The present invention relates to an active camming device including a plurality of non-flat camming surfaces.
Climbers generally use clean protection devices for two distinct purposes. First, a clean protection device may be used as a form of safety protection for protecting a climber in the event of a fall and second, a clean protection device may intentionally be used to artificially support a climber's weight. Clean protection devices cam or wedge into a crack, hole, gap, orifice, taper, or recess in order to support an outward force. The area or surface within which the clean protection device supports the outward force is considered the protection surface. The protection surface can consist of natural materials such as rock or may consist of artificial materials such as concrete.
Clean protection devices are generally divided into active and passive categories. Passive protection devices include a single object, which contacts the protection surface to support an outward force. For example, a wedge is a passive protection device because it has a single head with a fixed shape. There are numerous types of passive protection devices including nuts, hexes, tri-cams, wedges, rocks, and chocks. Active protection devices include at least two movable objects that can move relative to one another to create a variety of shapes. For example, a slidable chock or slider nut is considered an active protection device because it includes two wedges that move relative to one another to wedge into various shaped crevices. When the two wedges of the slider nut are positioned adjacent to one another, the overall width of the protection device is significantly larger than if the two wedges are positioned on top of one another. The two wedges must make contact with the protection surface in order to actively wedge the device within the protection surface. A further subset of active protection devices is camming devices. These devices translate rotational displacement into linear displacement. Therefore, a slider chock would not be an active camming device because the two wedges simply slide relative to one another and do not rotate. Camming devices include two, three, and four cam lobe devices. The cam lobes on an active camming device are generally spring biased into an expanded position and are able to rotate or pivot about an axle to retract. In operation, at least one cam lobe on either side of the unit must make contact with the protection surface for the device to be able to actively support an outward force. Some active protection devices can also be used passively to support outward forces as well.
Active protection devices are generally preferable to passive protection devices because of their ability to cam into a variety of features. For example, a standard four-cam unit has a particular camming range that allows it to cam into features within a particular size range. Whereas, a passive protection device is limited to a single shape and can therefore only cam or wedge into features that conform to that particular shape. Unfortunately, the largest disadvantage of active protection devices is their considerable head width in relation to passive protection devices. Head width is defined as the maximum distance in the direction of the axle or axles longitudinal axis. Most camming devices contain three or four cam lobes. These cam lobes are typically driven by torsion springs on the axle. The large head width is primary made up of the cam lobes, the torsion springs, and the cable terminal or terminals.
Another advantage of camming devices over passive protection devices is their ability to protect awkward, flaring, and otherwise irregular cracks. This is a result of the cam lobes having independent action allowing them to adjust to the irregularities of the crack.
Traditional active camming devices include camming surfaces which are substantially flat. The camming surface is defined as the portion of the active camming device which engages the crack or recess. Generally, the camming surface is the outer part of one or more cam lobes. Substantially flat camming surfaces are designed to increase friction between the device and the recess within which it is engaged. Friction is necessary between the active camming device and the recess so that the device is not able to slide out. However, some irregularly shaped recesses may cause camming devices with flat camming surfaces to wobble due to a low number of contact points. This wobbling or instability could also cause an active camming device to fail or release from a placement. For at least these reasons, there is a need in the industry for a more stable camming surface design that is applicable to all camming devices.
The present invention relates to an active camming device including a plurality of non-flat camming surfaces. In accordance with the present invention, the opposing camming surfaces are shaped to include substantially concave and convex surfaces respectively. In one embodiment, each individual cam lobe is shaped in a substantially concave or convex manner to form a cam surface. In another embodiment, a plurality of cam lobes disposed on a single side of a device, are shaped to provide a combined substantially concave or convex surface. The convex surface or surfaces are always disposed opposite of the concave surface or surfaces to provide an increased stability in uneven recesses. Non-flat camming surfaces increase the stability of a camming device in irregular recesses by increasing the number of connection points between the device and the recess.
The embodiments described above may also be combined in any manner to create additional embodiments. The foregoing and other features, utilities, and advantages of the invention will be apparent from the following detailed description of the invention with reference to the accompanying drawings.
The accompanying drawings illustrate various embodiments of the present invention and are a part of the specification. The illustrated embodiments are merely examples of the present invention and do not limit the scope of the invention.
Reference will now be made to the drawings to describe presently preferred embodiments of the invention. It is to be understood that the drawings are diagrammatic and schematic representations of the presently preferred embodiments, and are not limiting of the present invention, nor are they necessarily drawn to scale.
The present invention relates to an active camming device including a plurality of non-flat camming surfaces. In accordance with the present invention, the opposing camming surfaces are shaped to include substantially concave and convex surfaces respectively. In one embodiment, each individual cam lobe is shaped in a substantially concave or convex manner to form a cam surface. In another embodiment, a plurality of cam lobes disposed on a single side of a device, are shaped to provide a combined substantially concave or convex surface. The convex surface or surfaces are always disposed opposite of the concave surface or surfaces to provide an increased stability in uneven recesses. Non-flat camming surfaces increase the stability of a camming device in irregular recesses by increasing the number of connection points between the device and the recess. Also, while embodiments of the present invention are described in the context of an active camming device with non-flat camming surfaces, it will be appreciated that the teachings of the present invention are applicable to other applications as well.
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In the illustrated embodiment, the geometry of the first and second cam surfaces 110, 105 causes the active protection device 100 to contact a recess in at least three locations regardless of the shape of the recess. The stability and reliability of an active cam placement often depends on the number of contact points between the active camming device and the recess. By ensuring that the active camming device 100 always contacts a recess in at least three locations, a minimum level of stability and reliability is created. This increased stability in a recess or orifice will be described in more detailed with reference to
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Alternatively, the outer cam lobes 420, 405 could be modified to create a combined upper concave cam surface and the inner cam lobes 415, 410 could be modified to create a combined lower convex cam surface. In addition, by only curving a portion of an existing cam surface, the advantages of opposing concave and convex surfaces are achieved without losing all of the frictional properties of a flat camming surface. Various degrees of flatness and curvature can be incorporated into a camming surface to produce different properties.
It should also be noted that many of the advantages of the present invention can be achieved with only one convex for concave cam surface. For example, on a two cam lobe active camming device, one cam lobe could be traditionally flat while the other is shaped to create a concave cam surface. This single concave or convex cam surface configuration is also applicable to active camming devices with more than two cam lobes.
While this invention has been described with reference to certain specific embodiments and examples, it will be recognized by those skilled in the art that many variations are possible without departing from the scope and spirit of this invention. For example, the teachings of one embodiment may be combined with the teachings of another and remain consistent with the scope and spirit of this invention. The invention, as defined by the claims, is intended to cover all changes and modifications of the invention which do not depart from the spirit of the invention. The words “including” and “having,” as used in the specification, including the claims, shall have the same meaning as the word “comprising.”
This application claims priority to U.S. Provisional Application Ser. No. 60/538,491 filed Jan. 22, 2004, entitled “ACTIVE CAMMING SURFACE”.
Number | Date | Country | |
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60538491 | Jan 2004 | US |