Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
Field of Invention
'This invention relates to an endless track for vehicles particularly designed
for providing good traction in travel over rough and soft terrains and
allowing for
easy track maintenance.
Background of Invention
Various forms of track-laying vehicles have been developed for use in
construction, exploration and transport in many oft road situations. Tracks
which have soft grouser or cleat were initially mainly developed far such
vehicles to allow at least occasional use on roadways so as to prevent damage
to
the road surface. Rubber cleats which could be temporarily attached to tracks
which were otherwise all metal have also been in use. It has become necessary,
due to government regulations, in travel over all terrain in certain areas,
such as
in northern regions, to avoid the use of endless tracks which have ground
engaging metal surfaces or cleats with the view of preventing what is
considered
to cause extensive and/or permanent damage to the terrain. As a result, in
extended use of vehicles in such areas, it is desirable to be able to replace
part of
the tracks which are subject to wear under such continued use with a minimum
of
disassembling of the overall track as is required in many track designs
utili:~ed in
the past. It is further necessary in tracks for use in such areas to provide a
track
which has an ability to self clean its ground engaging surface when
continuously
or frequently travelling in areas of soft soil conditions.
Summary of Invention
It is an object of the invention to provide a track of the endless belt type
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which has good self cleaning features.
A further object of the invention is to provide an endless track with a
wearable treads which are readily separable from their related grouser bars
for
ease in replacement.
According to one aspect of the present invention there is provided a
vehicle endless track of the type having a pair of parallel continuous
flexible
belts extending in a longitudinal direction of the track, and a plurality of
longitudinally spaced grouser bars which extend transversely in relation to
the
longitudinal direction of the track. The track further includes a plurality
oil
ground engaging treads wherein each tread has a first elongated portion
thereof
underlying a portion of a first one of the grouser bars and at least one
second
adjoining portion underlying a portion of a second one of the grouser bars
adjacent to said first grouser bar.
More specifically, the present invention resides in a tread for use on a
vehicle endless track of the type having a pair of longitudinally extending
belts
separated by a central space disposed between inner opposed edges of the
belts,
the belts defining upper surfaces and lower ground engaging surfaces extending
laterally outward from their inner edges to outer edges thereof. trouser bars
are spaced in the longitudinal direction of the belts, and are elongated in a
transverse direction relative to the belts. The grouser bars have a central
section
spanning the central space between the belts and including portions engaging
the
upper surfaces of the belts on either side of their inner edges. The grouser
bars
each have outer end sections contiguous with the central section thereof and
projecting toward the outer edges of the belts. The tread of the invention has
a
central section and a pair of extended sections contiguous with opposite ends
of
the central section. The central and extended sections of the tread define a
lower
ground engaging surface of the tread. 'hhe central section of the tread
further
defines an upper surface facing the central section of an associated one of
the
grouser bars spanning the central space between the belts, and the central
section
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of the tread has portions engaging the lower ground engaging surfaces of t:he
belts beneath the portions of the central section of the above indicated one
of the
grouser bars engaging the belts on either side of the central space between
the
belts. The extended sections of'the tread which also have upper belt engaging
surfaces, continue obliquely from the central section of the tread and provide
outer end portions which underlie the outer end portions of a second one of
the
grouser bars adjacent to the above indicated one of the grouser bars.
More specifically, first fastener means rnay project upwardly from the
upper surface of the central section of the tread for reception in aligned
openings
in the belts at either side of the space therebetween and through aligned
openings
in the one of the grouser bars tc~ thereby provide attachment together of the
central portion of the tread, the belts and the said one of the grouser bars.
Moreover, there may be provided second fastener means projecting
upward from the outer end portion of the extending sections of the tread for
1 S reception in aligned openings in the belts and in the outer end portions
of the
second of the grouser bars adjacent to the said one of the grouser bars.
Preferably, the central section of the tread is provided with openings in the
portions thereof for engaging the lower ground engaging surfaces of the belt
at
either side of the central space, the openings being located for reception of
common fastening means received in aligned openings in the belts and the
associated one of the grouser bars to thereby provide attachment together of
the
tread, belts and the associated one of the grouser bars.
