Abstract:
A camming device is provided that has a superior range of operation, is lighter and has lower internal compressive forces. The improvement is a result of using a composition having a co-efficient of friction ranging between 0.35-0.55 affixed to the contact area, for example, a semi-metallic composition. An improved method of fall protection is also provided, as is a method of manufacture.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. provisional patent application Ser. No. 60/672569, filed 18 Feb., 2005, entitled Camming Device for Climbing and Use Thereof. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention is related to devices to assist rock and mountain climbers. Specifically, this invention is a climbing cam that has a superior range as a result of long-lasting high friction material on the face of the cam and low weight “rope” stem.  
       BACKGROUND OF THE INVENTION  
       [0003]     Mountain climbing is a sport of limits. Rock climbers are relentlessly striving to push these limits by enduring personal physical pain, improving technical climbing abilities and inventing innovative technical gear. Lowering weight and increasing strength of climbing gear are the fundamental improvements that are required to extend the limits of climbable routes. Fall protection is the key aspect to this. Fall protection is what a climber uses to secure himself/herself to the rock face while climbing. In the event of a fall, the “fall protection” will stop the climber falling to their death. Fall protection requires a delicate balance between strength requirements and weight conservation.  
         [0004]     A climbing camming device (cam or friend) is one type of device used as fall protection by mountain climbers. Primarily used for crack climbing, the cam is inserted into a crack and the safety rope is fixed to the stem loop. Friction from the rock/aluminum lobe interface and the outward normal force generated by the unique cam lobe shape holds the camming device in the crack when loaded by a fall. Camming devices have revolutionized rock climbing because climbing routes with parallel crack systems can now be protected. Also, unlike pitons or other forms of permanent protection, camming devices do not damage the rock and are easily placed and removed.  
         [0005]     Camming devices range in size and consist of two to four aluminum spring-loaded cams (lobes) with a logarithmic spiral contact shape. These cams are mounted onto a stainless steel axle and connected to a 3/16″ 302 stainless steel aircraft cable stem. The climbing rope is fixed to the stem with standard nylon webbing and when weighted the downward force on the stem forces the cams to spread and hold into the rock.  
         [0006]     When traveling to and from the climbing site, and while on a climb, a climber must carry a full range of camming devices in order to accommodate various crack sizes. For this reason, it is necessary to consider the weight of the rack of camming devices. Various approaches have been taken to reduce the weight. Firstly, aluminum is used as much as possible as it is lighter than steel. Second, the weight has been further reduced by introducing apertures into the camming devices. As the number of axles used also affects the weight of a camming device, weight can be reduced by using single axle camming devices, rather than the heavier double axle camming devices. These approaches reduce the weight of each camming devices, and therefore, the weight of the rack.  
         [0007]     An alternative approach to lightening the weight of the rack, is to reduce the number of camming devices that needed to be carried. This can be done by increasing the range a given camming device. Expansion range is the maximum minus the minimum crevice size a camming device will tolerate. Double axle camming devices have more expansion range than single axle camming devices, hence fewer camming devices need to be carried. However, this gain may be offset by the increased weight of the double axle camming devices over that of the single axle camming devices.  
         [0008]     The problem for climbers is how to reduce the weight required for climbing while remaining within an acceptable safety margin, based on fit of the camming device in the crack and strength of the camming device. It is an object of the present invention to overcome the deficiencies of the prior art.  
       SUMMARY OF THE INVENTION  
       [0009]     An improved camming device is provided that has a superior range of operation, is lighter and has lower internal compressive forces. A camming device is for use as protection in cracks during rock climbing, and comprises at least one pair of lobes, one axle per pair of lobes, a stem, a loop and a release mechanism. The lobes comprise: a face having a contact area; an inside edge; an apical end; and a basal end, to define an inner surface and an outer surface. The improvement comprises a semi-metallic composition comprising at least one metal affixed to the contact area.  
