Autoblock

{{Short description|Rope device used in climbing and caving}} [[File:Prusik and Autoblock Loops.png|thumb|An autoblock using a Prusik knot on the left and an autoblock using the Machard knot ("autoblock knot") on the right.]]{{Self reference|For autoblock information within the MediaWiki software, see Wikipedia:Autoblock.}} right|thumb

An '''autoblock''' (or '''autobloc''' or '''"third hand"''') is a rope device used in climbing and caving for both rappelling (downward) and ascending (upward).<ref name=":0">{{Cite news|url=https://www.devilslakeclimbingguides.com/blog/autoblock-backup-for-rappelling|title=6-Step Guide to Rappelling with an Autobloc Backup|work=Devils Lake Climbing Guides|access-date=2018-07-10|language=en-US}}</ref><ref name=":1">{{Cite book|url=https://books.google.com/books?id=EU6LBAAAQBAJ|title=Rock Climbing: The AMGA Single Pitch Manual|last=Gaines|first=Bob|last2=Martin|first2=Jason D.|date=2014-05-20|publisher=Rowman & Littlefield|isbn=9781493009626|language=en|quote=Sometimes called the “third hand,” the autoblock is ... friction hitches like the prusik, klemheist, and autoblock}}</ref>

While rappelling, it slides freely down the rope when pushed downward by the hand, allowing a controlled descent, but jams in the event of a sudden drop or loss of control, stopping the descent. This prevents uncontrolled falls in the event of an accident in which the rappeler loses control of the rope.<ref>{{Cite web|title = How to Tie and Use an Autoblock Knot for Climbing|url = http://climbing.about.com/od/climbingknots/ss/HowTieAutoblock.htm|access-date = 2015-04-24|archive-date = 2015-04-04|archive-url = https://web.archive.org/web/20150404124810/http://climbing.about.com/od/climbingknots/ss/HowTieAutoblock.htm|url-status = dead}}</ref> For ascending, it likewise can be pushed up the rope manually when unweighted, but jams and holds when weighted by the body.

It is made using a friction hitch around the rope, connected by a carabiner to the climber's harness, and may be combined with other climbing equipment for further safety.<ref>{{Cite web|title = 6-Step Guide to Rappelling with an Autoblock Backup|url = http://www.devilslakeclimbingguides.com/blog/autoblock-backup-for-rappelling/|access-date = 2015-04-24}}</ref> For instance, it is typically used as a backup while rappelling using a tube belay device.<ref name=":0" />

The term '''autoblock''' is also used for a specific type of friction hitch,<ref>{{Cite web|url=http://dyeclan.com/outdoors101/canyoneering101/?page=autoblock-belay|title=Canyoneering 101 - Autoblock {{!}} The Dye Clan|website=dyeclan.com|access-date=2018-07-09|quote=The term "autoblock" is kind of ambiguous as it refers to both the knot and the system. As such, you can create an autoblock system with the autoblock knot, a Klemheist (French Prusik), or a valdôtain tresse.}}</ref><ref name=":1" /><ref>{{Cite book|url=https://archive.org/details/rockclimbingoutd00wild|title=Rock climbing|date=2009|publisher=Human Kinetics|others=Kidd, Timothy W., Hazelrigs, Jennifer., Wilderness Education Association (U.S.)|isbn=9780736068024|location=Champaign, IL|oclc=251227945|quote=Examples of appropriate hitches include autoblock, klemheist, and Prusik|url-access=registration}}</ref> which is also known as a '''French prusik''' or '''Machard knot''', named after its inventor, Serge Machard.<ref>{{Cite web|url=http://www.summitpost.org/the-machard-knot/936995|title=The Machard Knot|access-date=2016-10-20|quote=the Knot invented in 1961 by Serge Marchard, a young climber from Marseille}}</ref><ref>{{Cite web|url=http://cafmarseille.free.fr/spip.php?article553|title=Le noeud Machard et son histoire - CAF Marseille Provence|last=Vola|first=Eric|date=2016-06-03|language=fr|archive-url=https://web.archive.org/web/20160603041436/http://cafmarseille.free.fr/spip.php?article553|archive-date=2016-06-03|access-date=2018-07-09|quote=[from French] Serge had sent André a letter on December 28, 1961 which among other things included the description of his knot. The two diagrams of his letter are reproduced here.}}</ref>

Other friction hitches that can be used to build an autoblock system include the Prusik knot, Klemheist knot, and Bachmann knot.

The Ashley Book of Knots #505.

==See also== *List of knots

== References == <references />

==External links== *{{Animated Knots|klemheist|The Klemheist|May 5, 2013}} *[http://www.chockstone.org/TechTips/RapBackup.htm Backing up an Abseil]

Category:Climbing knots Category:Caving Category:Climbing techniques Category:Caving techniques Category:Rappelling equipment