U.S. patent number 3,673,713 [Application Number 05/147,321] was granted by the patent office on 1972-07-04 for high-lift snow shoe.
Invention is credited to Anthony Fedewitz.
United States Patent |
3,673,713 |
Fedewitz |
July 4, 1972 |
HIGH-LIFT SNOW SHOE
Abstract
In a preferred embodiment, a snow shoe of injection-molded
polypropylene, the tread of the snow shoe having a plurality of
resiliently polypropylene-hinged valve flaps angled downwardly at
about 45.degree., as measured from a horizontal, within a
respective open cell space per flap such that as the snow shoe --
on the boot of the wearer -- is pressed downwardly the snow causes
the flap to move upwardly to thereby close-off the open space to
substantially prevent large quantities of snow from passing through
the open space, to cause the trapped snow pushing upwardly against
the underside face of the flap to contribute to lifting force
against the flap which is pressed against a stop "limiting means"
thereby supporting the snow shoe tread and snow shoe wearer on top
of the snow, but also such that when the snow shoe is lifted the
snow collected on the upper face thereof and on the upper face of
the flap falls through the open space as the flap returns
resiliently to the downwardly angled molded position.
Inventors: |
Fedewitz; Anthony (Cedar Grove,
NJ) |
Family
ID: |
22521099 |
Appl.
No.: |
05/147,321 |
Filed: |
May 27, 1971 |
Current U.S.
Class: |
36/125;
36/87 |
Current CPC
Class: |
A63C
13/005 (20130101); A63C 13/006 (20130101) |
Current International
Class: |
A63C
13/00 (20060101); A43b 000/00 () |
Field of
Search: |
;36/2.5R,2.5AB |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawson; Patrick D.
Claims
I claim:
1. An article comprising, in combination: at least one plastic
one-way valve means comprising a support structure; continuous with
an upper portion of said support structure at least one unitary
resilient first hinge means extending from said upper portion along
said longitudinal axis; a valve flap continuous and unitary with
said hinge means, said valve flap having an outer edge opposite an
edge adjoining said first hinge, said valve flap relative to a
horizontal plane, extending from said longitudinal axis at a
substantially fixed angle ranging from about 20.degree. to about
70.degree.; said support structure being shaped to provide a
structure-free space extending from above to below said article
such that said valve flap is pivotably flexible upwardly on said
hinge means through an arc of at least part of said angle and such
that as said article is pressed downwardly onto a substantially
flowable particulate composition, said valve flap is pressed
upwardly through said arc by said composition and also such that
portions of said particulate composition on top of said valve flap
is flowable downwardly past said valve flap when said valve flap
resiliently returns to said substantially fixed angle, said
structure-free space extending from said flap's said outer edge at
least about one-fourth inch as measured along a horizontal
imaginary axis extending outwardly from said outer edge, said valve
flap ranging from about 0.015 inch to about 0.15 inch in thickness
and between said first hinge means and said outer edge a width
ranging from about 3/8 to about 11/4 inches, said plastic valve
means consisting essentially of semi-flexible polymer, said support
including stop means to limit said flap's upward pivotable flexure
to a predetermined maximum number of degrees, and said hinge means
ranging in thickness from about 0.002 inch to about 0.015 inch.
2. An article according to claim 1, further including a plurality
of said one-way valve means continuous and unitary with
one-another.
3. An article according to claim 2, in which said flexible polymer
is polyolefin.
4. An article according to claim 2, in which said flexible polymer
is unfilled nylon.
5. An article according to claim 2, in which said flexible polymer
is polyvinyl polymers.
6. An article according to claim 2, shaped to form a snow shoe
tread ranging from about 20 inches to about 36 inches in length and
from about 9 inches to about 16 inches in width.
7. An article according to claim 6, including means for attaching
said snow shoe tread to a boot sole.
8. An article according to claim 7, in which said attaching means
includes, continuous and unitary with said tread, resilient second
hinge means and boot sole-support structure attached pivotably to
said second hinge means.
9. An article according to claim 8, in which said boot sole-support
structure and said second hinge means are hinge and plate jointly
extending about 3 inches to about 9 inches in width as measured
along an imaginary axis parallel to said second hinge means, and of
about 2 inches to about 7 inches in length as measured along an
imaginary axis about perpendicular to said second hinge means and
in which said hinge extends into a hole through said support
structure.