Moreover, preferably the outer end portions of the extended sections ot~
said tread is further provided with openings for reception of additional
common
fastenings means received in aligned openings of the belts and in the outer
end
portions of the above indicated second one of the grouser bars to thereby
provide
attachment together of the tread, belts and the second one of the grouser
bars.
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Brief Description of Drawings
Figure 1 is a perspective view of a vehicle track as mounted on wheels of
a tracked vehicle and including treads in accordance with one embodiment of
the
present invention;
Figure 2 is an exploded lower perspective view of a portion of a lower run
of the track illustrated in Figure l;
Figure 3, is a lower perspective of a tread of the embodiment of the
invention introduced in Figure l and one related grouser bar;
Figure 4 is a bottom view of a section of vehicle track from a lower run of
the track as shown in Figure 1;
Figure 4A is a sectional view of the assembled track as seen from line A--
A of Figure 4;
Figure 4B is a sectional view of the assembled track as seen from line B--
1 S B of Figure 4;
Figure 5, which appears on the same sheet of drawing as Figure 3, is a
perspective view similar to Figure 3, but of an alternative embodiment of the
tread and a related grouser bar of the present invention;
Figure 6 is a bottom view of a section of a lower run of a track
?0 incorporating the tread shown in Figure S;
Figure 6A is a cross sectional view of the track shown from the line A--A
of Figure 6; and
Figure 6B is a cross sectional view of the track seen from the line B--B of
Figure 6.
Detailed Description of Invention
In Figure I, the reference number 10 generally denotes a track
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incorporating the invention, the track 10 being shown as mounted on wheels 1 I
of a track laying vehicle (not shown). A lower run 12 of the track supports
the
weight of the vehicle from wheels 12, and the engagement of the lower run 12
with the ground surface provides a driving force to the vehicle through a
drive
sprocket or as shown in the case of the embodiment of Figure 1, a drive wheel
13.
The track 10 includes a pair of continuous belts I 4,14, which extend in the
longitudinal direction of the track. Each of the belts 14,14, as shown, is
flexible,
normally being formed of reinforced rubber belting each defining an upper
surface 15, and a lower ground engaging surface 16. The belts 14,14 are
parallel
and are separated by a central space 17 between opposed inner edges 20,20
thereof. 'The ground engaging surfaces 16 of the two belts, which extend
laterally outward from the inner edges 20,20 to outer edges 21,21 of the belts
are
relatively large so as to provide for a relatively low ground bearing
pressure.
The belts 14,14 are joined by a plurality of rigid members shown as
grouser bars and generally denoted with the reference number 22. The grouser
bars 22 extend transversely relative to the longitudinal direction of the
overall
track 10, and are elongated members equally spaced in the longitudinal
direction.
As viewed in the lower run 12 of the track, the grouser bars 22 are located on
the
upper surface 15,15 of the belts 14,14. Located below the belts 14,14, as seen
for the lower run 12, are a plurality of treads of the present invention,
generally
denoted with the reference number 23, the number of the treads 23 being equal
to the number of the grouser bars 22, but each tread 23 is associated with two
adjacent grouser bars 22, as described further below. Affixed to an upper
surface
24 of each grouser bar, again as viewed in the lower run 12, and centrally
located thereon, is a wheel guide means 25, as will also be described in more
detail below. The particular relationship between the grouser bars 22 and the
treads 23, which is an important aspect of the invention, is repeated
continuously
along the length of the track 10, and in describing this relationship and the
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manner in which the parts of the track 10 are assembled, reference is made
more
specifically to two adjacent grouses bars 22a and 22b and two adjacent treads
23a
and 23b in Figures 2 and Figures 4 to 4b.