         [0010]     The composition may comprise metals selected from the group consisting of aluminum, brass, bronze and copper. The composition may be semi-metallic. By semi-metallic it is meant that a portion, ranging from a trace to a substantial amount of the composition is metal, but that it is only one component of the composition, which may comprise one or more other components.  
         [0011]     In another aspect of the invention the composition is housed in a recess in the face.  
         [0012]     In another aspect of the invention the recess extends substantially from the apical end to the basal end.  
         [0013]     In another aspect of the invention the recess terminates in a tab at the apical end and a tab at the basal end.  
         [0014]     In another aspect of the invention the composition has a co-efficient of friction in the range of 0.35-0.55.  
         [0015]     In another aspect of the invention the co-efficient of friction is in the range of 0.45-0.55.  
         [0016]     In another aspect of the invention the co-efficient of friction is about 0.46.  
         [0017]     In another aspect of the invention the composition is affixed with an adhesive.  
         [0018]     In another aspect of the invention the semi-metallic composition is additionally mechanically affixed.  
         [0019]     In another aspect of the invention, an improved camming device is provided that has a superior range of operation, is lighter and has lower internal compressive forces. A camming device is for use as protection in cracks during rock climbing, and comprises at least one pair of lobes, one axle per pair of lobes, a stem, a loop and a release mechanism. The lobes comprise: a face having a contact area; an inside edge; an apical end; and a basal end, to define an inner surface and an outer surface. The improvement comprises a semi-a composition having a co-efficient of friction ranging between 0.35-0.55 affixed to the contact area.  
         [0020]     In another aspect of the invention the composition is housed in a recess in the face.  
         [0021]     In another aspect of the invention the recess extends substantially from the apical end to the basal end  
         [0022]     In another aspect of the invention the recess terminates in a tab at the apical end and a tab at the basal end.  
         [0023]     In another aspect of the invention the co-efficient of friction is in the range of 0.45-0.55.  
         [0024]     In another aspect of the invention the co-efficient of friction is about 0.46.  
         [0025]     In another aspect of the invention, the composition is comprised of a metal selected from the group consisting of aluminum, copper, bronze and brass.  
         [0026]     In another aspect of the invention, the composition is a semi-metallic composition.  
         [0027]     In another aspect of the invention the composition is affixed with an adhesive.  
         [0028]     In another aspect of the invention the composition is additionally mechanically affixed.  
         [0029]     In yet another aspect of the invention, an improved method of fall protection cracks during rock climbing is provided. The method comprises employing a camming device having a maximum range of about 0.9″-1.18″.  
         [0030]     In another aspect of the invention the maximum range is about 1.0″-1.18″.  
         [0031]     In another aspect of the invention the camming device has a co-efficient of friction on a contact area between 0.45 and 0.50.  
         [0032]     In another aspect of the invention the camming device has a co-efficient of friction of about 0.46.  
         [0033]     In another aspect of the invention, a rack of climbing cams is provided having five camming devices providing an operational range of approximately 4.0 inches.  
         [0034]     In another aspect of the invention, the rack comprises four camming devices providing an operational range of approximately 2.6 inches.  
         [0035]     In another aspect of the invention, the rack comprises three camming devices providing an operational range of approximately 1.7 inches.  
         [0036]     In another aspect of the invention, the camming device has two axles and two pairs of lobes.  
         [0037]     In another aspect of the invention, the loop comprises a composite cord.  
         [0038]     In another aspect of the invention, a method of manufacturing an improved a camming device is provided. The camming device is comprised of at least one pair of lobes, one axle per pair of lobes, a stem, a loop and a release mechanism, the lobes comprising: a face having a contact area; an inside edge; an apical end; and a basal end, to define an inner surface and an outer surface. The method comprises increasing the static co-efficient of friction on a contact area by affixing a semi-metallic composition to the contact area.  
         [0039]     In another aspect of the method, the semi-metallic composition is housed in a recess in the face.  
         [0040]     In another aspect of the method, the recess extends substantially from the apical end to the basal end.  
