A Tricam is a type of climbing protection equipment.[1] The most versatile nut, the Tri-cam, was invented by Greg Lowe in 1973, and came to market in 1981.
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It is a passive or active device consisting of a shaped aluminium piece attached to a length of webbing tape or wire cable. The device is designed to be inserted into a crack so that pulling on the tape or wire makes the piece cam outward against the sides of the crack, gripping the rock tighter. This camming action is achieved by the position of the pointed fulcrum of the piece relative to the attachment of the tape or wire. As the webbing or wire is pulled, the downward force is pivoted onto the point, which can bite into soft rock or ice and increases the holding power of the tricam. [2]
Tricams are generally not as easy to place or remove as spring-loaded camming devices (SLCDs) but are much cheaper, lighter, and have some of the highest breaking strengths out of all rock climbing protection devices. Unlike SLCDs they are less likely to fail in the alpine environment as they have no moving parts to freeze, making them an excellent choice for a mountaineer's rack. They typically work best on sandstone or limestone as the fulcrum is more likely to bite into the soft rock.
They can also be used passively as nuts.[2]
Placing a tricam is relatively simple but takes practice to achieve proficiency. Care must be taken so that the tricam does not loosen while climbing above its placement due to rope drag. Typically, this additional safety is provided by clipping a longer sling to the tricam. In addition to this weakness tricams can also exhibit welding characteristics after being subjected to a hard fall making them harder to clean and more likely to be left behind.
Tricams are available in a range of sizes to suit cracks from 10–140 mm wide.[2] They are especially useful in horizontal cracks, quarry drill holes, and limestone pockets, where they may be the only type of protection that works. The smallest size can also work well in old piton scars.
As manufactured they come in size numbers 0.125 to 7, with strength 2–22 kN, width 10–140 mm, and weight 9–264 g.[2]