10. An article according to claim 9, in which said plate includes
at least one through-slit adjacent each of opposite plate edges
extending through the plate's upper and lower faces for inserting
therethrough a boot-securing strap.
11. An article according to claim 10, in which said plate includes
a plurality of said through-slit ranging consecutively inwardly
from each of inner and outer edges of said plate such that optional
slit-engaging strap positions are available for variable boot
widths, and in which said second hinge means and said plate are
defined by a continuous through-space extending through said tread
to circumscribe about three sides of said plate and opposite ends
of said second hinge means, said plate being pivotable upwardly out
of said through-space.
12. An article according to claim 11, in which said second hinge
means extends rearwardly from a forward portion of said tread
forward of said through-space such that said hinge plate pivots
forwardly when a mounted boot's heel is raised and arched
forwardly.
13. An article according to claim 12, in which said support
structure is cellular in shape, in which said support structure
includes a substantially upright wall extending along an imaginary
longitudinal axis with said longitudinal axis during said article's
use being employable substantially in a horizontal position, and in
which at least two of said flaps are hinged within at least one of
a plurality of adjoined cells and said two flaps extend about
toward each other defining a narrow space between opposing flaps'
said outer edge.
14. An article according to claim 13, in which a lower portion of
each said through-slit is enlarged relative to the through-slit's
upper channel.
15. An article according to claim 13, in which said one cell's
depth ranges from about 3/8 inch to about 11/2 inches.
16. An article according to claim 15, in which said angle ranges
from about 40.degree. to about 50.degree., said structure-free
space ranges from about 3/8 inch to about 11/4 inches, said flap
thickness ranges from about 0.011 inch to about 0.11 inch and in
width from about one-half to three-fourths inch, said cell's depth
ranges from about one-half inch to about five-eighths inch, said
snow ranges in length from about 25 inches to about 30 inches and
in width from about 11 inches to about 14 inches, said second hinge
means is of thinner thickness than said plate's average thickness,
said plate ranges in length from about 4 inches to about 6 inches
and in width from about 41/2 inches to about 6 inches, said hinge
means ranges from about 0.006 inches to about 0.011 inches, and
said flexible polymer is polyolefin.
17. An article according to claim 15 wherein said flexible polymer
is unfilled nylon.
18. An article according to claim 15 wherein said flexible polymer
is polyvinyl polymers.
19. An article according to claim 10, in which said second hinge
means and said plate are defined by a continuous through-space
comprising said hole extending through said tread to circumscribe
about three sides of said plate and opposite ends of said second
hinge means, said plate being pivotable upwardly out of said
through-space, and in which said hinge means extends rearwardly
from a forward portion of said tread forward of said through-space
such that said hinge plate is pivotable forwardly when a mounted
boot's heel is raised and arched forwardly.
20. An article according to claim 19, in which a lower portion of
each said through-slit is enlarged relative to the through-slit's
upper portion.
21. An article according to claim 2, in which back-to-back ones of
said flap extend in about opposite directions from back-to-back
ones of said first hinge means mounted on a common said upright
wall.
22. An article according to claim 1, in which said polymer is
polypropylene.
23. An article according to claim 1, in which said support
structure forms at least one cell in which at least two of said
flaps are hinged within said cell with one flap hinged on one side
of the cell and the other of the two flaps hinged on an opposite
side of the cell such that the two flaps extend about toward each
other defining a narrow space between opposing flaps' outer
edge.
24. An article according to claim 1, in which said support
structure forms at least one cell of which said upright wall is one
of the cell's walls, with said flap hinged within the and with said
structure-free space between said outer edge and an opposite wall
of said cell ranging from said about 1/4 inch to about 2
inches.
25. An article according to claim 12, in which said plate includes
on its lower face adjacent opposite inner and outer edges
downwardly projecting guide means for guiding downward pivotable
movement of said plate into said through-space and for limiting
sideward shifting of said plate within said free space.
26. An article according to claim 12, in which said snow shoe tread
includes a toe hole therethrough in a tread portion anterior to
said forward-portion second hinge-support structure, said second
hinge-support structure being substantially U-shaped with each
U-leg angling rearwardly toward the snow shoe tread's posterior
end, angling substantially around opposite ends of said opposite
ends of said second hinge whereby said second hinge-support
structure has inherent hinge-action flexibility for downward
bending.
