Autoblock Explained

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.

The term autoblock is also used for a specific type of friction hitch,^{[5] [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.

The Ashley Book of Knots #505.

See also

• List of knots

References

1. News: 6-Step Guide to Rappelling with an Autobloc Backup. Devils Lake Climbing Guides. 2018-07-10. en-US.
2. Book: Gaines, Bob. Rock Climbing: The AMGA Single Pitch Manual. Martin. Jason D.. 2014-05-20. Rowman & Littlefield. 9781493009626. en. Sometimes called the “third hand,” the autoblock is ... friction hitches like the prusik, klemheist, and autoblock.
3. Web site: How to Tie and Use an Autoblock Knot for Climbing. 2015-04-24. 2015-04-04. https://web.archive.org/web/20150404124810/http://climbing.about.com/od/climbingknots/ss/HowTieAutoblock.htm. dead.
4. Web site: 6-Step Guide to Rappelling with an Autoblock Backup. 2015-04-24.
5. Web site: Canyoneering 101 - Autoblock The Dye Clan. dyeclan.com. 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. Book: Rock climbing. 2009. Human Kinetics. Kidd, Timothy W., Hazelrigs, Jennifer., Wilderness Education Association (U.S.). 9780736068024. Champaign, IL. 251227945. Examples of appropriate hitches include autoblock, klemheist, and Prusik. registration.
7. Web site: The Machard Knot. 2016-10-20. the Knot invented in 1961 by Serge Marchard, a young climber from Marseille.
8. Web site: Le noeud Machard et son histoire - CAF Marseille Provence. Vola. Eric. 2016-06-03. fr. https://web.archive.org/web/20160603041436/http://cafmarseille.free.fr/spip.php?article553. 2016-06-03. 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..

External links

• • Backing up an Abseil