MOUNTAINEERING CHOCK

Abstract: Artificial chockstone ("chock") for mountaineering having special but different convex shapes on a pair of opposing external working surfaces. Specifically, the outermost parts of the two opposing working surfaces each have convex shape in the form of a surface section of a cylinder, whereby the generating lines for the two cylinders are substantially perpendicular to each other. The chock is much less prone to accidental dislodgement from rock cracks than prior art chocks.

Description: MOUNTAINEERING CHOCK Techni a_l Field The present invention relates to an anchoring device of the type artificial chockstone for mountaineering, such chock- stones being generally known as "chocks". Background_Art Some typical examples of chocks for mountaineering and their advantages and modus- operandi are disclosed in e.g. US Patents Nos 3957237, 39-48-485, 39*46975, -40822*41, 4083521, and in MOUNTAIN Magazine 71 , p 11 (January/February 1980, Sheffield, England). The chocks are connected to a flexible extension (runner) in the form of a sling or wire and are used for ob¬ taining an anchor by jamming in rock cracks which are conver¬ gent or tapered in the direction of the expected load on the runner. A disadvantage with these and other known chocks is that they are easily dislodged by rope movements etc., parti- cularly from such cracks that besides being convergent in the direction of the load are also outwardly divergent ("flared cracks"), that is divergent in a direction being transverse to the direction of the load. Di C_lo_sure_o_f Inven i_on The invention relates to a mountaineering chock comprising of a rigid body having an aperture for accomσdating a runner, said rigid body having outer surface portions being shaped so that the chock, when placed with the runner pointing down- wards in a substantially vertical crack being slightly con¬ verging downwards and having two opposing plane walls which intersect each other along a horizontal line, will be suppor¬ ted by two .points at the first wall and by two points at the second wall, whereby the connecting straight (first) line between the two supporting points on the first wall is hori¬ zontal and whereby the projection, or the elongation thereof, on said first wall of the connecting straight (se between the two supporting points at the second wall forms a substantially perpendicular cross with the connecting (first) line at the first wall, whereby the chock may optionally also be supported along a substantial portion of, or the entire length of, one or both of said connecting lines. In a more generalized aspect, the invention relates to a mountaineering chock comprising of a rigid body having an aperture for accomodating a runner, a bottom surface, said runner aperture opening on said bottom surface, at least one pair of opposing external working surfaces tapering towards said bottom surface for engaging opposing walls of a tapered rock crack, the chock being characterized by the outermost parts of the two opposing working surfaces, each having a convex shape in the form of a surface section of a cylinder, whereby the generating lines for the two cylinders are sub¬ stantially perpendicular to each other. The chock according to the invention has been found to be much less prone to dislodgement from cracks, particularly flared cracks, than known chocks of corresponding simplicity and low cost of production. Furthermore, the weight and volume of the chock will usually be reduced in comparison to known chocks for corresponding crack-widths. These advantages have, as is evident from the above, been attained by pro¬ viding special convex shapes to a pair of opposing external working surfaces of the chock. Bjr ^ef^ 13ej3crύ.p_ti L on f_Drawing_s_ Fig. 1 is an isometric view of a chock embodiment according to the invention. Figs. 2-3 are vertical and horizontal cross-sections, respec- tively, of the chock in fig. 1 that illustrate how said chock is stably positioned in a vertical, flared and down¬ wards convergent crack. (The dashed line in fig. 2 indicates the cross-section shown in fig. 3 and vice versa). OMPI Figs. 4-8 are isometric views of further chock embodiments according to the invention. Fig. 9 is an isometric view of a variation of the chock in fig. 1. Fig. 10 is a plane side-view of a chock embodiment according to the invention that- has been developed from a Hexentric-nut Be_st__Mod £ _ c £^ y_ n £ u jl the. Invention Figs. 2-3 illustrate the positioning of the chock in fig. 1 in a vertical, flared and downwards convergent crack. It is seen that the chock is supported on the one (right) side alon a substantially horizontal line 1 and on the opposite (left) side along a substantially vertical line 2. This results in very stable placement of the chock in the crack. It is evident from the figures that this stable mode of support, which is along two substantially perpendicular lines, would be attained even if the angle of downward