         [0041]     In another aspect of the method, the recess terminates in a tab at the apical end and a tab at the basal end.  
         [0042]     In another aspect of the method the semi-metallic composition has a co-efficient of friction is in the range of 0.35-0.55.  
         [0043]     In another aspect of the method the semi-metallic composition has a co-efficient of friction is in the range of 0.45-0.55.  
         [0044]     In another aspect of the method the semi-metallic composition has a co-efficient of friction of about 0.46.  
         [0045]     In another aspect of the method the semi-metallic composition is affixed with an adhesive.  
         [0046]     In another aspect of the method the semi-metallic composition is additionally mechanically affixed.  
         [0047]     In another aspect of the invention, the method further comprises utilizing a suitably selected composite cord for manufacture of the loop.  
         [0048]     In another aspect of the invention, a method of manufacturing an improved a camming device is provided. The camming device is comprised of at least one pair of lobes, one axle per pair of lobes, a stem, a loop and a release mechanism, the lobes comprising: a face having a contact area; an inside edge; an apical end; and a basal end, to define an inner surface and an outer surface. The method comprises increasing the static co-efficient of friction on a contact area by affixing a composition having a co-efficient of friction in the range of 0.40-0.55 to the contact area.  
         [0049]     In another aspect of the method, the composition is housed in a recess in the face.  
         [0050]     In another aspect of the method, the recess extends substantially from the apical end to the basal end.  
         [0051]     In another aspect of the method, the recess terminates in a tab at the apical end and a tab at the basal end.  
         [0052]     In another aspect of the method the composition has a co-efficient of friction is in the range of 0.35-0.55.  
         [0053]     In another aspect of the method the composition has a co-efficient of friction is in the range of 0.45-0.55.  
         [0054]     In another aspect of the method the composition has a co-efficient of friction of about 0.46.  
         [0055]     In another aspect of the method the composition is affixed with an adhesive.  
         [0056]     In another aspect of the method the composition is additionally mechanically affixed.  
         [0057]     In another aspect of the invention, the method further comprises utilizing a suitably selected composite cord for manufacture of the loop. 
     
    
     FIGURES  
       [0058]      FIG. 1  is a perspective view of a camming device in accordance with an embodiment of the invention.  
         [0059]      FIG. 2  is an exploded view of the camming device of  FIG. 1 .  
         [0060]      FIG. 3A  and B are drawings of the radius of the extended and contracted camming device of  FIG. 1 .  
         [0061]      FIG. 4  is a perspective view of a lobe of the camming device of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0062]     A camming device for climbing, generally referred to as  10 , is shown in  FIG. 1 . The camming device  10  has two cams  12  in parallel relation to each other, each comprising two lobes, an inner lobe  14  and an outer lobe  16 , for engaging a crack when actuated. The lobes  14 ,  16  are aluminum. The two cams  12  are rotatably mounted on a stainless steel axle  18 , by means of a bore  20 , such that inner lobes  14  oppose one another and the outer lobes  16  oppose one another as shown in  FIG. 2 . The lobes  14 ,  16  define a radius that expands as the camming device  12  is actuated, as shown in  FIG. 3A  and B. Each lobe  14 ,  16  is generally triangular and has a face  22 , and an inside edge  24  terminating at an apical end  26 , and a basal end  28  opposing the apical end  26  as shown in  FIG. 4 . An inner surface  30  and outer surface  32  are defined by the face  22 , edge  24  and ends  26 ,  28 . The face  22  has a logarithmic contact shape, with the contact area  34  comprising a semi-metallic composition. The semi-metallic composition is brake pad material, having a static coefficient of friction of about 0.46 when contacted with rock. The semi-metallic composition on the contact area  34  is affixed using adhesive and is housed in a recess  36  of the lobe  14 ,  16  with tabs  38 ,  40  extending from the apical end  26  of the lobe  14 ,  16  and the basal end  28 , of the lobe  14 ,  16  as shown in  FIG. 4 . The semi-metallic composition increases holding power, allows for an increased operational range and lowers internal compressive forces. A stop  42  subtends the recess  36  in the vicinity of the basal end  28  and protrudes from the inner surface  30  of the outer lobe  16  and the outer surface  32  of the inner lobe  14 , such that the stop  42  of one lobe  14  abuts the basal end  28  of the other lobe  16 , when the camming device  10  is fully retracted. In this position, the camming device  10  may function as passive protection.  
