This invention concerns snowshoes, particularly snowshoes of molded plastic or composite material, and the invention encompasses a molded snowshoe with improved ability to adapt to uneven terrain.
Traction and stability on a varied terrain are valuable attributes for a snowshoe. One way to allow enhanced traction and stability is to provide a snowshoe structure which can adapt to various surface contours to effect better contact with the surface, and thus enhanced traction and stability. This invention provides a structure with improved ability to adapt to and make contact with the snow or ice surface on which the snowshoe is used.
Typical snowshoes provide flotation, traction and stability by the incorporation of flotation means (primarily a deck), traction means (cleats or rails), and a means to attach the user's foot to a relatively rigid structure (a boot binding).
The traditional frame based snowshoe has a peripheral framed structure that is essentially rigid. This is required to suspend and support the traditional flotation surfaces that consist of flexible members such as rawhide strips, coated fabrics or thin plastic sheets. Traction elements are attached to the underside of this construction for improved traction on ice and snow surfaces. A binding of some type is attached to the structure to receive the user's foot. The traditional framed snowshoe construction thus teaches the need for a rigid frame surrounding the periphery of the snowshoe, and a flexible decking material suspended within the frame. The flexible decking is inherently too flexible to bear the flotation loads of the snowshoe without the support of the peripheral frame.
It can be advantageous with such a construction to allow the traction elements attached to the snowshoe structure to conform to the contours of the snow and ice surface by providing some level of relative flexibility or suspension from the generally rigid structure of the snowshoe. The flexible decking snowshoe suspends some traction elements on the deck, and suspends the binding (with toe cleat) somewhat, and thus adapts to some extent to the terrain. Other prior approaches using this concept include the use of various suspension systems such as in K2 Snowshoes U.S. Pat. No. 6,898,874, which provides adaptation to side terrain. There have been other approaches for suspending the snowshoe binding and the traction elements attached to the underside of the snowshoe bindings, which allow some degree of relative motion or flexibility between the overall snowshoe structure and the binding with its attached traction means.
More recently, constructions of snowshoes have been developed that consist of flotation surfaces formed of materials such as injection molded plastic, of a thickness and stiffness such as not to require peripheral frames to help resist and support the flotation loads associated with snowshoeing. One such prior art example can be found in the MSR Denali model snowshoe made of a molded one piece surface comprising the flotation surface of the snowshoe. Additional structure is provided in the form of two steel rails running longitudinally along the lower side of the molded decking surface, which also serve as traction elements. This prior art teaches the importance of structural rigidity through the combination of the structure of the longitudinal metal rails, along with structural channels molded into the decking structure of the snowshoe. See, for example, MSR U.S. Pat. Nos. 5,469,643, 5,517,773 and 5,921,007.
In the described MSR snowshoe, the binding of the snowshoe was attached to the longitudinal traction rails in a pivoting fashion. A certain degree of structural flexibility of the overall structure is obtained by this arrangement. However, the structural rigidity of this construction is also somewhat limiting on the degree to which the structure can conform to the underlying contours. Further, the need to use one material for the entire deck surface for such constructions can be a limitation in the selection of materials to meet the various requirements of the snowshoe structure.
The above are examples of ways in which the prior art has achieved the required flotation and structure required of a snowshoe combined with contact and traction with the underlying terrain surface.
The prior art also discloses a compound deck snowshoe, with an additional piece of deck structure or “tail extender” that can be added or taken off the snowshoe body by the user, as a means to alter the degree of flotation of the snowshoe, as in U.S. Pat. Nos. 5,517,773 and 6,195,919; see also U.S. Pat. Nos. 6,006,453 and 6,226,899. While such prior art does disclose a deck comprised of two or more pieces, it does not teach any method for substantially affecting the overall structural flexibility of the snowshoe structure, for adaptation to terrain. Further, the loads that can be imparted into the second decking section in U.S. Pat. No. 6,195,919 are limited by the absence of any substantial structural member spanning the mating region.
There is a need for a molded or composite snowshoe that has a deck rigidity sufficient for the needed flotation while also affording a torsional (warping) flexibility that allows the traction elements or cleats on the snowshoe bottom to contact uneven terrain.
A molded snowshoe construction in accordance with the invention includes a decking surface constructed of a material and of such thickness that support from a peripheral frame is not needed. A typical such snowshoe decking can be formed of molded plastic materials of approximately 3 mm thickness, or molded fiber reinforced composite of somewhat lesser thickness.
The molded snowshoe of the invention is constructed in a way so as to allow the cleats or traction elements of the snowshoe to contact the underlying terrain surface contours even when the surface is uneven, greatly improving traction. This is achieved by improving the structural flexibility of the snowshoe by forming the deck of the molded snowshoe in two or more separate pieces connected together. These pieces are molded of materials and of a thickness such they are able to bear the flotation loads required by the snowshoe. Structural integrity of the snowshoe is obtained by the use of elongated structural members, such as metal rails on the snowshoe bottom, which extend continuously through a joint between the deck segments, but the design affords torsional flexibility of the snowshoe.
Preferably the multi-section deck structure is formed with a fore deck section and an aft deck section. The joint preferably is at two locations, both being narrow outer rims at left and right, adjacent to a large central opening in which the snowshoe binding is suspended. The sections are joined in these narrow regions in a way that allows for torsional flexibility of the snowshoe, improving flexibility to accommodate deformation so that the cleats or traction elements at the bottom of the snowshoe can better adapt to uneven terrain, to improve traction. The positioning of the joints is designed to allow conforming deformation in a way that will optimally adapt to terrain.
In a preferred embodiment two main longitudinal structural elements span the region where the two deck sections meet. These structural elements advantageously comprise metal rails extending through most of the length of the snowshoe and serving also as traction elements on the underside of the snowshoe. Further, the boot binding can be supported by the metal rails, which applies the load from the user directly to these elongated metal structural elements that also preferably serve as traction rails.
The compound molded deck structure of the invention has the further advantage that the fore deck and aft deck sections can be formed of materials with different properties, such that each section, and portions within each section (via thickness variation), can be tailored to achieve a degree of local flexibility which serves the objective of the overall structure.
Accordingly, it is among the objects of this invention to achieve in a molded snowshoe a better ability to adapt to uneven terrain and to make good traction with the terrain, while still maintaining the strength, needed flotation and structural integrity of a molded snowshoe. These and other objects, advantages and features of the invention will be apparent from the following description of a preferred embodiment, considered along with the accompanying drawings.
In this form of the invention the snowshoe body has a large central opening 11 for a crampon/boot binding assembly, in this case a boot binding that includes a heel support area (as opposed to snowshoes that allow the boot heel to rest on a rear deck area, such as in
As the drawings indicate, the joint formed by the connections 16 and 18 preferably is behind a snowshoe nose portion 24 and generally in a region where a snowshoe binding (not shown) will be supported for pitch pivoting movement.
The joints 16, 18 provide for the torsional flexibility of the snowshoe in combination with the flexibility of the snowshoe molded deck sections themselves, a function of material and thickness and any reinforcing patterns molded into the deck. The two deck sections can be of different materials, not only for torsional flexibility or rigidity but to provide one section with higher strength or toughness requirements than the other. Properties can be tailored; colors can be different.
The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.