch=… …   Wikipedia

  • spurious class action — One of the former categories of class action in which interests of members of class were several and not interdependent, and where joinder was a matter of efficiency to avoid multiplicity of suits. Slack v. Stiner, C.A.Tex., 358 F.2d 65, 69. This …   Black's law dictionary

  • Coupling (railway) — Knuckle (AAR Type E ) couplers in use ICE coupler A c …   Wikipedia

  • Glossary of rail terminology — Rail transport Operations Track Maintenance High speed Gauge Stations …   Wikipedia

  • Railroad engineer — A railroad engineer, railway engineer, locomotive engineer, train operator, train driver or engine driver is a person who operates a railroad locomotive and train. The engineer is the person in charge of and responsible for the locomotive(s). He… …   Wikipedia

  • Victorian Railways Z vans — Infobox Train background = name = Z van imagesize = 300px caption = Van 611 ZD, in storage at the Seymour Railway Heritage Centre interior interiorcaption = Manufacturer = Victorian Railways Factory = Newport Workshops, others Family = Built =… …   Wikipedia

  • Well car — A double stack car owned by the TTX Company. The 53 ft (16.15 m) capacity car is a Gunderson Maxi IV. The containers are owned by Pacer Stacktrain. A well car, also known as a double stack car or stack car, is a type of railroad car… …   Wikipedia

  • American President Lines — Ltd. Type Public Industry Shipping Logistics Founded 1849 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.