         [0063]     The axle  18  is retained in the bore  20  of the lobes  14 ,  16 , by means of a hub  44  on either end  46  of the axle  18 . Between the pairs of cams  12 , a stem  48  comprising a composite cord made of Parallay™ construction HMPE fibre is rotatably mounted on the axle  18 . A washer  47  is located on the axle  18  between the stem  48  and each inner lobe  14 . A loop  50  is affixed to a distal end  52  of the stem  48  by splicing. A guide,  51 , is rotatably mounted on the axle  18  and accepts the stem  48 .  
         [0064]     A release mechanism  56  is slidably mounted on the stem  48  by a plate  58  with a centrally located release bore  60 , through which the stem  48  slides. Adjacent the release bore  60  on either side of the release bore  60  are a pair of bores  64  through which a resilient member, such as a cable  66  is threaded. The cable  66  is aligned such that the distance between the two lobes  14 ,  16  and the plate  58  is the same. Each lobe  14 ,  16  has an aperture  54  to accept the cable  66 . The aperture  54  on the outer lobe  16  is on the outer surface  32  and the aperture  54  on the inner lobe  14  is also on the outer surface  32 . The cable  66  of the release mechanism  56  is rotatably within the aperture  54 .  
         [0065]     The lobes  14 ,  16  are biased from one another in a cam  12  by biasing means, such as a spring  68 . Hence, when downward pressure is exerted on the camming device  10 , the cams  12  spring open into an actuated position, in which the face  22  with its contacting surface  34 , engages a crack by abutting opposing rock walls of the crack. When the climber wants to release the camming device  10  from the crack, he pulls the plate  58  of the release mechanism  56  away from the rock while pushing the stem  48  in towards the rock, and the camming device  10  is released. The camming device  10  is then returned to a rack of camming devices.  
       EXAMPLE 1  
       [0066]     Detailed friction testing of five advanced composite friction materials against 8 different types of rock, laboratory testing of twelve different two-part adhesives (including expoxies, acrylics and urethanes) for break away and internal strength and extensive research into new market products, in terms of cords, heat shrink tubing and metal based putties was carried out. This led to inventing a camming device with an 81.3% increase in the standard working range and a 34.5% reduction in stem weight.  
                                                       TABLE 1                           Friction Material Testing                Co-Efficient of Friction (μ)           (Frictional Force/Normal Force)                        AFT-   AFT-   Al-   F4-3-       Friction Materials   HF-61   9010   1006   200   6106   252               Rock Types                               Black Sandstone   0.38   0.58   0.45   0.35   0.48   0.38       Green Sandstone   0.48   0.41   0.62   0.53   0.53   0.64       Yellow Quartzite   0.59   0.62   0.62   0.55   0.52   0.55       Pink Quartzite   0.63   0.61   0.66   0.06   0.42   0.58       Gneiss   0.53   0.66   0.56   0.47   0.42   0.46       Basalt   0.33   0.55   0.33   0.39   0.34   0.45       Limestone   0.43   0.55   0.27   0.39   0.36   0.23       White Granite   0.67   0.67   0.51   0.54   0.45   0.43       Average Co-Efficient   0.51   0.58   0.50   0.41   0.44   0.47       of Friction       Claimed Co-Efficient   0.61   0.46   0.52   0.42   0.31   0.41       of Friction       Corrected Test Values   0.36   0.41   0.35   0.29   0.31   0.33                  
 
         [0067]     The introduction of a high frictional co-efficient material to the rock/lobe interface increases the frictional forces of the cam. This increased holding power allows for an increased operational range and lower internal compressive forces. The operational ranges for a set of cams of the present invention is shown in Table 3. The increase in range for #6 Trango cam is 0.35″ this corresponds to a 49.3% increase. The increase in range for a #7 Trango cam=1.36″ which translates to an 81.3% increase.  
