Boots – shoes – and leggings – Boots and shoes – Occupational or athletic shoe
Reexamination Certificate
1997-12-22
2003-01-14
Kavanaugh, Ted (Department: 3728)
Boots, shoes, and leggings
Boots and shoes
Occupational or athletic shoe
C036S125000
Reexamination Certificate
active
06505423
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to winter outdoor gear, and more particularly to snowshoes.
BACKGROUND OF THE INVENTION
Snowshoes have long been used for walking on snow or ice covered terrain. A conventional snowshoe has a frame covered by a membrane, a front claw on the bottom front of the membrane, and straps to attach the snowshoe to a user's foot. The front claw is usually pivotally attached to the frame, beneath the ball of the user's foot. The user's weight at the ball of the foot causes the front claw to dig into the underlying terrain, providing friction that enables forward motion.
When used on level or uphill terrain, the snowshoe allows the user to walk about on snow or ice. Although the back of the snowshoe tends to drag along and skate or slide, the front claw permits forward motion because the user's center of gravity remains in a stable position.
It is known in the art to provide a flap-like cleat on the bottom of a snowshoe to improve its hill climbing ability. The cleat front hinges to the snowshoe, and the cleat “closes” against the snowshoe when pressed against the snow or ice. When the snowshoe is lifted, a spring urges the back of the cleat away from the snowshoe, into an “open” position preventing the snowshoe from sliding backward, thus promoting uphill use. However snow and ice debris can accumulate within the cleat, hampering snowshoe performance by preventing the cleat from fully closing.
Although suitable for level and uphill terrain use, conventional snowshoes do not perform well downhill because the rear of the snowshoe tends to skate or slide on the terrain surface. This skating prevents the user from maintaining a stable body position over the snowshoe. Commonly the user's weight is too far forward, causing the front claw to act as a fulcrum point about which the user pivots forward, usually just before falling to the ground. On the other hand, if the user's weight is shifted rearward, the snowshoe skating usually results in a backward fall backward because a stable body position cannot readily be maintained.
Conventional snowshoes suffer from other deficiencies as well. Often the front claw accumulates snow and ice, diminishing the claw's ability to bite into the terrain and to create friction. In some designs, the snowshoe is allowed to pivot freely on the front claw mounting axis, with the result that the rear of the snowshoe drags with each step. This dragging retards rapid user movement, such as running. Other designs minimize the rear dragging by mounting the front claw so as to urge the snowshoe to return to a horizontal disposition with each step, a configuration that promotes running. But as it is lifted from the terrain with each step, the snowshoe pivots downward about the front claw's mounting axis as the snowshoe tries to return to a generally horizontal disposition. As a result, the snowshoe front pivots downward and tends to accumulate snow and trip the user, while the snowshoe rear pivots upward and throws any snow thereon forward, usually striking the user's legs.
Because of the above limitations, conventional snowshoe travel tends to be slow, and considerable practice is required before any proficiency is attained. Although snowshoe travel could provide meaningful exercise, the inability to run, and to travel downhill confidently limits recreational snowshoe use.
In conclusion, there is a need for a mechanism to minimize skating at the back of a snowshoe, and to permit a snowshoe to be used on downhill terrain. Such a mechanism should not add appreciable weight or cost to a snowshoe, and preferably could be retrofitted. Also needed is a mechanism to minimize snow accumulation at the front claw of a snowshoe. Finally, there is a need for a mechanism that minimizes snow tossing without dragging the snowshoe rear, and that lifts the snowshoe front over obstacles so as not to trip the user. A snowshoe equipped with these mechanisms would permit running and other beneficial snowshoe exercise, even by a novice. The present invention meets these needs.
SUMMARY OF THE INVENTION
The present invention is a snowshoe that includes a frame that is at least partially covered by a membrane, and a front claw that is biasedly mounted to the frame at an offset. This biased mounting urges the snowshoe rear to pivot down and away from the user's foot, thereby minimizing snow throwing by the back of the snowshoe, without producing dragging. Further, because the front of the snowshoe is simultaneously urged upward toward the user, there is little tendency for the snowshoe front to collect snow and trip the user. This pivot action is especially beneficial when the snowshoe is used in soft snow, because it enables a user to step out of a deep hole without tripping. This front claw offset bias mounting is in contrast to the prior art, wherein biasing is either absent or restores a horizontal snowshoe disposition without offset.
The front claw is preferably mounted to the frame with at least one resilient strap, with the front claw walls projecting downward, below the plane of the frame. So mounted, the front claw tends not to accumulate snow between the front claw walls for several reasons. First, use of the snowshoe creates vibrations that are transmitted via the mounting straps to the snow facing surface of the front claw where they tend to shake loose any snow accumulating within the front claw. Second, the mounting strap material preferably is a poor thermal conductor relative to the front claw. As a result, the mounting-strap covered surface of the front claw is relatively “warm” and tends to retard snow from freezing to the front claw. Preferably a piece of freeze-resistant membrane material covers the mounting-straps on the undersurface of the front claw, to further minimize debris accumulation.
The present invention also provides a rear cleat that minimizes skating and sliding at the rear of the snowshoe, and improves friction when going downhill. The rear cleat preferably includes a debris facing surface to which at least one projecting wall is attached. Preferably the rear cleat includes first and second projecting walls that converge rearward without meeting, and are inclined relative to the debris facing surface. Because they preferably do not meet, the projecting walls leave an open area at the rear so as not to trap snow within the cleat.
A rear cleat according to the present invention may be mounted at a rear portion of the membrane, with the projecting walls penetrating downward through the membrane. So mounted, the rear cleat tends not to accumulate snow for the same reasons that the front claw tends not to accumulate snow. Alternatively, a rear cleat according to the present invention may be attached to the snowshoe frame.
Further, a rear cleat according to the present invention may be provided as a retrofit accessory for an existing snowshoe. In one embodiment, a rear cleat may be provided as a retrofit accessory for the user's boot. In this embodiment, the cleat attaches to the boot heel and the cleat wall projects downward through an opening made in the membrane on an existing snowshoe.
A snowshoe provided with a rear cleat according to the present invention may be used confidently on downhill terrain. Further, because the rear cleat minimizes rear skating or sliding, relatively little practice will be required before attaining proficiency on the snowshoe.
Finally, the present invention includes straps that preferably have a hook and loop fastening material (e.g., Velcro™ brand material) for attaching the snowshoe to a user's foot. Such straps allow the user to attach or adjust the snowshoe in freezing weather, even while wearing bulky mittens.
It is an objective of the present invention to provide a snowshoe that minimizes rear sliding or skating, and that may be used by a novice without substantial practice over all types of terrain, including downhill. This objective is met by providing a snowshoe with a rear cleat as described, or by providing a user&apo
Klebahn Perry A.
Klingbeil James D.
Freiburger Thomas M.
Kavanaugh Ted
Tubbs Snowshoe Company
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