convergence (in fig. 2) and/or the angle of flare (in fig. 3) would be much different from those illustrated in said figures . The central location in the chock of the vertical support line 2 and the central location of the wire 3 on the dashed line in fig. 3 are- advantageous due to the lack of any ten¬ dency for outward-downward rotation of the chock when a down¬ ward force is applied to the wire. Such a tendency is, how¬ ever, common with conventional chocks. Preferably, the generating lines for one of the cylinders are substantially perpendicular to the general direction of the aperture, whereas the generating lines for the other cylinder are preferably substantially parallel to the general direction of the aperture. Fig. 4 is an isometric view of a further chock embodiment according to the invention, wherein- both working surfaces have convex shape in the form of a continuously arched or bent surface section of cylinders with no sharp edges, e.g. circular cylinders. This embodiment is particularly advan¬ tageous for small chocks. Such chocks are of necessity supported only along short lines which are then subjected to a correspondingly stronger pressure that might cause damage on sharp edges of the chocks. Fig. 5 is an isometric view of a still further chock embodi¬ ment, the working surfaces of which have characteristics from the chocks in both fig. 1 and fig. 4. Thus, one of the working surfaces consists of two non-parallel planes that intersect each other along a straight line and upon which the chock will be supported in the working position. Since this straight line is in the same plane as the load-bearing wire, there is no tendency for rotation of the chock, not even in strongly flared cracks . Fig. 6 and fig. 7 are isometric views of chock embodiments developed from the chock shown in fig. 4. In these embodiments depressions are formed in the midsection of at least one of the working surfaces. Such a depression is beneficial because the weight of the chock will be reduced. Another advantage with the depression is that the chock will be supported on two separately spaced sections on at least one of * the working surfaces, giving improved stability in rock cracks having convex walls or a rugged surface. In rock cracks having large protrusions on the sides thereof can such a protrusion even be saddled by the depression in the chock, and this inferring maximum stability. In one preferred embodiment of the chock, one or more of the working surfaces can in fact be saddle- shaped, so that a working surface in addition to being generally cylindrically convex is also concave in the midsec¬ tion with respect to a generating line perpendicular to the generating line of the cylindrical convexity. Fig. 8 illustrates an embodiment of the invention wherein the rigid body of the chock comprises of two opposing outer OMPI surface portions that are each provided with a centrally located elongate flange, whereby said two flanges are sub¬ stantially perpendicular to each other. If the flanges are removed, a conventional chock is obtained. Thus it is possibl to prepare a chock according to the invention simply by firml attaching flanges on the midsections of the workirig surfaces of a conventional chock. Fig. 9 is an isometric view of a variation of the chock in figs. 1-3- It has been provided with a groove along the support line 2. In the groove there has been inserted a rib 4 of hard rubber or similar resilient material which gives high friction against rock, and which has been fixed in the groove with an adhesive. Due to this modification the chock will stay safely in place even in strongly lared cracks . The rib has been narrowed in the middle so that the chock would generally be supported only at the end points of the line 2. This causes the chock to be more stably supported in those cracks that have convex walls or a rugged surface. The opposite support line 1 is shown straight in fig. 5, but at least the middle part of said line may preferably be some¬ what concave in the same or similar way as the rib 4 and for the same reason (there is however no need to provide the support line 1 with a friction-increasing material) . The chock will then be supported on four end sections only, resulting in a very stable placement. Fig. 10 is a plane side view of a further chock embodiment according to the invention. This chock is based on the so-called Hexentric nut disclosed in.US Patent No 3948485 (in particular fig. 2 therein), which is a type of chock that has three pairs of opposing tapered working surfaces. It is seen in fig. 10 that one (left) side of the chock has two ad¬ jacent working surfaces that are convex in a direction being parallel to the direction of the large lightening hole. The other (right) side of the chock has two adjacent working surfaces that are convex in a direction perpendicular to the direction of the lightening hole. The third (end-wise) pair of working surfaces can also be made to conform