27. A snow shoe tread comprising an injection-molded plastic tread
of a plastic composition selected from the group consisting of
polyolefin, unfilled nylon, and polyvinyl polymers, said tread
including a continuous and unitary attaching means comprising a
hinge means and a boot sole-support structure attached pivotably to
said hinge means, in which said hinge means and said boot
sole-support structure are defined by a continuous through-space
extending through said tread to circumscribe about three sides of
said boot sole-support structure and opposite ends of said hinge
means, said boot sole-support structure being pivotable upwardly
out of said through-space, said hinge means extending rearwardly
from a forward portion of said tread forward of said through space
such that said hinged boot sole-support structure pivots forwardly
when a mounted boot's heel is raised and arched forwardly, and said
snow shoe tread including a toe hole therethrough in a tread
portion anterior to said through-space, said tread including a
hinge-support portion from which said hinge extends, said
hinge-support structure extending forwardly into said hole, said
hole extending rearwardly on opposite sides of said hinge-support
structure such that said hinge-support structure is depressable
downwardly when a boot mounted on said sole-support is pivoted
forwardly as the boot's heel is raised and the boot arched
forwardly.
Description
This invention relates to an improved snow shoe which is capable of
supporting greater weights in soft snow or holding the wearer
higher in the soft snow with concurrently reduced snow shoe size,
as compared to prior art snow shoes heretofore available.
BACKGROUND
Although it has long been recognized that maximum lift of a snow
shoe would be obtainable if there were no holes or perforations in
the snow shoe tread, it also has been recognized that heretofore
such a tread would not be useable nor practical because soft snow
rapidly collects on top of such a tread. This collected snow makes
it increasingly difficult if not impossible to lift the snow shoe
or to walk with the snow shoe attached. Accordingly, the
controlling feature of any practical snow shoe has been the
provision of providing an effective structure for making sure that
the snow tending to accumulate on top falls through the tread.
Providing such necessary escape spaces for accumulated snow has
however required that the snow shoe width and length be
proportionately greater than a hole-less shoe, in order that an
equivalent amount of surface area be available for pressing
downwardly into the snow. However, because a snow shoe having such
an equivalent surface area -- and thereby an equivalent amount of
lift, would be of too great a width and/or too great of length to
be conveniently or practically maneuverable or controllable, "lift"
has been heretofore sacrificed by compromising to a snow shoe of
reduced size but with snow-escape spaces or holes extending through
the tread. For example, long years ago and still in some areas of
the world, snow shoes are made from a bowed strip of wood with the
opposite ends thereof pointed in a common direction and bound
together side-by-side, with rawhide webbing strung across and laced
to provide supporting surface area with openings provided in the
webbing to prevent the accumulation of snow on top of the tread. In
addition to the problems already noted above for such a snow shoe,
the treated or varnished rawhide quickly wears-off the protective
coating and the raw hide deteriorates, as well as absorbing
moisture. Similarly the varnish or other wood coating or treatment
becomes worn and thereafter the wood is subject to becoming
water-logged. Moreover in extreme depths of soft snow, extreme
sizes of snow shoes are essential conventionally for a
pack-carrying wearer.
In addition to problems of the type discussed above, both extreme
sizes as well as less than optimally desireable means for attaching
the tread to the boot of the wearer have added to the problems of
control, maneuverability, ease of walking, speed of movement and/or
walking and the like. For example, a common problem is the shifting
of the boot to an out-of-alignment position and/or the boot
shifting to one side or the other as slopes or mounds of snow or
ice are encountered or during an attempted change of direction, for
example.
Some prior snow shoes weigh two pounds or more, thereby causing
great weariness to a wearer on an extended trek or journey.
More recently there have been produced plastic snow shoes which at
least are light weight. However, not all plastics are suitable for
cold exposure, becoming very brittle and easily broken.
Alternatively, flexible plastic heretofore has been subject to the
disadvantage of the bending of the snow shoe responsive to the
weight of the wearer such that balance and control become difficult
as well as the wearer sinking further into the snow because the
outer portions of the tread flex upwardly when the central portion
of the tread sinks downwardly as the tread bends beneath the
wearer's weight; sinking further into the snow requires the wearer
to lift higher his snow shoe for the next step. Also such plastic
shoes continue to require the large size because of the
still-needed snow-escape spaces or perforations throughout the face
of the tread of each snow shoe.