In the embodiment of the invention shown in Figures 1, 2, 3 and 4 to 4b,
the grouses bars 22 are formed of flat bar stock of rectangular cross so as to
provide flat upper and lower surface of a width substantially equal to the
width of
the treads 23, and the length of each grouses bar 22 is substantially equal to
the
distance between the outer side edges 21,21 of the two belts 14,14 when the
track
is assembled. With particular reference to Figure 3, each of the grouses bars
10 22 has central section 26 spanning central space 17 between the belts
14,14, this
central section of each grouses bar 22 being of sufficient length to provide
opposite ends portions containing opening 27, and defining lower surfaces
30,30
for engaging the upper surfaces 15,1 S of belts 14,14 adjacent either side of
the
central space 17. Outer end sections 31,31 of the grouses bars 22, which
further
project towards the outer edges 21,21 of the respective belts 14,14, each are
provided with a pair of openings 32,32.
Each of the treads 23 is forced of an abrasion resistant elastomeric
material such as one formed by a molding technique and provides a lower ground
engaging surface 34. As best seen in Figure 3, each tread 23 includes a first
portion which extends transversely relative to the longitudinal direction of
the
overall track 10, this first portion providing a central section 33 which is
of
sufficient length to also span the central space 17 between the belts 14,14
and to
extend at opposite ends thereof beneath the lower ground engaging surfaces
16,16 of the pair of belts 14,14. The central section 33 of each tread 23
provides
an upper surface 35 which engages the ground engaging surface 16 of the belts
14, 14 at opposite sides of the central space 17 when assembled. The outer
parts
of the central section 33 of the tread which engage the belts each are
provided
with countersunk holes or openings 36 which, as will be described further
below,
are spaced to align with openings 27,27 in the outer end portions of the
central
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section 26 of the grouser bars 22. Contiguous with opposite ends of the
central
section 33 of each tread 23 are adjoining portions of the tread 23 formed by
extended sections 37,37. In the embodiment illustrated in Figures 1 to 4b,
each
extended section 37 includes an intermediate portion 40 which extends
obliquely
relative to the transverse direction of the central section 33 and a
continuing outer
end portion 41. The two outer end portions 41,41 of each tread lie on a common
axis extending parallel to but spaced from an axis of the central section 33
of the
same tread, the distance in the longitudinal direction ofthe track between the
axis
of the central section 33 and the common axis of the related outer end
portions
41,41 being equal to the distance in the longitudinal direction of the track
between the central axes of adjacent grouser bars 22. Each of the extended
sections 37,37 are provided with upper surfaces 42 for engagement with the
lower ground engaging surfaces 16,16 of the belts 14,14. The outer end
portions
41,41 are each provided with a pair of countersunk openings 43 which are
positioned and spaced to align with the opening 32 located near the outer ends
of
the grouser bars 22. Preferably the edges of the ground engaging surface 34 of
each tread are beveled as indicated at 39. As previously indicated, the treads
23
are formed of solid, tough elastomeric material, and preferably metal inserts
48
are embedded in the material to enhance the strength and wear characteristics
of
?0 the treads. Such inserts 4~ are shown in the central section of the tread
and are
also particularly desirable in the area surrounding holes 36 and 43 as can be
seen
in Figures 4A and 4B. For reasons which become apparent below, it is desirable
that the obliquely extending intermediate portion 40 of the tread remains the
most
pliable part of the tread.
As may be noted, the belts 14,14 are provided with a series of aligned
openings transversely across them at each location of a grouser bar (see line
a
and line b in Figure 2).. Each belt has an opening 44 adjacent its inner edge
20
far alignment with the openings 27 of the central section 26 of each grouser
bar
22. A pair of openings 45 are provided toward the outer edge 21 of each belt
and
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are located to align with the pair of openings 32,32 in the outer ends 31,31
of
each grouser bar 22.
The wheel guide means 25 as shown for the embodiment of the invention
illustrated in Figures l, 2, 4A and 4B consists of a single metal unit 46
having a
flat bottom surface 47 for engagement with the upper surface of the central
section 26 of the grouser bar 22. A central portion 50 of the wheel guide unit
46
has a flat upper surface 51 of the approximate length of the space 17 between
the
belts 14,14. Raised side parts 52,52 of the wheel guide unit 46 slant upwardly
and outwardly from the flat upper surface 51. Vertical openings 53 extend
through the raised side parts 52,52 and are located to align with openings 27
of
the grouser bars.