wi ' th the requirements of the invention, and this can be done by e.g. simply cutting away material from a conventional Hexentric. Conventional Hexentrics have short, wide working surfaces and are thus fairly unstable in flared cracks. The present inven¬ tion is therefore especially useful in connection with chocks of the Hexentric type. In the embodiments illustrated in figs. 1-9 only one pair of working surfaces is elaborated in each chock. However, it is preferable to make the other more narrow pair of working surfaces also tapered towards the bottom surface, thus obtaining a chock with unequal width between the working surfaces in each pair of opposing working surfaces, thus giving a chock that can be used in cracks of different widths. The other pair of tapered working surfaces may preferably also be designed with convex working surfaces according to the requirements of the present invention, but may alternatively be flat, or for example one surface may be convex and the other concave. It may be noted that all the embodiments shown in the drawings are symmetric with regard to one plane, and that the center- line of the aperture is part of this plane. (The aperture is thus divided in two equal parts by the symmetry plane). This symmetry gives maximum stability and it is thus preferred to make the chock symmetric with regard to such a plane. The inclination of the convexity of the two opposing working surfaces should preferably be such that when the chock is squeezed between two parallel planes the projection of each supporting line on the other plane should then divide the other supporting line in two parts of equal length. This means that each of the two lines in the perpendicular cross men¬ tioned on page 2, line 2, would be divided in two parts of essentially equal length when the. vertical crack converges only very slightly downwards. A further consequence of such an inclination of the convexity is that the chock has its maximum width at middle-height. The location of the aperture in the chocks illustrated in figs. 1-9, is indicated by a runner in the form of a single ■ wire that extends from the aperture in the longitudinal direc tion thereof. In most cases it is, however, preferred to have two parallel apertures through which a wire or sling is drawn and then joined to a loop, in the same way as is common with conventional chocks.

Claims: CLAIMS i. A mountaineering chock comprising a rigid body having an aperture for acco odating a runner, a bottom surface, said runner aperture opening on said bottom surface, at least one pair of opposing external working surfaces tapering towards said bottom surface for engaging opposing walls of a tapered rock crack, the chock being characte¬ rized by that the outermost parts of the two opposing working surfaces each have convex shape in the form of a surface section of a cylinder, whereby the generating lines for the two cylinders are substantially perpendicular to each other. 2. A mountaineering chock according to claim 1, characte¬ rized by the generating lines for one of the cylinders being substantially perpendicular to the general direction of the aperture. 3- A mountaineering chock according to claim 1, characte¬ rized by one or both of the working surfaces having a convex shape in the form of a continuously arched surface section of a cylinder. 4. A mountaineering chock according to claim 1, characte¬ rized by one or both of the working surfaces comprising two non-parallel planes that intersect each other along a straight line upon- which the chock will be supported in the working position. 5• A mountaineering chock according to claim 1, characte¬ rized by at least one of the working surfaces having a depression formed in the midsection of at least one of the working surfaces . -^0REA * OMPI 6. A mountaineering chock according to claim 5, characte¬ rized by the depression being in the form of an elongate groove. 7. A mountaineering chock according to claim 5, characte- rized by the depression being in the form of an open trans- • verse cylindrical hole that intersects both of the opposing working surfaces. 8. A mountaineering chock according to claim 5, characte¬ rized by that each of two opposing working surfaces having a depression in the midsection, formed so that the chock will be supported on two separate sections on each of two opposing working surfaces . 9. A mountaineering chock .according to claim 1, characte¬ rized by its having two pairs of opposing tapered working surfaces, wherein both pairs of opposing working surfaces fulfill the requirements in claim 1. 10. A mountaineering chock according to claim 1, characte¬ rized by its having three pairs of opposing tapered working surfaces, wherein at least two pairs of opposing-working surfaces fulfill the requirements in claim 1.

Inventors: MELLGARD INGEMAR, MELLGARD, INGEMAR
Applicants: MELLGARD INGEMAR, MELLGARD, INGEMAR
Application year: 1982
Main classification: A63B29
IPC codes: A63B29