A tricam ( lat. Tri "three", English cam "cam") is a mobile, that is, removable climbing protection that is anchored in predominantly hole-like cracks , crevices and openings in the rock. Similar to a clamping wedge, it is used for rock climbing as intermediate protection or for building a stand .
Construction and shape
It is a semicircular metal wedge in the shape of a segment of a circle with a pyramid-shaped tip on the inside of the segment of a circle. At one end of the circular segment, a flat belt is rotatably suspended in an axle. Smaller tricams have a recess on the outside of the circle segment, and larger tricams have several guide axes. The flat strip can be inserted into the recess or onto the guide axes and guided to the other end of the circle segment. At the end of the flat belt there is a loop for attaching a snap hook . A nominal load is usually specified on the loop, which is usually between 6 and 22 kN. Large tricams are generally composed of sheet metal parts as hollow bodies to reduce weight.
Operation and use
Tricams are mainly used in alpine or sport climbing . In doing so, they are clamped into existing structures in the rock, which run in the main load direction. Structures that run forward are mostly found in round cavities in the limestone, furthermore in cracks in the rock and between large boulders.
The main direction of loading points downwards in the case of intermediate securing as the direction of fall, also in the construction of a stand ; there, however, it can also point upwards if the tricam is used to brace the stance downwards. Lateral main directions of loading are also possible if the tricam is braced with other mobile securing material.
According to a first and most common type of use, the tricam is inserted into the opening in the folded-down state, that is, with the axis of rotation of the flat belt forward, and clamped against unintentional slipping out by a tensile load on the flat belt. This creates three contact points with the rock: two on the outer edges of the circle segment and the opposite tip. Each additional tensile load exerts a torque on the metal part of the tricam, which increases the jamming effect. This type of use is particularly suitable for holes, such as those often found in limestone. But it can also be used in cracks and spaces.
Furthermore, according to a second type of use, the tricam can be used like a large clamping wedge. For this purpose, it is inserted with the axis of rotation of the flat belt backwards from a wider point into a crack or gap in the rock that narrows in the main load direction and clamped. In this position, it is tightened to prevent it from accidentally slipping out. This type of use is mostly suitable for cracks and gaps. It is usually difficult to use in holes.
The Tricam can be removed after use. The first time it is used, it is pushed forward and removed from the ribbon while avoiding tension. In the second type of use, it is removed from the crack or gap against the main load direction. In both cases, a wedge remover can be used to loosen a stuck tricam.
Tricams hold tensile loads and falls in the intended main load direction. A load in another direction may tear the tricam out of its position or loosen it so that it can be wiggled out of its position.
In order to be able to cover a wide range of clamping widths, climbers usually carry several tricams of different sizes and other clamping devices, e.g. B. Chocks , Hexcentrics or Friends with it. Tricams are primarily used for holes and medium to large cracks and spaces. Their advantages are that they can be used for holes that are unsuitable for other clamping devices such as Rocks or Hexentrics . Furthermore, compared to Friends, they have a simple, robust construction and a significantly lower price.