History
Vitaly Abalakov's invention of the Abalakov Cam was the first application to climbing of the principle of a constant-angle curved surface, with a cam shape based on the mathematical logarithmic spiral. Using a logarithmic spiral shape results in a constant angle between the cam and the rock at each contact point; this constant angle is designed to always provide the necessary friction to hold a cam in equilibrium. Designed so that a load produces a rotational force, the logarithmic cam shape allowed for a single device to fit in a range of crack sizes without a change in the loading pattern, making it predictable and stable.
In 1973 Greg Lowe filed for a patent for a spring-loaded version of the Abalakov Cam.
Modern SLCDs were invented by Ray Jardine in 1978 (US patent 4,184,657) and sold under the brand name of "Friends". Ray designed a spring-loaded opposing multiple cam unit with a more stable 13.75 degree camming angle and an innovative triggering mechanism. ("Friend" is now widely used by climbers to refer to SLCDs in general, but properly speaking it refers to the brand now manufactured by Wild Country.) Other popular brands include Black Diamond Camalots, Metolius Power Cams, DMM 4CUs, Trango FlexCams, and CCH Aliens.
Read more about this topic: Spring-loaded Camming Device
Famous quotes containing the word history:
“A poet’s object is not to tell what actually happened but what could or would happen either probably or inevitably.... For this reason poetry is something more scientific and serious than history, because poetry tends to give general truths while history gives particular facts.”
—Aristotle (384–323 B.C.)
“The history of all previous societies has been the history of class struggles.”
—Karl Marx (1818–1883)
“History takes time.... History makes memory.”
—Gertrude Stein (1874–1946)