In the assembling of the track 10 as shown in the above described
embodiment six bolts 54 and 55 and associated nuts 56 are utilized for each
tread
23, two pairs of bolts 54 being inserted from the bottom of the tread through
the
two pairs of countersunk openings 43 in the outer end portions of the tread,
and
one pair of bolts 55 of longer length being inserted from the bottom of the
tread
through the countersunk openings 36 in the central section of the tread. The
two
bolts 55 passing through the openings 36 in the central section 33 of the one'
tread 23a also pass through the openings 44,44 of the two belts 14,14 on
transverse line a in Figure 2, then through holes 27a,27a of one grouser bar
22a,
and then through openings 53,53 of a wheel guide unit 46. The nuts 56,56 are
threaded onto the bolts 55,55, thus clamping the tread 23a, belts 14,14,
grouser
bar 22a and wheel guide unit 46 together with the upper surface 35 at the
outer
ends of the central portion 33 of the tread 23a engaging the lower surfaces
16,16
of the belts 14,14 on either side of the central space 17. The bolts of the
two
pairs of bolts 54,54, which pass through the openings 43a,43a in the outer end
portions 41 of the tread 23a also pass through the openings 45,45 of the belts
14,14 on the transverse line b in lvigure 2, and then through the opening
32b,32b
of a second grouser bar 22b, which is the grouser bar next adjacent the
grouser
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bar 22a. The two pairs of nuts 56,56 are threaded on to two pairs of bolts
54,54,
thus clamping the tread 23a, belts 14,14, and grouser bar 22b together with
the
upper surfaces 42 of the extended sections 37,37 engaging against the lower
surfaces 16,16 of the belts 14,14. It can be further seen that on clamping the
next
tread 23b to the belts, the bolts 55,55 which pass through the holes 32b,32b
of
the next grouser bar 22b, there is clamping of the central section 33 of that
tread
to the central section 26 of the grouser bar 22b on the transverse line b
shown in
Figures 2, which is a common transverse axis on which the holes containing the
bolts 55 pass through the openings 43a of the tread 23a. It is therefore also
to be
1 o noted that while the central section 33 of tread 23a underlies the central
portion
26 of a first one of the grouser bars 22a, the outer end portions 41,41 of the
same
tread 23a underlie the outer end sections of a second grouser bar 22b which is
adjacent to the first grouser bar 22a. The relationship is of course repeated
in
that as seen in Figure 2, for example, while the central section 33 of the
tread 23b
underlies the central section 26 of the second grouser bar 22b, the outer end
portions 41,41 of that tread 23b underlies the outer end sections 31,31 of a
third
grouser bar 22c which is next adjacent to the second grouser bar 22b in the
series
of subsequent grouser bars 22a, 22b, 22c, 22d, etc.
A purpose of the holes 36 and 43 being countersunk is that the heads of
?0 the bolts 54,55 are well above the lower surface 34 of the tread so that
substantial
wear of the tread may occur without the heads of the bolts becoming exposed.
It
will be appreciated that as an alternative to bolts 54,55 being provided
separate
from the tread 23, they may be molded into the tread and thus are fixed in
position to project from the upper surface of the tread in positions to align
with
the holes in the belts, grouser bars and wheel guides as the tread is brought
into
position for attachment to the track on replacement as is described in more
detail
below.
