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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. Prusik and Autoblock Loops.png
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.

The Ashley Book of Knots #505.

See also

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Knot Method of fastening or securing linear material

A knot is an intentional complication in cordage which may be practical or decorative, or both. Practical knots are classified by function, including hitches, bends, loop knots, and splices: a hitch fastens a rope to another object; a bend fastens two ends of a rope to each another; a loop knot is any knot creating a loop, and splice denotes any multi-strand knot, including bends and loops. A knot may also refer, in the strictest sense, to a stopper or knob at the end of a rope to keep that end from slipping through a grommet or eye. Knots have excited interest since ancient times for their practical uses, as well as their topological intricacy, studied in the area of mathematics known as knot theory.

Traditional climbing Style of rock climbing

Traditionalclimbing, is a style of rock climbing in which a climber or group of climbers place all gear required to protect against falls, and remove it when a pitch is complete. Traditional bolted face climbing means the bolts were placed on lead and/or with hand drills. The bolts tend to be much farther apart than sport climbs. For example, a trad bolted route may have bolts from 15–75 feet apart. A sport route may have bolts from 3–10 feet apart, similar to a rock climbing gym. The term seems to have been coined by Tom Higgins in the piece "Tricksters and Traditionalists" in 1984. A trad climber is called a traditionalist.

Klemheist knot

The klemheist knot or French Machard knot is a type of friction hitch that grips the rope when weight is applied, and is free to move when the weight is released. It is used similarly to a Prusik knot or the Bachmann knot to ascend or descend a climbing rope. One advantage is that webbing can be used as an alternative to cord. The Klemheist is easier to slide up than a Prusik. The klemheist is also a way to attach a snubber to the anchor rope of small boats, with the advantage that it is easy to undo.

Glossary of climbing terms List of definitions of terms and concepts related to rock climbing and mountaineering

This glossary of climbing terms is a list of definitions of terms and jargon related to rock climbing and mountaineering. The specific terms used can vary considerably between different English-speaking countries; many of the phrases described here are particular to the United States and the United Kingdom.

Rock-climbing equipment

A wide range of equipment is used during rock or any other type of climbing that includes equipment commonly used to protect a climber against the consequences of a fall.

Abseiling Rope-controlled descent of a vertical surface

Abseiling, also known as rappelling, is a controlled descent off a vertical drop, such as a rock face, using a rope.

Crevasse rescue

Crevasse rescue is the process of retrieving a climber from a crevasse in a glacier. Because of the frequency with which climbers break through the snow over a crevasse and fall in, crevasse rescue technique is a standard part of climbing education.

Self-locking devices are devices intended to arrest the fall of solo climbers who climb without partners. This device is used for back rope solo climbing for "ground-up climbing" or "top rope self belaying". To date, several types of such self-locking devices have evolved.

Belaying Rock climbing safety technique using ropes

Belaying is a variety of techniques climbers used to create friction within a climbing system, in particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of the rope whenever the climber is not moving, and removes the tension from the rope whenever the climber needs more rope to continue climbing.

Icicle hitch

An icicle hitch is a knot that is excellent for connecting to a post when weight is applied to an end running parallel to the post in a specific direction. This type of hitch will hold its place even when holding a substantial load on a smooth surface. One can even suspend from a tapered post with this knot.

Munter hitch Adjustable knot used control friction in a belay system

The Munter hitch, also known as the Italian hitch, Mezzo Barcaiolo or the Crossing Hitch, is a simple adjustable knot, commonly used by climbers, cavers, and rescuers to control friction in a life-lining or belay system. To climbers, this hitch is also known as HMS, the abbreviation for the German term Halbmastwurfsicherung, meaning half clove hitch belay. This technique can be used with a special "pear-shaped" HMS locking carabiner, or any locking carabiner wide enough to take two turns of the rope.

Bachmann knot

The Bachmann hitch is a friction hitch, named after the austrian alpinist Franz Bachmann. It is useful when the friction hitch needs to be reset quickly/often or made to be self-tending as in crevasse and self-rescue.

Offset overhand bend

The offset overhand bend is a knot used to join two ropes together. The offset overhand bend is formed by holding two rope ends next to each other and tying an overhand knot in them as if they were a single line. Due to its common use in several fields, this bend has become known by many names, such as thumb knot, openhand knot, one-sided overhand knot or flat overhand bend (FOB), though the terms "one-sided" and "flat" are considered incorrect.

Blakes hitch

The Blake's hitch is a friction hitch commonly used by arborists and tree climbers as an ascending knot. Unlike other common climbing hitches, which often use a loop of cord, the Blake's hitch is formed using the end of a rope. Although it is a stable knot, it is often backed up with a stopper knot, such as a figure-of-eight knot, for safety. It is used for both ascending and descending, and is preferred by many arborists over other hitches, such as the taut-line hitch, as it is less prone to binding.

Ascender (climbing) Devices used for ascending, braking, or protection in climbing

An ascender is a device used for directly ascending a rope, or for facilitating protection with a fixed rope when climbing on very steep mountain terrain.

Prusik knot

A Prusik is a friction hitch or knot used to attach a loop of cord around a rope, applied in climbing, canyoneering, mountaineering, caving, rope rescue, ziplining, and by arborists. The term Prusik is a name for both the loops of cord and the hitch, and the verb is "to prusik". More casually, the term is used for any friction hitch or device that can grab a rope. Due to the pronunciation, the word is often misspelled Prussik, Prussick, or Prussic.

Single-rope technique

Single-rope technique (SRT) is a set of methods used to descend and ascend on the same single rope. Single-rope technique is used in caving, potholing, rock climbing, canyoning, roped access for building maintenance and by arborists for tree climbing, although to avoid confusion in the tree climbing community, many have taken to calling it "stationary" rope technique.

Distel hitch

Distel hitch is a friction hitch knot used to attach a carabiner to a rope, allowing a climber to descend or ascend. The knot is similar to the prusik knot, however it grips the rope more consistently, making for increased climber control.


  1. 1 2 "6-Step Guide to Rappelling with an Autobloc Backup". Devils Lake Climbing Guides. Retrieved 2018-07-10.
  2. 1 2 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". 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 PrusikCS1 maint: others (link)
  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.