In order for the snow-shoe wearer's heel to arch forward, normally
there has been a hinge action provided for. For some years flexible
plastics such as polypropylene have been known to be suitable for
bending and/or hinge-pivotable action. Although a plastic snow shoe
has been desireable to obtain an advantage of light weight as well
as the convenience and reduced cost of an injection molded tread
and hinge, such a plastic tread has typically encountered the
problem of too great flexibility, i.e. the snow shoe tread of
insufficient rigidity bending under the wearer's weight, as
discussed above.
In snow shoes prior to this invention, partially as a result of the
cumbrous shoes necessary for obtaining a practical amount of lift,
but additionally because of the method, mechanism, and/or location
of attaching the snow shoes to the boot of the wearer, forward,
rearward and/or angular movement of the boot relative to the
respective tread has(have) resulted in a frustrating lack of
maneuverability of and control in walking with the snow shoes.
A part of the difficulty in obtaining a securing snow shoe
mechanism absent of boot movement forward, rearward, and/or
angularly has arisen from the need of freedom of the boot heel to
rise from the surface of the tread as the foot of the wearer is
arched forward during the normal course of walking with the snow
shoe attached.
Other typical factors involved in the producing of snow shoes, as
well as in any constructive attempts to overcome one or more of the
above type problems, include the employment of waterproof and/or
non-warping materials, high-level strength and durability,
reasonableness of manufacture, adaptability to mass production,
resistance to wear and weather conditions, adaptability to
different types of boots or other foot-wear, adaptability to
different sizes of foot-wear, simplicity of design, together with
the major factors of lift and control already discussed at length
above.
SUMMARY OF THE INVENTION
The overcoming of the above problems are among the objects of this
invention, as well as other objects apparent from the preceding and
following disclosure, and one or more of these objects are obtained
by one or more embodiments of this invention. The invention
includes a high-lift valve which imparts a high degree of lifting
capacity to a snow shoe embodying a plurality of the lift valves,
while concurrently providing a mechanism whereby soft snow tending
to accumulate on the upper face of the snow shoe tread escapes
through spaces opening in the tread as weight is taken off-of the
snow shoe and the snow shoe lifted in the normal course of walking
of the wearer of the snow shoe. The snow shoe tread is
substantially in its entirety molded (by normally injection
molding) from a resilient polymeric material, hereafter referred to
as "plastic," such as well-known conventional (or other desirable)
semi-flexible polymer selected from the group consisting of
polyolefin, unfilled nylon, and polyvinyl polymers, preferably
polypropylene or polyethylene, provided that the particular one(s)
of such polymers are characterized by flexibility of a nature
adaptable to this invention; for example, a completely elastic
composition would not be adaptable because of the lack of
resistance to bending under the weight of the wearer, whereas a
composition without any significant resiliency would be subject to
either breaking and/or providing a plastic valve which would not
function properly, as described hereafter. However, as is well
known in the polymer art, elastic polymeric compositions may be
modified in their characteristics to provide increased rigidity --
i.e. to become a little less elastic -- by the incorporation of
filler and/or by other known and/or desired methods. The plastic,
such as for example any of those noted above, is suitable for the
snow-shoe tread in having the desired flexibility and resiliency
for the high-lift valve while concurrently (particularly when in
the inventive cellular form of the preferred valve cells) providing
rigidity for the snow-shoe support structure.
Thus, the tread and the high-lift valve are both of the plastic
material, molded concurrently as a single, unitary injection (for
example) molded product preferably in a cellular form with one or
more valveflaps per cell. The cellular form serves to protect the
valve(s) as well as providing a structure less susceptable to
bending under the weight of the snow shoe wearer. The high-lift
valve is in effect a substantially one-way valve substantially
preventing snow from rising completely through the snow shoe onto
the top of the tread, providing for the trapping of snow beneath
the lower surface of the tread, and providing for the escape
through the tread of soft snow accumulated on the upper face of the
snow shoe tread. The high-lift valve is a plastic flap hinged by a
thin (normally thinner) plastic hinge to a plastic part of the
tread structure, the valve flap, hinge and tread structure being
integral and unitary, with the valve flap molded in a position
angled obliquely downwardly (i.e. slanted downwardly), relative to
a horizontal (the typical tread faces normally being parallel to a
horizontal), at an angle ranging from about 20.degree. to about
70.degree., with the tread support structure being shaped to
provide a structure-free space extending from above to below the
snow shoe tread such that the flap is pivotably flexible upwardly
on the hinge through an arc of at least part of the angle and such
that as the article is pressed downwardly onto a substantially
flowable particulate composition such as soft snow, the flap is
thereby pressed upwardly through the arc by the composition trapped
under and also such that portions of the particulate composition on
top of the flap is flowable downwardly past the flap when the flap
resiliently returns to its fixed (molded) angle (downwardly
slanted).
