Vertical caving terminology and methods > Personal SRT gear
A larger descender favoured in the USA. Uses a number of metal bars to create friction, which can be moved or disabled in order to alter the friction, making it usable on a very wide range of rope lengths. The rope weaves alternately in front of and behind one bar at a time. Descent is smoother than most other popular descenders, but it is harder to use in some situations, and takes longer to attach. Speed can be controlled much more than with other descenders. If disabling some bars at the top of a hang, it is very important to re-enable them as needed when the weight of the down rope decreases during the descent, to avoid an uncontrolled descent. Dissipates heat much better than most other descenders, and is less likely to singe the rope. Can work with single or doubled ropes, and ropes of almost any standard diameter. Locking off is quite clumsy, with soft locks being possible only on some designs, and hard locks need a lot of excess. Several designs, with the most common being an open frame J rack, and the second being a closed U rack. Most designs allow the user to freely reconfigure their rack bars, to swap bars around to even the wear across all bars, to change whether the first bar is threaded from the front or back, or whether the bars hinge on the left or right. However, this should only ever be done by a skilled user, as changes may be confusing, may remove safety features, or can make the rack dangerous. And of course, any modification (such as the one pictured) is likely to be contrary to the manufacturer's PPE instructions and/or invalidate warranties, so anyone choosing to make modifications must ensure that they are fully aware of the implications.
A Belgian inventor created a device that functioned exactly like a rack, which was presented at an international rescue conference in 1876. The number of bars could not be changed during use, and it could only be threaded on to the start of the rope. By 1877, descenders based on the Belgian design were being sold by German fire brigade suppliers from southern parts of the German Empire (now Germany), such as Magirus in Ulm. American James Jerome van Wie created an almost identical design in 1877. Americans William N. Clark, James B. Clark and William N. Clark Jr. created another design in 1877 that functioned like a rack, but with a lever that could squeeze the rope to adjust the friction during use. These American designs were registered on the same day in different places, and seem to be independent inventions, but appeared some time after the Belgian and German designs, and were likely to have been derived from the Belgian design. Further designs used the same approach in 1884 in Canada, 1886 in Germany, 1887 in Germany and 1890 in the USA. In about 1930, in the Grenoble region of France, Henri "Kiki" Brenot created the Frein de Descente caving descender, which functioned like a rack by weaving the rope between a variable number of friction bars, but with fixed bars attached to one plate like a Simple, and a removable front. The French model allowed the number of bars to be varied if the rope needed less friction, and used an eccentric cam as an emergency brake. Carabiners were used with brake bars by mountaineers in North America since some time before 1933. They were used by the American military in the years they were involved in World War II; 1941-1945. In 1942, the mountaineering booklet Anwendung des Seiles published by the Bavarian section of the German Alpine Club showed a carabiner with a brake bar, which was said to have been based on the approach used by mountaineer Ludwig Gramminger, and popular for a few years already. It is not known if he developed it before the American climbers, or whether he got the idea from them, but it is very unlikely that they were independent inventions. Using interlinked carabiners as brake bars was common in North America by the 1960s, described by American caver Tom Perera in 1962, but like actual brake bars, these could be very dangerous, as the brake bars pushed sideways on the gates of the carabiners, and could break them open. The first proper devices that look like a modern rack were made independently by Americans John W. Cole and Warren Lewis, both in 1966. In 1967, American Gerald Wood created the Whaletail, a version of the rack milled from a single block of aluminium, with one side open, holding the rope in place with small protrusions. The bars were not adjustable, but the heat dissipation was better than a standard rack. These were popular for a while, but lost out to the regular rack after some serious safety incidents. John Grindstaff created the hyper bar, then called a "John-Bar" around 1970. Petzl released their rack in 1987, which is one of the very few European racks still in existence.
This history section only covers racks. This article also has a detailed history of many of the other devices and techniques that are used for vertical caving.
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