Autoblock

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An autoblock using a Prusik knot on the left and an autoblock using the Machard knot ("autoblock knot") on the right.

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]

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

References[edit]

  1. ^ a b "6-Step Guide to Rappelling with an Autobloc Backup". Devils Lake Climbing Guides. Retrieved 2018-07-10.
  2. ^ a b Gaines, Bob; Martin, Jason D. (2014-05-20). Rock Climbing: The AMGA Single Pitch Manual. Rowman & Littlefield. ISBN 9781493009626. Sometimes called the “third hand,” the autoblock is ... friction hitches like the prusik, klemheist, and autoblock
  3. ^ "How to Tie and Use an Autoblock Knot for Climbing". Retrieved 2015-04-24.
  4. ^ "6-Step Guide to Rappelling with an Autoblock Backup". Retrieved 2015-04-24.
  5. ^ "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.
  6. ^ Rock climbing. Kidd, Timothy W., Hazelrigs, Jennifer., Wilderness Education Association (U.S.). Champaign, IL: Human Kinetics. 2009. ISBN 9780736068024. OCLC 251227945. Examples of appropriate hitches include autoblock, klemheist, and Prusik
  7. ^ "The Machard Knot". Retrieved 2016-10-20. the Knot invented in 1961 by Serge Marchard, a young climber from Marseille
  8. ^ Vola, Eric (2016-06-03). "Le noeud Machard et son histoire - CAF Marseille Provence" (in French). Archived from the original on 2016-06-03. Retrieved 2018-07-09. [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.

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