Belay device
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Belay devices are mechanical pieces of climbing equipment used to control a rope during belaying. They are 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 purposely do not instantly 'lock' to arrest a fall, since an instant stop from a fall during lead climbing would probably injure the climber or cause all the protection devices to fail. Instead, 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 over a finite (but reasonably short) distance.
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 a climbers 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.
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[edit] Types of Belay Devices
[edit] Sticht plate
The original belay device, named for its designer. It consists of a metal disk with one or two holes drilled through. A wide wire spring is attached on one side. The rope is threaded through from the side without the spring through a locking carabiner and back through the same drilled hole. The locking carabiner is attached to the belayer who is then able to lock the rope at will.
Nowadays, Sticht plates are becoming less popular since more modern designs provide smoother control over the rope and are less prone to jamming, especially when doubling as a descender.
[edit] ATC/Tubular Devices
The ATC is a very popular proprietary design by Black Diamond. It is designed to facilitate slow and smooth feeding of the rope, and has a large surface area to dissipate heat away from the rope. These are significant improvements over the original Sticht plate but both devices are still used similarly.
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[edit] Reverso
The Reverso is a device patented by Petzl, that functions in a similar way to the ATC. It allows belaying and rapelling.
[edit] Gri-Gri
A Gri-gri is a belay device that automatically locks the rope in the event of a fall. Because of the self-locking mechanism, it is more difficult to pay out slack on a Gri-Gri than on an ATC and modified belay techniques are widely used. Gri-gri's reportedly give a harder catch than a regular belay device because they allow less rope slippage when catching a hard fall. They are a proprietary design by Petzl. The Gri-gri is a preferred device for belaying the follower directly off the anchor because, unlike other devices marketed for the purpose (the Trango B-52 and the Petzl Reverso), lowering the follower is quite easy. Trango sells a similar self-locking belay device called the Cinch that is rated to work on ropes 9.4 to 11 mm (the Gri-Gri is rated from 10 to 11 mm).
[edit] Figure eight
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.
[edit] Self Belay Devices
Self belay devices are designed to allow Solo climbing where the climber wears the belay device. These devices automatically lock without any intervention when placed under sufficient load (during a fall), but allow rope to move relatively freely whilst climbing.
