Self-locking device

Last updated May 18, 2024

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

Types

Prusik sling

The earliest type of self-belay device used was the ubiquitous prusik knotted sling used by climbers. The method requires the solo climber to feed out an estimated length of belay rope so that they can reach their next stance and repeat the process as the rope is difficult to feed through the prusik knot while climbing.

Gibbs-style type 1 ascender

The next level of device development improved on the locking limitations of the prusik sling by utilizing a cam that is activated by the climber's body moving down to rotate the simple grab cam inside a rigid frame. The climber's harness is directly attached to the cam and the frame encapsulates the rope.

Early versions of the cam systems used a Gibbs-style type 1 ascender placed in an inverted position attached to a soloer's sit harness opposite to the manufacturer's intended use. The combination of a climber's body position in a fall and friction between the ascender frame and the rope provides the activating leverage for the cam to grab the rope. Fall forces generated using this device and the cam profile can be enough to damage a rope due to the high clamp loads induced by the cam lever arm. The main drawback to this system is that it is like the prussik knot system where the soloer also has to feed out an estimated amount of rope in order to reach a stance point.

Floating cam ascender

A big improvement over the Gibbs-style type 1 ascender was the design of the Wren Industries "Soloist" – the device incorporates a floating cam that is activated by the relative position of the rope to the device frame, with the frame secured between a user's sit harness and a chest harness. The Soloist allows the rope to feed without the need for the soloer to manually feed out between stances – so it allows a 'true' hands-free climb.

Knowledge of the correct device position relative to the rope anchor is critical for the correct operation of the cam devices in a fall as they are mono-directional in operation, and the soloer must be aware that he needs to put in a runner as soon as he sets off above the belay point on a multi-pitch climb, otherwise he can slide to the bottom of the rope in the event of a fall. The Soloist cam profile design allows the belay rope to be "grasped" rather than crushed as in the early cam devices.

Inertial drum brake ascender

To overcome these limitations, the Wren Industries 'Silent Partner' device was developed. This system has four mechanical moving parts inside a frame that is attached to a climber's sit harness and is basically an inertial drum brake with the belay rope connected to the device by tying a clove hitch around the device's drum. The Silent Partner is unique in the sense that it operates in both directions of drum rotation so it can be attached to a climber's sit harness in either position, eliminating the danger of stepping off a multi-pitch anchor point before the first runner can be placed.

As long as the clove hitch can feed over the drum, the rope will feed through the device. In a fall, the drum is back driven by the rope as the device slides down the rope; when the drum rotation exceeds a certain angular velocity, it locks off to the frame and the increase in friction induced between the stationary drum and the rope causes the clove hitch to rapidly tighten around the locked drum to arrest the fall.

The method used to lock the drum against the device frame is by the use of two straight knurl edge discs that are thrown outwards by centrifugal force as they ride on parallel ramps milled into the drum's enclosed outer periphery. Two light return springs act as centrifugal force trips and as return springs to reset the discs when the fall load is released and the device is unlocked. A simple nylon guide is used to ensure both discs activate simultaneously to jam the discs between each drum ramp and the frame's lock ring.

While the device works quite well, it suffers from rope drag that can prematurely tighten the clove hitch, so allowance must be made to reduce the hanging weight of the rope below the device. The rope diameter and elasticity is critical for operation, as higher than normal fall forces can be generated due to the rapid locking rate, in the order of 13 kN at runners and anchor points.

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<span class="mw-page-title-main">Glossary of climbing terms</span> For rock climbing and mountaineering

Glossary of climbing terms relates to rock climbing, mountaineering, and to ice climbing.

Rock-climbing equipment varies with the type of climbing undertaken. Bouldering needs the least equipment outside of shoes and chalk and optional crash pads. Sport climbing adds ropes, harnesses, belay devices, and quickdraws to clip into pre-drilled bolts. Traditional climbing adds the need for carrying a "rack" of temporary passive and active protection devices. Multi-pitch climbing adds devices to assist in ascending and descending fixed ropes. And finally aid climbing uses unique equipment.

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Lead climbing is a technique in rock climbing where the lead climber clips their rope to the climbing protection as they ascend a pitch of the climbing route, while their second remains at the base of the route belaying the rope to protect the lead climber in the event that they fall. The term is used to distinguish between the two roles, and the greater effort and increased risk, of the role of the lead climber.

Top rope climbing is a form of rock climbing where the climber is securely attached to a climbing rope that runs through a fixed anchor at the top of the climbing route, and back down to the belayer at the base of the climb. A climber who falls will just hang from the rope at the point of the fall, and can then either resume their climb or have the belayer lower them down in a controlled manner to the base of the climb. Climbers on indoor climbing walls can use mechanical auto belay devices to top rope alone.

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<span class="mw-page-title-main">Prusik knot</span> Type of 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 used to tie the hitch and the hitch itself, and the verb is "to prusik" or "prusiking". 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.

In rock climbing, an anchor can be any device or method for attaching a climber, rope, or load to a climbing surface—typically rock, ice, steep dirt, or a building—either permanently or temporarily. The intention of an anchor is case-specific but is usually for fall protection, primarily fall arrest and fall restraint. Climbing anchors are also used for hoisting, holding static loads, or redirecting a rope.

<span class="mw-page-title-main">Single-rope technique</span>

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.

An autoblock is a rope device used in climbing and caving for both rappelling (downward) and ascending (upward).

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<span class="mw-page-title-main">Reverso (climbing)</span> Belay device for climbing

A Reverso is a belay device developed and patented by Petzl, used for example in rock-climbing and other activities which involves rope-work. Another version of this device is the Reversino, intended for use with thinner ropes.

A Grigri is an assisted braking belay device manufactured by Petzl designed to help secure rock-climbing, rappelling, and rope-acrobatic activities. Its main characteristic is a clutch that assists in braking under a shock load. The success of this device has led to grigri becoming a common name for devices of this type. In 2011 a new version, the Grigri 2, was released to replace the original 1991 model. Petzl released the Grigri+ in 2017, adding safety features to the original design, however this added weight and many climbers felt the new safety features were more of a hindrance than a help. 2019 saw the release of an updated version of the device, simply called the Grigri. It is named for the African amulet gris-gris, believed to protect the wearer from evil.

A belay device is a mechanical piece of climbing equipment used to control a rope during belaying. It is designed to improve belay safety for the climber by allowing the belayer to manage their duties with minimal physical effort. With the right belay device, a small, weak climber can easily arrest the fall of a much heavier partner. Belay devices act as a friction brake, so that when a climber falls with any slack in the rope, the fall is brought to a stop.

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.

References

Mountaineering : the freedom of the hills. Cox, Steven M., 1951-, Fulsaas, Kris. (7th ed.). Seattle, WA: Mountaineers Books. 2003. ISBN 0898868289. OCLC 50982399.{{cite book}}: CS1 maint: others (link)

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