Note: Descriptions are shown in the official language in which they were submitted.
CA 02882071 2015-02-13
TITLE OF INVENTION
TIRE CHAIN LINK
FIELD OF THE INVENTION
This invention relates to tire chain links for use with heavy duty vehicles
such as
for mining and forestry applications.
BACKGROUND OF THE INVENTION
Tire chain link meshes are formed by attaching links to rings so as to
interconnect the links and form a mesh pattern. Typically, the links include
attachment apertures through which the rings are threaded. Clearance between
io the rings and the edges of the apertures allow the links to move about
the ring,
making the tire chain as a whole flexible and enabling it to be installed on
the tire.
However the ability of the links to move about the rings of the tire chain can
cause friction between adjacent links and accordingly the links can tend to
wear
unevenly.
The principal functions of tire chains are to provide protection against tread
wear
and to enhance traction. When used in the abrasive environments of mines, the
design of tire chains tends to be optimized for protection against wear. In
other
applications, such as forestry, traction enhancement is a more important
objective.
The design of tire chains usually involves a trade-off between the two
functions.
In applications where wear protection is more important, relatively small
pitch
lengths (the span between the distal inner edges of the attachment apertures)
such as 63 millimeters or 73 millimeters are used, resulting in relatively
tight
mesh patterns that maximize tread protection. However short pitch lengths and
tight meshes increase the likelihood of trapping debris, snow and ice between
the
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links thereby impeding rather than enhancing traction in forestry and similar
environments.
Tire chain links sometimes provide a featureless working surface such as in
U.S.
Patent No. 3,892,268 to Asbeck. However it is more common, particularly for
traction tire chains, to provide studs on the working surface of the links.
U.S.
Patent No. 5,058,645 to MCiller provides a single V-shaped profiled element;
U.S.
Patent No. 4,357,975 to Baldry provides a plurality of arcuate upstanding
plates;
and U.S. Patent No. 6,520,231 to Dohmeler provides a plurality of button
studs.
Where studded links are provided, partial rotation of the links about the
rings
allows the studs to be angled sideways, thereby reducing their effectiveness.
Prior art studded tire chain links generally feature welding of the studs to
the
main body of the link. In a typical tire chain, there may be more than 1500
welds
having regard to the welding of the studs onto the bodies of the links, the
welding
of the rings to secure them to the links and the welds associated with the tag
chains used to retain the mesh on the tire. With such a large number of welds,
weld failures can become an issue in heavy duty applications.
It is an object of the present invention to provide an enhanced traction chain
studded link for use in forestry and similar applications that presents an
improvement over one or more of the above limitations by providing an
improved,
forged link and an improved stud configuration.
These and other objects of the invention will be better understood by
reference to
the detailed description of the preferred embodiment which follows. Note that
the
objects referred to above are statements of what motivated the invention
rather
than promises. Not all of the objects are necessarily met by all embodiments
of
the invention described below or by the invention defined by each of the
claims.
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SUMMARY OF THE INVENTION
In one of its aspects, the invention comprises a forged tire chain link having
a
plurality of studs integrally forged into its top surface.
In another aspect, the attachment apertures of the link present flat rather
than
rounded inner edges to maximize the contact surface with the ring. This
feature
minimizes the tendency of the link to rotate about the ring, thereby
minimizing the
angling of the studs away from the traction surface.
A plurality of spaced studs having square cross-sections are forged into the
top
surface of the link. The square cross-sections present straight surfaces that
io enable for reliable traction. In addition, each stud is angled at 45
degrees in
relation to the longitudinal axis of the link. This compensates for the 45
degree
angle at which the link itself is presented when bound in a chain link pattern
to
provide a flat gripping surface in relation to the direction of rotation of
the tire. In
other words, a straight edge (rather than a corner) of each stud is the first
part of
each stud to contact the ground and the opposing straight edge of each stud is
the last part of each stud to leave the ground.
The vertical dimension of the longitudinal ends of the links include a medial
apex
to minimize the contact surfaces between adjacent links and to thereby limit
wear
on the links.
The central portion of the base and top of the link is smoothly beveled to a
thin
base edge to enhance the gripping of the link into the ground.
A pitch length in the range of 100 mm +/- 15 mm along with an open diamond
design for the studs provides effective traction, minimizes the build-up of
snow
and ice between the studs and provides good tread protection.
In another aspect, the invention comprises a tire chain link having an
elongated
body, two attachment apertures for receiving a linking element, and a
plurality of
spaced, upstanding studs along the body. The attachment apertures are
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separated by a bridge extending between a base and a top portion of the body.
Each of the studs has a square cross-section and the body and the studs are
integrally formed. The body has a longitudinal axis and the studs have
straight
edges. Each of the straight edges forms an angle of 45 degrees with the
longitudinal axis. The inside top and bottom surfaces of each of the
attachment
apertures are flat. The elongated body has opposed longitudinal ends and the
vertical extent of each of the ends tapers to a medial apex. A base and a top
of
the central portion of the body are smoothly beveled toward the outside of the
body. The pitch length of the link is between 85 mm and 115 mm.
io In a further aspect, the invention comprises a tire chain link having an
elongated
body, at least one attachment aperture for receiving a linking element, and a
plurality of spaced, upstanding studs aligned along the body. Each of said
studs
has a square cross-section, Each of the studs may be integrally forged with
the
body,
In another aspect, the body has a longitudinal axis and the studs have
straight
edges, each of the straight edges forming an angle of 45 degrees with the
longitudinal axis.
