Carabiners are locking gated metal connective devices that are used to make safe, critical links in mountain climbing gear. These ring like pieces of equipment open inward on one side of the ring and return outward to form a close loop through which ropes and other connective devices are placed. Carabiners fall into two main categories: non-locking and locking.
Non-Locking Carabiners
Non locking carabiners snap open and shut when pressure is put on the gate, but do not close in a locking fashion. That is, they can always be opened by pushing the gate. They are designed this way for speed and ease of clipping to rope and various pieces of mountaineering equipment. Here are some of the main types of non-locking carabiners:
Oval Snap Gate Carabiners
These types of carabiners are oval in shape. These are often the least expensive carabiner type and weigh the least. They are often used to clip various non critical items to a climbing harness or at least ones that will not take the highest amount of stress.
Symmetrical “D” Shaped Snap Gate Carabiners
These are shaped like a standard “D.” The straight part of the D is called the spine. The curved parts of the D make rope or other equipment placed in the carabiner slide back toward the spine. This makes the D shape stronger than the standard oval.
The D shaped carabiner has three variations as regards the gate: Straight Gate, Bent Gate, and Wire Gate. The straight gate only opens along the straight part of the curved side of the D. This is common and generally the least expensive type. Bent gate carabiners have a curved gate that both allows more room for rope inside the loop and clips more quickly than straight gate D carabiners. They may also be a bit more prone to becoming accidentally unhooked however. A runner and quickdraw can help solve this problem. Wire gate carabiners have a thin, wire-like gate that is less apt to pop open in the case of a fall (a phenomenon called “gate lash”) due to the gate weighing less and thus having less momentum. These types of snap gate carabiners also are less prone to icing up in winter climbing conditions.
Asymmetrical “D” Shaped Snap Gate Carabiners
These carabiners are shaped like a “D” but have an extra angle that corresponds with the gate (opening part of the loop). The angle allows it to clip more easily. It is good for lead climbing since it allows for especially fast clipping.
Locking Carabiners
Locking carabiners can be permanently closed. When especially critical links are made, it is safest to be able to close a carabiner securely – i.e. making sure that it can’t accidentally open if something puts pressure on it. The locking sleeve must then be either be twisted or unscrewed to unlock the gate. Here are some of the main types of locking carabiners:
Twist/Screw Lock Gates
These types of locking gates use a sleeve that screws into place over the gate, keeping it securely closed. In order for the mountaineer to open the gate, he must unscrew the locking sleeve.
Auto Locking/Spring Locking Gates
With this type of auto locking gate the locking sleeve springs into place automatically by spring action. When it snaps into place the gate is locked shut and cannot open again until the mountaineer unlocks it manually. The potential problem with this sort of gate is that if the spring malfunctions that gate will not stay locked. It is also somewhat more difficult to operate with one hand because the spring sleeve must be held open to remove rope or other equipment from the carabiner.
The main use of these carabiners is, as noted above to form links between mountaineering gear. Usually this takes the form of a climbing harness worn by the climber being attached to a rope or rope ascender device. They can also be used to attach rope to sequentially ascending pitons or hooks hammered into rock faces. Sometimes they serve less intensive functions as simple clips attached to mountaineering harnesses or clothing to which equipment is attached when not in use.
Carabiners have to be strong and durable to withstand the pressures, pulls, and yanks that are involved in steep climbing. Anyone buying carabiners should get proper instruction in how to use them from a professional climber or climbing instructor and make sure to buy durable, reliable equipment.