Inventor Tony Christianson came up with the idea for a double axle cam and teamed up with Chouinard Equipment (now Black Diamond Equipment) to produce the Camalot . He filed a patent (US 4,643,377) on 26th September 1985. This reached the end of its 20 year term on 26th September 2005. Protection in Europe was sought in Germany, France, Great Britain and Italy with an EPO (EP 0 223 964 B1) filing date of 25th September 1986 (one day before the 12 month Paris Convention time limit). The expiry of his European protection occurred 20 years from the EPO filing date – 25th September 2006.
Extract from Christianson’s Camalot patent (US 4,643,377)
Considering the popularity of the Camalot it is surprising that other manufacturers have not taken advantage of the now unprotected dual axle design. It has been 2-3 years since the protection ended and presumably the development of a Camalot copy would not take longer than 2-3 years. Either manufacturers are not aware that the patents have expired or have, for one reason or another, decided not to pursue the dual axle option.
An early Camalot prototype, image from .