                                 TABLE 3                           Cam operational ranges                Cam   Trango   Improved cam                       #6   1.38 to 2.09   1.56 to 2.62           #7   1.89 to 2.64   2.60 to 3.96           #8   2.40 to 3.58                         *All in inches*             
 
         [0068]     The lobe shape of the cam is a logarithmic spiral defined as: 
 
r=e cθ 
        Where: r=radius of spiral 
            e=natural logarithm     c=coefficient defining how fast the spiral opens     θ=angle measured in radians    
               
 
         [0073]     The coefficient c, in equation (1) is limited by the coefficient of friction between the rock and the lobe interface. The claimed 0.42 coefficient of friction for material 9010 was used for the coefficient c in the lobe shape equation. Trango™ #7 (size 7 in Trango&#39;s range of cams) cam was used in the prototype model of the camming device, so the lobe size coefficient which factors the lobe equation to determine size is 0.515. This coefficient ensures that the vertical distance from the axle to the lobe surface is 1.00″, the distance for Trango cams.  FIGS. 3A  and B show an extended and a contracted cam lobe, demonstrating the range dimensions of the lobes for extended and contracted positions, respectively. The specified range of Trango&#39;s #7 Flex cam is 1.89″ to 2.64″ for a maximum range of about 0.75″. As shown in  FIGS. 3A  and B, the improved range is 2.60″ to 3.96″ for a maximum range of about 1.36″. The range of the improved camming devices of the present invention are shown relative to Trango camming devices. It can be seen from Table 3 that the range of the camming devices are significantly greater and hence, fewer camming devices are needed to cover the range of sizes. As would be known to one skilled in the art, the range is determined from a logarithmic equation, hence the percentage change in range will be exponential. For example, after detailing another cam of Trango&#39;s (the #6), the range increase was found to be 49.3%. This reduces the number of camming devices needed for a given rack.  
                                 TABLE 2                           Adhesives Evaluated            Product   Item   Batch           Number   Number   Number   Product Description               326/7649   32629/   2IP228B/   18,000 cP, amber, two-part no-mix           38402   3IV8700D   urethane methacrylate acrylic                   adhesive.       E-05CL   29299   3I29723A   1,900/2,800 cP, ultra clear, 5                   minute work life, two-part                   mercaptan epoxy.       U-05FL   29348   3AZ9618A   640/35,000 cP, off white, 5 minute                   work life, two-part polyurethane                   adhesive.                  
 
         [0074]     The foregoing is a description of an embodiment of the invention. As would be known to one skilled in the art, there can be variations in design of the camming device that do not change the scope of the invention. For example, the camming device can be a single cam or double cam device. The plate of the release mechanism may be machined or forged metal, or may be injection moulded and comprise a polymeric material. The stops may be contoured flush with the face of the lobe. The composite cord can be comprised of, for example, but limited to non-metallic advanced climbing or sailing materials and can be spliced, knotted, sewn, glued, or mechanically fastened to form a loop. The cord is the main tensile load bearing member of the camming device. Suitable materials and means of fastening would be known to one skilled in the art. A protective sheath can surround the loop in the stem. The semi-metallic composition may be affixed to the face of the lobe by mechanical means or by a combination of mechanical and adhesive means. Further, a ceramic composition might replace the semi-metallic composition, and this would alter the coefficient of friction accordingly. Still further, the semi-metallic composition can be replaced with soft metals, such as, but not limited to Aluminum 5052 and 3003, coppers, brasses, and bronzes, that have a co-efficient of friction of about 0.35 and higher. The coefficient of friction can range from about 0.35-0.55. These and other modifications are within the scope of the invention.