THE FIGURES
FIG. 1 illustrates a typical and preferred embodiment of the
invention, disclosing an elevation plan view of an upper surface of
a snow shoe embodying the high-lift one-way valves.
FIG. 2 is a cross-section taken along lines 2--2 of FIG. 1.
FIG. 3 is a cross-section taken along lines 3--3 of FIG. 1 as such
a cross-section would appear when strapped to a wearer's boot
during an arching forward of the boot heel as occurs after a step
and preparatory to lifting the snow shoe in a next step.
FIG. 4 illustrates an elevation plan view of a portion of a lower
face of a snow shoe tread such as the snow shoe of FIG. 1, the
illustrated portion disclosing a typical cell structure having two
high-lift valve flaps within the single cell, one hinge and flap
being mounted in one end and the other hinge and flap being mounted
in the opposite end of the cell.
FIG. 5 illustrates a typical cross-sectional side view of a portion
of the boot-mounting plate and strap attaching means, disclosing a
preferred wedge-securing device for firmly but simply securing the
strap to the plate.
FIG. 6 illustrates two back-to-back cells with back-to-back hinges
from a common support structure portion.
DETAILED DESCRIPTION OF THE INVENTION
The primary function of the inventive lift valve is to provide for
resistance to flow in one direction -- upward through the snow shoe
tread -- and utilizing that resistance to provide weight-carrying
capacity or lift, and to provide for reduced and little resistance
to snow flow downwardly through the snow shoe tread. The weight
carrying capacity of any given snow shoe is a function of its
projected surface contact area on the lower face of the snow shoe
tread. Because of the many snow-escape holes extending through the
surface of heretofore snow shoe treads, lower tread face contact
area constituted only a small percentage of the total area
encompassed by the periphery of the snow shoe. By virtue of the
snow shoe including a plurality of the inventive high-lift valves,
the inventive snow shoe approaches the efficiency of a flat plane
and yet is self-purging of soft snow tending to accumulate on the
upper surface of the tread. The cellular structure provides
protection of the flap 6 while concurrently providing both strength
and rigidity to thereby dispense with the requirements of both
separate frame and conventional webb construction thereby also
reducing the need for the additional weight of such parts.
As illustrated in FIG. 2, the greater minimum valve-flap 6a
thickness at the outer edge which engages the stop in the closed
position is necessary to prevent the flap under pressure from
flexing at that point and sliding (when flexed) past the stop 16a;
flexing at the hinge area -- sufficiently for the flap to slip past
the stop -- is a less likely possibility because of reduced
leverage against the flap at that point, and therefore the flap
near the hinge 18a and the hinge itself may be thinner for optimal
pivoting action of the flap; also the thinner flap toward the hinge
18a allows snow-shoe weight reduction by virtue of reduced total
mass.
The snow shoe tread may optionally omit a toe hole in the tread of
this invention, thereby (when omitted) further reducing the
open-space normally in a snow shoe tread; in a tread of this
invention omitting the toe hole, the boot-support plate 7 is of
longer length (as measured from anterior to posterior ends of the
snow shoe tread) with the entire boot-toe end remaining on the
plate, preferably abutting a stop projecting upward from the
forward end of the plate to prevent the toe of the boot from
extending forward beyond the plate hinge 8. However, in an
illustrated preferred embodiment of FIGS. 1 and 3, the forward toe
flap 9 extends beyond (or at least as far as) the boot toe and the
body of the tread is either molded such that, or the body of the
tread is slit (cut) such that, the slit-space substantially
circumscribes the boot-toe portion with the slit on each side of
the boot-toe portion 9 to slit-termination points 10a and 10b about
adjacent opposite ends of the hinge 8 but preferably angled away
from the hinge ends so that substantially high strengths exists
between the slit-termination points and the hinge ends, whereby
there is hinge action provided for the boot-toe portion 9 when the
wearer's boot is arched forward as illustrated in FIG. 3 but
whereby normally in the stepping position and weight-carrying
position the boot-toe portion 9 is in its normally fixed (where
molded) position in the same horizontal plane as the upper and
lower faces of the snow shoe tread, thereby the lower face of the
boot-toe portion 9 providing additional lift as compared to a snow
shoe tread having an open-toe hole extending through the tread.
