Patent Application
20090230268
This invention relates to climbing aids and is particularly though not necessarily exclusively concerned to climbing aids for rock climbing and the like.
Modern rock climbing is a surprisingly safe sport thanks to the well thought through system of protection developed since the emergence of the sport in the 1960s. A climber moving up a rock face is tied into one end of a rope, the other end of which is handled by a climbing partner from a safe stance. The climber protects himself by clipping the rope into intermediate anchoring points as he proceeds up the route. On most climbing routes one has to rely on artificial anchoring points. In the past, use of semi-permanent anchors such as pitons and bolts was common. However, those practices led to irreversible degradation of rock faces, and were consequently almost entirely abandoned by the climbing community. In the modern “traditional” rock climbing, pieces of protection are placed into rock that can be easily removed afterwards and that cause no damage to the rock. Pieces of protection can be divided into passive and active. The most popular pieces of active protection are broadly referred to as SLCDs, or “spring-loaded camming devices”, because of the key element of structure—spring biased cams of a special shape. As first introduced in U.S. Pat. No. 4,184,657, SLCD operates by converting a traction force moving out of the crack into a force applied against the walls of the crack through the use of cams, such that the friction created between the cams and crack walls counteracts the force pulling on the device. Thus, however large the applied pull is, there results enough friction to prevent SLCD from getting pulled out (as long as the placement is sound, and the rock is good). Typically, an SLCD has three or four cams, two of them engaging one wall of the crack and the rest engaging the other wall. When SLCD is placed, the cams behave semi-independently, adjusting to the shape of a particular crack.
One of the most important features of SLCDs is the shape of the cams. The cams have an arcuate surface in the shape of logarithmic spiral, characterized by the property that the angle between the tangent and radial line at a point is constant. The radius of the spiral increases between two sizes, making it possible to place an SLCD of a particular nominal size into different cracks having a range of widths. But independently of width of the crack, the SLCD will distribute forces at a constant angle to the walls of the crack, determined by the angle chosen for the logarithmic spiral of the cams.
Advent of SLCDs created a revolution in traditional climbing, by making many climbs much easier to protect, and making climbing generally safer. However, what may be considered a common weakness of all the existing types of gear used in traditional climbing is that it must be placed into cracks or suitably shaped recesses in the rock. Generally speaking, absence of cracks renders a rock face “unprotectable”, such that it cannot be climbed safely. The only way to protect such a climb would be to place bolts or pitons. The present invention presents a drastically novel piece of protection that does not require a crack for successful placement; instead it is placed onto rock protrusions of suitable shapes.
Certain types of rock—such as limestone, sandstone, and tufas—rarely or never form cracks. They do, however, often provide protrusions that rock climbers “pinch” with their fingers. The present invention can be placed over some of the same protrusions to provide an anchoring point.
This invention relies on the cams of the same shape, and on the same principle of transformation of the force of pull into force of friction that are used in SLCDs.
The current invention can be contrasted to other conceivable clamping devices. First, consider a device (referred to below as “device A”) that uses powerful springs to create sufficient forces of friction. Typical requirement for a not-too-small SLCD is that it should be able to support a force of pull of 14 kN (roughly 20 times the weight of a 70 kg person). To create sufficient forces of friction the springs of device A would have to create forces on the order of 100 kN. These springs would obviously be impossible to operate directly by hand. Any mechanistic ways to operate such springs would add extra weight and bulk, and would be inconvenient in a climbing situation. Second, consider a device (“device B”) that uses a sort of screw driven cams to squeeze a rock protrusion to provide necessary forces of friction. Device B will be impossible to operate with one hand, because until its width is properly adjusted it cannot support itself on the rock. But being able to operate climbing gear with one hand is extremely important for a climber because he has to use one hand to support himself on the rock. Another problem with device B is that it would take a substantial amount of time to adjust its width, because that would require multiple turns of a screw. But any extra time spent on the rock drains a climber's energy that may be required later on the climb.
A “device C” may be similar to pole climbing devices of U.S. Pat. Nos. 4,407,391 and 4,595,078. As can be seen in
According to the present invention the anchoring device in
Each cam 1 is actuated by a length of rigid wire 7a, which is bent approximately perpendicular to its length to pass through a hole 6 in the cam, and which is free to pivot within the hole. The free end of the wire 7a is further bent to prevent it from slipping through the hole 6. The opposite ends of the rigid wires 7a from the cams located on the same axle 2 are crimped with malleable connectors 7b to opposite ends of a flexible cable 7c. The flexible cable 7c passes through two holes 8 in the frame 3, and is attached to the trigger 10 by looping through two holes 9 at one end of the trigger. The main support cable 11 passes through a hole 10a in the trigger 10, so that when the trigger is manually engaged it can slide along the cable 11. When the trigger is pulled, the pulling force and motion are transmitted through cables 7c and wires 7a to cams 1 to actuate them against their biasing springs 5; the actuated position of the cams will be referred to as “retracted”.
It is suggested that the main support cable 11 is made of stainless steel enclosed in a layer of flexible transparent plastic. In this case the cable will be comfortable for a climber to handle, will have a desired flexibility, and will be easy to inspect for signs of damage. The main support cable 11 passes through a hole 14 in the frame 3 and is connected by brazing to a conical wedge 12. The hole 14 is shaped so as to prevent the wedge 12 from pulling through when a pull is applied to the cable 11. The other end of the main support cable 11 is looped back approximately 180 degrees and connected with a swaged connector 13 to a point on the cable so as to form a loop to which a climbing rope may be attached by using a carabiner or other similar device. The loop also forms the means for engaging a human thumb so as to permit operation of the cams 1 by the opposing motion of the thumb and fingers with the fingers engaging the trigger 10.
