Vertical caving terminology and methods > Personal SRT gear
A simpler version of the Stop, which has no automatic locking system. This works using the characteristic S-shape of rope wrapped around two metal bobbins, common to almost all bobbin descenders, where the up rope comes out of the bottom of the descender, and the down rope comes out of the top of the descender. Locking off can be relatively easily done with a hard lock, but there is no soft lock unless a braking carabiner is also being used. The bobbins become very hot in use, and can easily singe a rope, especially on longer descents. Ropes may be intentionally wetted in order to reduce this risk. Difficult to use on very long ropes, because the weight of the rope adds too much friction.
In 1865, German fire brigades used an Archimedian scroll descender which operated on exactly the same principle as the Simple, with the two bobbins attached directly to a waist belt side by side instead of above each other. The friction was said to be fairly low, and the rope needed to be prepared using rosin to make it grip more once the bobbins wore down, but this is probably because of the orientation of the bobbins, and because they did not expect speed to be controlled with a hand. This approach for a descender was then described as a fire escape system by American E. K. Graves in 1878, but with two extra bends that the rope had to twist around. After a couple of others used the same approach, American Oscar F. Davis changed the orientation to match the Simple in 1882, and added a lever to adjust the friction. In about 1930, Henri "Kiki" Brenot created the Frein de Descente descender in the Grenoble region of France. It was based on the same weaving principle as a rack, with 4 fixed bars and a removable front. The number of bars could be varied if fewer were needed. Cavers then learned that by using the bars in the wrong order, and therefore wrapping the rope further around each bar, they could reduce the requirement down to 2 thicker bars, which became the bobbins of the Simple. French caver Bruno Dressler made the first Simple in the Grenoble region of France in the 1960s, before giving the design to the founder of Petzl, who released their Simple in 1968 (before Petzl existed as a company). The modern versions look almost exactly the same (with some paint) and function in the same way. The Simple was advertised in the first British Descent magazine in 1969, and was originally known as the "Roulette" in France and Britain.
This history section only covers the Simple. 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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