An auto belay (or autobelay) is a mechanical device for

belaying In climbing and mountaineering, belaying comprises techniques used to create friction within a climbing protection system, particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies ...

indoor climbing A climbing wall is an artificially constructed wall with manufactured grips (or "holds") for the hands and feet. Most walls are located indoors, and climbing on such walls is often termed indoor climbing. Some walls are brick or wooden constr ...

wall A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or serves a decorative purpose. There are various types of walls, including border barriers between countries, brick wal ...

s, in both training and

competition climbing Competition climbing is a form of regulated rock climbing, rock-climbing competition held indoor climbing, indoors on purpose-built artificial climbing walls (earlier versions were held on external natural rock surfaces). The three competition ...

formats. The device enables a climber to ascend indoor routes on a top rope but without the need for a human belaying partner. The device, which is permanently mounted in a fixed position at the top of the route, winds up a tape or steel wire to which the ascending climber is attached. When the ascending climber sits back, or falls, the auto belay automatically brakes and smoothly lowers the climber to the ground.

Types

Braking

Braking methods are

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

hydraulic Hydraulics () is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counterpart of pneumatics, which concer ...

, and based on

centrifugal force Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...

. The ''electro-magnetic'' method uses the

Eddy current brake An eddy current brake, also known as an induction brake, Faraday brake, electric brake or electric retarder, is a device used to slow or stop a moving object by generating eddy currents and thus dissipating its kinetic energy as heat. Unlike fr ...

principle. It requires a conductive disk that rotates through the magnetic field of a strong

permanent magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, c ...

. When the disk moves, the magnet exerts a

drag force In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or b ...

on the metal which opposes its motion, due to circular

electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...

s called eddy currents induced in the metal by the

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

. The braking force is proportional to the weight of the climber. As the magnet and disk are not in mechanical contact, this system does not wear off from braking. The ''hydraulic'' method employs a closed system filled with oil and pressurized air. The braking effect is created by a valve, limiting the oil flow. The system does not adjust to the weight of the climber and is difficult to maintain The method employing the ''centrifugal force'' moves braking pads against a drum when the system rotates during descent. The wear-and-tear is the highest for this method.

Lead

While traditional auto belays use a top roping format with the device hanging from the top of the route, in 2021, a new type of auto belay–the lead auto belay–was developed that used a

lead climbing Lead climbing (or leading) is a technique in rock climbing where the 'lead climber' Glossary of climbing terms#clip in, clips their rope to the climbing protection as they ascend a pitch (climbing), pitch of the climbing route, while their 'seco ...

format (i.e. the climber clipped into the

quickdraws QuickDraw was the 2D graphics library and associated application programming interface (API) which is a core part of classic Mac OS. It was initially written by Bill Atkinson and Andy Hertzfeld. QuickDraw still existed as part of the libraries ...

like a normal lead climb on a

sport climbing Sport climbing (or bolted climbing) is a type of free climbing in the sport of rock climbing where the Lead climbing, lead climber clips their climbing rope, rope — via a quickdraw — into pre-drilled in-situ bolt (climbing), bolts for their ...

route), where the device was fixed to the bottom of the route.

Operation

Climber training in speed route with Autobelay 8766e

The main purpose of auto belay devices is the immediate capture of a falling climber, and the controlled descent of the climber once the route is finished (or after the climber has fallen). While a human belay partner is able to tighten the rope on the climber's demand to allow the climber to take a rest on the route before re-trying a sequence (i.e. hangdogging), the auto belay will not "hold" the climber and will instead begin to lower the climber smoothly as soon as they lose contact with the wall. In recent years, more advanced devices, such as the Trublue iQ+ Auto Belay, contain a secondary braking system and electronic communication, allowing climbers to remain on the wall after a fall, without immediately lowering ("catch-and-hold" mode). This rest period allows climbers to "project" more difficult routes in a style that is more similar to top roping with a human belay partner. The climber's rate of ascent must not exceed the speed at which the device takes in the wire or tape, to avoid creating slack. Devices specifically for competition speed climbing are therefore constructed with a very quick take-in time, i.e. 15 m in 3.2–3.5 s, which is faster than the world record.

Dangers

There have been a number of serious, and some fatal, accidents regarding the use of auto belay devices in indoor climbing walls. Reasons include: * Tired climbers forgetting to re-clip into the auto belay wire or tape on a route that they are continuously repeating. * Devices no longer retracting the tape or wire lanyard, either because they are jammed or the spring is broken. When the climber continues the ascent, this creates slack, thus as the lanyard is not designed to absorb energy, the climber and the device are shock-loaded. * Assembly mistakes during installation or after maintenance. To mitigate these risks, climbers are recommended to take a test fall early in the process of climbing at a height that is sufficiently high that the device will engage fully, but at which falling would be less serious than at a greater height.

Standards

* EN 360:2002:

Personal protective equipment Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, elect ...

against falls from a height - Retractable type fall arresters * EN 341:2011 Class 1A: Personal protective equipment against falls from a height – Descender devices

References

External links

Auto-belays: How not to muck it up
Association of Mountaineering Instructors (2023)
Autobelay Safety
Association of British Climbing Walls (2022)
VIDEO: Be a better climber: check your autobelay

British Mountaineering Council The British Mountaineering Council (BMC) is the national representative body for England and Wales that exists to protect the freedoms and promote the interests of climbers, hill walkers and mountaineers, including ski-mountaineers. The BMC ...

(2021) {{Climbing navbox Climbing equipment Indoor climbing Speed climbing