Also, in this FIG. 3 illustrated embodiment, the plate 7 and hinge
8 are not required to carry alone the wearer's weight because a
substantial portion of the wearer's weight is carried by the
support structure portion 11. On the anterior portion of the upper
face of the boot-toe portion 9 is illustrated an optional boot-toe
stop 12, in FIG. 1.
In FIG. 1, typically illustrated are: boot-heel support portion 13;
plate hinge area of hinge 8; through-aperture or through-slit such
as 14b, and 14c; cell flap 6a of single cell 15 having stop 16a and
16b at opposite ends of the cell projecting from the support
structure forming the periphery of the cell; normally the edges of
the cell from which the stops 16 (a and b) extend constitute the
tops of the respective walls such as stop 16aa (as viewed from the
bottom of the double cell -- i.e. two hinges and two flaps,
opposing each other from opposite ends of the cell -- of FIG. 4)
extending from the top of wall 17aa and stop 16bb extending from
the top of wall 17cc, whereas in FIG. 2 flap 6a extends from the
hinge 18a of thinner cross-section than support structure portion
19 and thinner than the flap 6a; in the FIG. 2 it may be seen that
the hinge 18a in this embodiment extends directly from the top of
the cell wall 17d which is opposite (across the cell from) cell
wall 17b. It should be noted however that the cellular walls need
not necessarily be adjacent the opening which the flap 6 serves to
close and open; however, in a preferred embodiment, the cell walls
define the opening typically as illustrated in FIGS. 2 and 4. FIG.
1 additionally illustrates double cells such as double cell 20,
straps 21a, 21b, lace 22, strap 21c, knoted bow 23, previously
listed toe flap 9, hinge-action portion 24a and hinge-action
portion 24b, previously mentioned boot-toe stop 12, slit (or molded
space) 25 extending between slit-termination points 10a and 10b,
slit (or space) 26 (between the circumscribing support-structure
edges 28a, b, and c) defining the boot-support plate 7, guide 27
for serving to guide the plate downwardly into the space defined by
the slit 26 (when the plate 7 is pivoted upwardly) as well as for
serving to facilitate the prevention of any sideward shifting
movement of the plate 7 when the plate is in its downward
weight-supporting position. Preferably the edges of the plate are
cut after molding and cut at an inward angle such that when in the
down position the upper edge of the plate 7 presses downwardly on
the lower angular edge of the support structure portions 28a and
28b and 28c. The boot-toe portion 9 may be additionally optionally
hinged from (by a hinge section such as hinge 8 -- of the same
type, that is) the portions 24a and 24b with the additional hinge
extending across the width of the boot-toe portion 9.
Although solely single and double cells are illustrated in FIGS. 1,
2, and 3, it is possible to have varying arrangements of the flaps
and/or to have three, four, or more flaps per cell. However, a
particular advantage of the double cell illustrated in FIG. 4, for
example, is that valve flap support surface area is approximately
twice the single cell valve flap support surface area, while the
upper tread face-opening nevertheless has typical space 29 between
opposing outer edges 30a and 30b of flaps 6b and 6c; this space 29
is of about the same area across as space 31 of cell 15, whereby
when closed upwardly the flaps 6b and 6c substantially close the
upper tread face opening of the double cell. It should be noted
that such a closed opening is not so easily accomplished with a
single cell, because -- as a limitation imposed by an injection
mold method of making the cell-containing snow shoe -- the flap 6a
as molded at the fixed angle (typically as illustrated in FIG. 2)
must be sufficiently short so as not to extend beneath the
projecting flap stop 16a in order that after the injection molding
operation -- a mass production method to reduce cost and thereby
make practical the making of such a plastic shoe -- the cell (or
snow shoe of which the cell is a part) may be lifted from the mold;
if the flap as molded extended beneath or beyond the stop 16a, the
hardened plastic cell could not be removed from its mold. Also, if
the flap is molded angled (slanted) downwardly to too great an
extent, the downward movement of the cell into soft snow (for
example) will not result in enough leverage and/or enough snow
pressing against the underside face of the flap to cause the flap
to move upwardly, as well as causing the edge 30c of the flap to
dig into the snow, the snow thereby jamming the closing action of
the valve, and the valve generally being inoperative.
