ArticleslgStudy

science

Belay device

Belay device is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Belay device rather than just read about it. In short: 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.

Belay device — main illustration
Belay device — illustration

Key takeaways

  • Belay device belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Belay device to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Belay device from memory before moving on to harder problems.

Reference excerpt

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. Belay devices act as a friction brake, assisting the belayer in arresting motion of the rope when a climber falls. Typically, when the rope is held outward, away from the body, it moves relatively freely, so the belayer can take up or pay out slack. When the rope is brought backward, to the side of the body, the rope is forced into tight bends and rubs against the device and/or against itself, allowing the belayer to arrest the descent of a climber in the case of a fall. This rubbing slows the rope, but also generates heat. Some types of belay devices can arrest a fall without the belayer taking any action, while others require the belayer to hold or pull the rope in a particular direction. Belay devices usually attach to the harness of the belayer via a carabiner, and are usually made of aluminium or an alloy. Some belay devices can also be used as descenders for a controlled descent on a rope, that is abseiling or rappeling. Many belay devices can be used to control either one rope, or two ropes in parallel. There are many reasons why the two-rope option might be chosen by a climber, including the consideration of reducing rope drag. There are also auto-belay devices on the market which allow a climber to climb solo in their climbing gym.

Types

Aperture This is a device that you feed a bight (loop) of rope through a hole or aperture and then clip it into a carabiner on the harness.

Sticht plate

The Sticht plate was the first mechanical rope brake, named after its designer, Fritz Sticht. It consists of a small metal plate with a slot that allows a bight of rope to pass through to a locking carabiner and back out. This locking carabiner is clipped to the belayer who is then able to arrest the rope at will. Some plates had two slots for double ropes. The slots could also be different sizes for different diameter ropes e.g. 9 mm and 11 mm. A wide wire spring may be attached on one side to help keep the plate away from the brake carabiner to ease feeding and taking in rope. A smaller hole is often present for accessory cord to carry the device. Sticht plates are typically forged from aluminium alloy in a round disc shape, although other shapes such as rounded rectangles were also made. Although any belaying plate with one or two slots is often called a Sticht plate, Fritz Sticht originally patented the design with Hermann Huber for Salewa GmbH in 1970, who sells it as the Salewa Sticht Bremse (Sticht Brake). Sticht plates have become less popular since more modern designs provide smoother control over the rope and are less prone to jamming, especially when doubling as a descender.

Tubular

Also called a "tube", this type of device generally has a tubular or rectangular shape. It is an evolution of the Sticht plate's concept by creating more surface area to dissipate heat and the ability to create sharper angles which creates a stronger degree of friction which has greater stopping power. As a result, this is generally the most common type of belay device used. The most common form of this kind of tubular belay device is the ATC, an acronym for "air traffic controller". Besides arresting the fall of a climber, these devices can also be used for rappelling. Climbers can control rope descent and arrest falls by creating friction between the device and the rope.

Figure eight

Sometimes just called an "eight", this device is most commonly used as a descender. A figure eight belay devices are used for belaying. There are some which are designed specifically for belaying, however they are not generally popular due to the tendency to twist the rope. There are also variations on this design including DMM's "cardiac arrester" which does the same thing but in which the larger loop is shaped like a heart. It is designed to help stop rope twisting. Figure eights, although not the most common belay device, are still frequently found in use. For most uses, a tubular style belay device is easier and safer to use. Due to their tendency to twist rope and general disagreement about their safety, figure eights are often banned in climbing gyms.

Assisted braking Under the right conditions, assisted braking devices (ABDs) use a sudden load on the rope to engage a camming mechanism (known as active, or mechanically assisted braking devices) or pull the belay carabiner into a pinch point (known as passive, or geometrically assisted braking devices) to prevent the rope from passing through the belay device. The terms "self-" or "auto-locking" are discouraged, because it is necessary to always keep the brake hand on the rope, there being conditions outside the correct function of braking, for example icy, muddy, worn, or too-thin of a rope, and insufficient training and experience.

Guide plate A guide plate, also known as an auto-blocking belay device, is a metal plate with an elongated slot for the bight to go through and then a carabiner is attached so that when pull from the climber occurs the carabiner will be pulled to lock off the device. Examples include the GiGi by Kong.

ATC in Guide Mode

A similar device to the traditional tubular belay device with two extra loops, normally situated on the front and back, that can also be used as a regular tubular device to belay from a harness. When the device is attached directly to an anchor point with the use of a second carabiner through the larger of the two loops it performs a similar stopping function to that created with the guide plate.

Grigri

… excerpt ends here. Continue reading the full article.

Illustrations

Belay device: Petzl Reverso, Verso, GRIGRI
Petzl Reverso, Verso, GRIGRI
Belay device: Sticht plate.
Sticht plate.
Belay device: A Tubular Belay device
A Tubular Belay device
Belay device: A figure-eight descender.
A figure-eight descender.
Belay device: Petzl Reverso
Petzl Reverso

Worked examples

Example 1 — a first encounter with Belay device

Start with the simplest possible case. Write down what Belay device claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Belay device before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Belay device ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Belay device

In research
Belay device appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Belay device in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Belay device is common in secondary-school and first-year university syllabi. It links to neighbouring topics Climbing equipment, Mountaineering equipment, so understanding it makes those chapters shorter.
In everyday life
Look for Belay device outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Belay device in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Belay device means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Belay device out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Belay device in simple terms?

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.

Why does Belay device matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Belay device?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Belay device.

Tags

  • Climbing equipment
  • Mountaineering equipment

Keep exploring