An autoblock using a Prusik knot on the left and an autoblock using the Machard knot ("autoblock knot") on the right.
For autoblock information within the MediaWiki software, see Wikipedia:Autoblock.
An autoblock (or autobloc or "third hand") is a rope device used in climbing and caving for both rappelling (downward) and ascending (upward).[1][2]
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 abseiler loses control of the rope.[3] 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.[4] For instance, it is typically used as a backup while rappelling using a tube belay device.[1]
The term autoblock is also used for a specific type of friction hitch,[5][2][6] which is also known as a French prusik or Machard knot, named after its inventor, Serge Machard.[7][8]
^ abGaines, Bob; Martin, Jason D. (2014-05-20). Rock Climbing: The AMGA Single Pitch Manual. Rowman & Littlefield. ISBN9781493009626. Sometimes called the "third hand," the autoblock is ... friction hitches like the prusik, klemheist, and autoblock
^"Canyoneering 101 - Autoblock | The Dye Clan". dyeclan.com. Retrieved 2018-07-09. 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.
^Rock climbing. Kidd, Timothy W., Hazelrigs, Jennifer., Wilderness Education Association (U.S.). Champaign, IL: Human Kinetics. 2009. ISBN9780736068024. OCLC251227945. Examples of appropriate hitches include autoblock, klemheist, and Prusik{{cite book}}: CS1 maint: others (link)
^"The Machard Knot". Retrieved 2016-10-20. the Knot invented in 1961 by Serge Marchard, a young climber from Marseille