Alternatively, if space 31 becomes too narrow, snow cannot escape
therethrough. Accordingly, there is a substantive limit to the
operable downward angle as well as a practical and substantive
limit (if injection molding is to be employed) to the length of the
flap so as not to extend under nor beyond the stop 16a. Thus both
the larger upper tread cell face space as well as the mechanism to
substantially totally close that space is a real advantage,
obtaining a complete plane without opening therein and thereby
maximum lift in a double cell.
For either single or double cells, the closing action -- i.e. the
extent to which the opening is more completely closed -- is further
improved by virtue of the increased thickness of edge 30c as
illustrated -- i.e. the greater thickness together with the angled
edge (relative to the faces of the flap) maximizes the reach of the
flap for closing purposes, while adding strength and durability to
the flap.
The movement indication arrow 32 illustrates the path of movement
of the flap 6a to the closed position when pressured upwardly by
snow (for example) when the cell is pressured downwardly.
The movement indication arrow 33 illustrates the path of movement
of the hinged plate 7 between the open and closed positions.
In FIG. 3, although the illustrated hinge 8 is a double hinge, a
single hinge may be employed. However, the advantage of a double
hinge is that because of the double hinge action, there is less
bending of the plastic hinge required and accordingly a thicker
hinge may be employed in view of the double hinge limiting the
maximum stress that would probably ever (normally) be placed on
either of the single hinges making up the double hinge. The thicker
hinge naturally has greater strength and durability, and not only
is less apt to break or tear but also is less flexible in shifting
sideward movement as compared to the situation that would exist
with a thinner hinge. Yet there is ample upwardly and downwardly
flexibility as needed.
The FIG. 5 serves to illustrate how the strap 21a (for example) is
removably anchored into a molded slot 38 designed for a wedge-lock
mechanism, whereby the wedge 34 -- the terminal end of strap 21a --
is easily inserted into the locking position but is removable if
and when desired, such as to adjust for the width of wearer's boot
or to replace a worn or severed strap 21a.
Although a particular typical harness means is illustrated as
straps such as 21a, 21b, 21c, lace 22, and lace bow 23, any
suitable, conventional, and/or desirable harness may be employed
preferably employing the strap attaching mechanism of FIG. 5, and
the through-slits or other attaching means may be located on any
one or more support portions such as 7, 9, or 18d, for example.
Although a preferred attaching means for the strap is illustrated
in FIG. 5, any desirable, suitable, and/or conventional attaching
means and mechanism may be employed.
Similarly, although a preferred boot-securing means is illustrated
and described, any desired, suitable, and/or conventional
boot-securing means and mechanism may be employed.
In the illustrated embodiment of FIG. 1, there are provided a
plurality of through-slits such as 14a, 14b, and 14c, either molded
as through-slit 34a (see FIG. 5) or cut thereinto subsequent to
(i.e., after) the molding operation on opposite sides of the
boot-securing position, providing optional slits for different
width boots; however, part or all of the through-slits may be
through the support structure (other than the plate) adjacent or
anterior to the plate, and/or on the boot-toe portion for example,
as might be desired. This is a preferred embodiment, incorporating
the plurality of optionally alternative through-slits, the result
being that with the strap snugly fitting the almost exact width of
boot of the wearer, there is reduced or eliminated any remaining
substantial possibility of shifting of the boot sidewardly in the
strap harness. It should further be noted, however, that such
through slits are also appropriate for the employment of a
belt-like strap downwardly into a slit on one side of the boot and
upwardly through another slit on the opposite side of the boot. In
the illustration of FIG. 1, extending from boot-toe portion 9
straps such as 21d extend from through-slits such as 14c to join
straps 21a and 21b.
For purposes of this disclosure, the width of the flap 6 refers to
a measurement along imaginary axis 36, whereas the length of the
flap 6 refers to a measurement along imaginary axis 35. The angle
37 is the angle of the downwardly angled flap 6, the angle at which
the flap is fixedly molded.
As stated above, the angle 37 may range from about 20.degree. to
about 70.degree., but preferably ranges from about 40.degree. to
about 50.degree.. The flap 6 (6a, 6b, etc.) thickness may range
from about 0.011 inches to about 0.15, but preferably ranges from
about 0.02 inches to about 0.11 inches. The flap hinge 18a ranges
normally from about 0.002 inches to about 0.015 inches, but
preferably ranges from about 0.006 inches to about 0.011 inches.