In another aspect, the body has two attachment apertures. The inside surface
of
each of the attachment apertures may be flat.
In yet another aspect, the invention comprises a tire chain link having an
elongated body and at least one attachment aperture for receiving a linking
element. The inside top and bottom surface of the attachment aperture is flat.
In another aspect, the invention comprises a tire chain link having an
elongated
body, at least one attachment aperture for receiving a linking element, and a
plurality of spaced, upstanding studs aligned along the body. The elongated
body has opposed longitudinal ends and the vertical extent of each of the ends
tapers to a medial apex.
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In another aspect, the base and top of the central portion of the body may be
smoothly beveled towards the outside of the body.
In a further aspect, the pitch length of the link may be between 85 mm and 115
MM.
5 The foregoing was intended as a summary only and of only some of the
aspects
of the invention. It was not intended to define the limits or requirements of
the
invention. Other aspects of the invention will be appreciated by reference to
the
detailed description of the preferred embodiments. Moreover, this summary
should be read as though the claims were incorporated herein for completeness.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described by reference to the detailed description of
the
preferred embodiment and to the drawings thereof in which:
Fig. 1 is a perspective view of the tire chain link according to one
embodiment of the present invention;
Fig. 2 is a side view of the tire chain link of Fig. 1;
Fig. 3 is an end view of the tire chain link of Fig. 1;
Fig. 4 is a top view of the tire chain link of Fig. 1;
Fig. 5 is a perspective view of the tire chain link of Fig. 1 with a ring
through one of the apertures of the tire chain link; and
Fig. 6 shows a portion of a tire link mesh over a tire composed of tire chain
links and rings of the type illustrated in Fig. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the invention is shown in Figs. 1 to 6. The tire
chain link 10 according to the preferred embodiment is entirely forged as a
single
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piece, including notably the studs 32, 34, 36 located on the top surface of
the
link.
The link 10 has a generally elongated body 11 and comprises two attachment
apertures 12, 14 located along the longitudinal extent "in of the link. The
attachment apertures 12, 14 are separated by a bridge 18 connecting the base
20 to the top portion 22 of the link. The attachment apertures 12, 14 are
adapted
to receive therethrough a ring or other linking element to form the overall
tire
chain. For example, ring 23 shown in Fig. 5 passes through aperture 14 of the
link 10.
It is contemplated that a single attachment aperture without a bridge may also
be
provided rather than two attachment apertures, although at the expense of a
likely loss of resistance to bending along the vertical medial axis depending
on
the strength of the material used to form the link 10. In a single aperature
embodiment the two rings within the link may also come into contact with one
another.
The vertical extent of each of the opposed longitudinal ends 24, 26 of the
link
body tapers to medial apices 28, 29 to minimize the contact surfaces between
adjacent links and to thereby limit wear on the links.
As best appreciated by reference to Fig. 1, the top 30 and bottom 31 interior
surfaces of the attachment apertures 12, 14 are flat rather than rounded. This
feature minimizes the angling of the link about the ring of the tire chain due
to a
greater portion of the ring being in contact with the flat surfaces 30, 31
compared
to rounded surfaces.
The base 20 and the top 22 of the body are smoothly beveled toward the outer
surfaces of the link in the areas below and above the bridge 18 to enhance the
traction of the link into the ground. As best seen in Fig. 3, the beveling
provide
paddle-like edges for gripping the ground.
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The top portion 22 of the link comprises a plurality of upstanding spaced
studs
32, 34, 36 having square cross-sections. The studs 32, 34, 36 are integrally
forged with the body. The straight edges 38, 40, 42, 44 of the studs provide
an
improved traction edge for gripping onto objects. As best appreciated by
reference to Fig. 4, the studs are angled such that each edge of the stud
forms
an angle of about 45 degrees to the longitudinal extent "f' of the link.
Referring to
Fig. 6, when a tire link mesh is assembled, each tire chain link contains one
ring
extending through its first aperture and a second ring extending through its
second aperture. The links are angled about 45 degrees to the direction of
rotation of the tire. Since each edge of the stud is preferably at an angle of
about
45 degrees to the longitudinal extent "I" of each link, two opposing stud
edges
end up being aligned perpendicularly to the direction of travel of the
underlying
tire thereby enhancing the gripping of the edges onto or into the ground. For
example, in Fig. 6, edges 38, 42 are perpendicular to direction of the tire
rotation
(edges 40, 44 are parallel to the direction of the tire rotation).
While the preferred embodiment illustrated herein shows three studs on each
tire
chain link, an embodiment using two studs or other numbers of studs is within
the
scope of the present invention.
The link and the studs may be integrally formed, preferably by forging to
avoid
zo the weakness of joints that may be caused by welding.
The pitch length of the link, namely the maximum distance between distal
inside
edges 46, 48 of the attachment apertures 12, 14 respectively is preferably
about
100 mm but may range from 85 mm to 115 mm.
The tire chain link of the preferred embodiment provides a combination of
advantages that result in a superior tire chain mesh that exhibits enhanced
traction and good tread protection as compared to prior art tire chain links
and
that is notably suitable for applications in forestry and in other
environments
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involving rough ground that may be combined with snow, ice and organic
materials.
It will be appreciated that in the foregoing specification, the invention has
been
described with reference to specific embodiments thereof. However, the scope
of the claims should not be limited by the preferred embodiments set forth in
the
examples, but should be given the broadest interpretation consistent with the
description as a whole. The specification and drawings are, accordingly, to be
regarded in an illustrative rather than a restrictive sense.
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