Conical cam

Abstract

A conical cam rotates through a greater angle than a conventional planar cam in constricted spaces providing a greater range of movement. A climbing device for obtaining a secure removable fixing in a crevice utilises one or more conical cams to achieve an improved expansion range without loss of strength and without additional weight or complexity.

Description

FIELD OF THE INVENTION[0001]This invention relates to cams and camming devices and in particular to camming devices useful for climbing.CROSS-REFERENCE TO RELATED APPLICATIONS[0002]A right of priority is claimed in relation to UK patent application no. 0600755.3, filing date 14 Jan. 2006.BACKGROUND OF THE INVENTION[0003]In many circumstances there arises a need to obtain a secure but readily removable fixing in parallel sided or similar fissures in rocks or other materials.[0004]A common example is that of rock climbers who require anchor points known as ‘belays’ or ‘running belays’ in order to protect themselves as they ascend their chosen route up a cliff.[0005]Many devices have been devised to achieve this end. Initially these consisted of simple metal wedges, typically incorporating a cable or nylon loop to facilitate the attachment of a rope or other equipment. Many shapes of metal wedge have been developed, including some in the shape of a cam which are able to offer some secu...

AI Technical Summary

Benefits of technology

[0020]The point at which conventional planar camming devices may no longer contract to fit within narrower openings is typically reached when the tips of the cams abut on the opposite walls of the opening (see FIG. 1). The conical nature of the present invention's camming member(s) permits the tip(s) of its cam(s) to extend perpendicularly away from the opening, thereby permitting a greater angle of rotation and an consequently reduced minimum opening size.

Problems solved by technology

If the cam angle is increased by modifying the shape of the cams, the expansion range is increased but the security is diminished.

The maximum size of the Friend device when fully expanded is limited by the size of the cams, more specifically by the distance between the tips of opposing cams (the part of each cam furthest from its axle) when the device is fully extended.

This separation can increase the expansion ratio, albeit to a relatively small degree and with a substantial weight penalty.

Such devices are necessarily wide and heavy due to the large number of cams involved, and they have not achieved commercial exploitation.

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