The cell depth as measured along imaginary axis 39 normally ranges
from about 3/8 inch to about 11/2 inches, but preferably from about
one-half inch to about five-eighths inch. The flap width normally
ranges from about 3/8 inch to about 11/2 inches, but preferably
from about one-half inch to about three-quarters inch, and the
length ranges normally from about 1/2 inch to about 6 inches,
preferably from about 1 inch to about 4 inches. The space 31
normally ranges from about 1/4 inch to about 2 inches, but
preferably from about 3/8 inch to about 11/4 inch. The overall snow
shoe tread length normally ranges from about 20 inches to 36
inches, but preferably ranges from about 25 inches to about 30
inches, and normally has a width ranging from about 9 inches to
about 16 inches but preferably from about 11 inches to about 14
inches. The boot plate length normally ranges from about 3 inches
to about 9 inches, preferably from about 4 inches to about 6
inches, and in width normally from about 4 inches to about 7
inches, preferably from about 4.5 inches to about 6 inches.
To maintain proper grip on ice crusted snow surfaces, the lower
edge portions of the high-lift snow shoe may have off-set edges,
and/or serrated or toothed edges, and/or may include molded holes,
indentations, or slots for the insertion of typically metal
ice-cleats, for example.
Instead of the wedge-lock strap terminal illustrated in FIG. 5, the
terminal portion may be T-shaped or any other shape suitable for
providing a locked-in strap terminal; with the T-shaped terminal,
the hole molded into the shoe therefor would be molded a fraction
of an inch smaller than the T-terminal so as to provide for a
wedging snug and locked fit.
The heel plate on the upper surface of the tread is preferably a
rough finish and/or a serrated surface, in order that any tendency
for the boot heel to slip sideward will be reduced. Similarly also
preferably the plate 7 surface and the boot-toe portion 9 surface
have a rough finish and/or a serrated surface to further reduce any
tendency for the boot sole to slip forwardly, backwardly, and/or
sidewardly.
Although in the preceding disclosure there has been discussed
solely a snow-shoe embodiment of the inventive high-lift valve of
this invention, the valve and structure may be equally well
employed to any flowable particulate composition other than soft
snow discussed above, other typical compositions being for example
a grain within a grain bin or the like, where it is desirable that
the worker not sink-down beneath the surface thereof.
FIG. 6 illustrates back-to-back valve flaps 6b and 6c hinged by
hinges 18b and 18c from a common support portion, where two single
cells are back-to-back if and when desired. Also a single cell can
be back to a double cell, or two double cells back-to-back.
It should also be noted that if desired, single-flap containing
cells may circumscribe (for example) the snow shoe periphery and be
facing outwardly from the boot at each cell's respective location
and concurrently be absent an outer wall -- i.e. absent the wall
17b -- whereby the space beyond the flap edge 30 (space normally
designated 30c) may be infinite -- the flap edges 30 in such an
embodiment having no protective snow shoe outside-frame structure,
i.e. such cells being three-walled cells, such as the trailing
cells of FIG. 1.
The cellular walls such as 17a, b, c, and d are preferably thicker
along imaginary axis 40 at points nearer the central portions of
the snow shoe and tapered to thinner cross-section at points
distant from the central portions, since the outer portions are not
required to be as strong and sturdy. The thicker wall portions
prevent flexing action of the central portions of the tread
structure and the transmital of snow shoe wearer's weight to the
outer portions; for example the support structure between cells is
thicker at 40a than at 40b. The thinner outer portions thereby are
not any larger nor heavier than necessary, resulting in a
lighter-weight snow shoe.
Although cellular structure typically having walls 17a, b, c, and d
are preferred, the tread may alternatively be a substantially plane
surface having the valved surface as illustrated in FIG. 1, but
with sturdy (preferably tapered) struts in any desired underside
supporting and/or reinforcing structure as a separate or unitary
constructed or molded part of the planar tread surface.
There are modifications which to the ordinary artisan in this art
would be obvious, although all possible variations and equivalents
have not been discussed in this disclosure. Accordingly, it is
within the scope of this invention to employ such modifications and
use such equivalents which fall within the spirit of this
invention.
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