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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.
Belay devices generally have two modes of operation: in the first mode, the rope is relatively free to be payed in/out by the belayer. The second mode, which allows the belayer to arrest the descent of a climber in the case of a fall, functions by forcing the rope(s) into tight bends where the rope rubs against the belay device and/or against itself. This rubbing slows the rope, but also generates heat. Some types of belay devices can transition between these modes without the belayer taking any action, others require the belayer to hold or pull the rope in a particular direction to arrest a fall.
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 devices on the market which allow a climber to climb solo in his or her climbing gym.
Types of belay devices
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 lock 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. 9mm and 11mm. 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 sold 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.
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.
Besides arresting the fall of a climber, these devices can also be used for rappelling.
Sometimes just called "eight", this device is most commonly used as a descender. A figure eight can be used for belaying, and indeed 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 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.
Referred to as assisted braking or, incorrectly as 'auto-locking', under the right conditions these devices, either mechanical or static, use the load on the rope to prevent the brake line from being pulled through the device. Use of such belay devices should never be instructed as self- or auto-locking, but as assisted braking. There do exist rare conditions where these devices' braking functions may not apply correctly, though accident statistics show that these incidents are often user-error. An icy, muddy, old, too-thin of a rope, or possibly other conditions, such as insufficient training and experience, may affect a device's braking function.
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.
Tubular device variant
A similar device to the traditional tubular belay device which has two extra loops; normally situated on the front and back of the device. 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. The device is also able to be used as a standard tubular device when belaying from the harness.
Statistically, by sales volume, the Grigri is the most popular mechanical assisted-braking belay device. A Grigri, when properly used, assists in braking the rope with a camming device that clamps the rope in the event of a fall. Because of the braking mechanism, modified belay techniques are widely used, though Petzl, the device's manufacturer, has approved only certain techniques for instructing new belayers. Grigris reportedly give a harder catch than a regular belay device because they allow little to no rope slippage when catching a fall. On the upside, this is offset by the fact that the person being belayed falls a shorter distance. They are a proprietary design by Petzl.
The original Grigri is rated for 10 to 11 mm single ropes, while the newer, smaller Grigri 2 is rated for 8.9 to 11 mm single ropes and optimized for 9.4 to 10.3 mm ropes. Trango sells a similar assisted braking belay device called the Cinch that is rated to work on ropes 9.4 to 11 mm.
Using a Grigri to bring up a second on a traditional anchor is however less favorable than other belay devices because the Grigri gives a more static catch with little to no rope slippage. This increases the amount of force exerted on the anchor which, in turn, increases the chance of anchor failure.
Self-belay devices are designed to allow solo climbing where the climber wears the belay device, or secures it to a fixed object on the ground. These devices automatically lock without any intervention when placed under sufficient load (during a fall), but allow rope to move relatively freely whilst climbing.
Auto-belay devices allow climbers to practice without a second person for belaying. These devices usually hang on or are attached to an artificially made climbing wall. There are several different types of auto-belay device, including ones that run on hydraulics, magnetic braking technology, and friction.
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