Referring to the embodiment of the track 10' illustrated in Figures 5, 6, 6A
and 6B, it can be seen that the basic principle of the structure is similar to
that of
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the earlier described embodiment of the track 10. Other than for the spacing
of
the bolt holes 44, 45 & 45 across the belts, which are substantially equally
spaced in the second embodiment, the belts 14, 14 may be as previously
described. The grouser bar 22' of the second embodiment of the track 10',
unlike
the flat shape of the grouser bar' 10, has the middle portion 59 of the
central
section 26 thereof thicker and more of a circular cross section in order to be
compatible with a sprocket drive (not shown). 'the middle portion 59 of
substantial circular cross section is somewhat depressed below the lower
surfaces
30', 30' of the outer end sections 31',31', The outer end sections 31', 31'
are of a
flatter nature than the mid portion 59 tapering slightly in thickness towards
their
extreme outer ends. As in the case of the bolt holes in the belts the spacing
between the three holes 32, 32', 27 may be substantially equal in the
transverse
direction.
The tread 23' of the second embodiment has a central section 33' which
I 5 may have a slight trough 60 in its upper surface extended in the
longitudinal
direction of the track 10'. In the assembled condition of the track, the
trough 60
receives the depressed middle part 59 of the grouser bar 22' between the belts
14,14. In the second embodiment as shown, the central section 33' of the tread
23' has somewhat greater length than in the previous embodiment and in the
area
?0 it joins the oblique sections 37', 37', countersunk holes 43' are provided
for
alignment with holes 32' of the grouser bars 22'. The sections 37',37' do not
include additional end sections like those which are parallel to the central
section
of the tread 23 of the earlier embodiment, but rather the extended section 3?'
continues obliquely to an end section 41' which terminates adjacent the outer
25 edges of the pair of belts 14,14. The end sections 41', 41' of the treads
23'
contain openings 43, which align with the outermost holes 45 of the belts and
the
outermost hales 32 of the grouser bar. As indicated in Figures 6 and A, the
end
section 41a' and 41a' of the tread 22a' which when assembled, underlie the
outer
end sections 31 b', 31 b' of the grouser bar 23b' next adj acent the grouser
bar 22b'
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under which the central section 33a' of that same tread 23a' underlies. And
again
while the central section 33b' of the tread 23b' underlies the central portion
of the
grouser bar 22b', its end section 41 b',41 b' underlies the outer ends of the
yet next
adjacent grouser bar 22c. In the embodiment shown in Figures A and 6B, it may
be denoted that unlike the wheel guide unit 46 of the first embodiment, the
wheel
guide means of the second embodiment consists of two parts 46', 46' so as to
leave the central portion of the grouser bar 22' exposed between the belts
from
inside of the track 10' for engagement by the drive sprocket of the vehicle.
Each
part 46' is provided with two aligned openings fox reception of the long bolt
55
and the most inner bolt 54 of the outer pair of bolts 54,54. As in the case of
the
wheel guide unit 46, the pair of parts 46',46' provide raised side portions
52.',52'
for guiding engagement with the wheels 11 of the vehicle.
The treads 23 and 23' described in relation to the above embodiments,
because of their particular configuration, provide for uninterrupted contact
of the
consecutive treads with the ground surface, and thus provide for a quiet and
smooth ride of the vehicle, particularly when travelling over hard surfaces.
While treads of the tracks are exposed to the most significant wear of any
parts
of the tracks, they are capable of relatively inexpensive production and the
design
of the track permits individual replacement of the treads with a minimum of
disassembling of any other parts of the track. It may be noted to remove a
tread,
six bolts are removed, the two bolts 54 and the two pair of bolts 55,55.
However, since bolts 55 of one tread pass through a different grouser bar than
bolts 54 of the same tread, in the first embodiment, for example, the two
grouser
bars 22 with which the one tread is associated remain attached to the belts,
the
first still being attached by the outer bolts 54 and the second still being
attached
by the inner bolts 55. A new tread can then be attached by replacing the six
bolts.
In operation in soft ground conditions the treads provide good traction as
well as good self cleaning characteristics in view of the configuration
including
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the oblique sections of each tread which extends between two adjacent grouser
bars. While the lower run of the track is in ground engagement, the axis of
the
central section and the axis through outer ends of the oblique portions of
each
tread are in a common horizontal plane, but as the track rounds the drive
sprocket
or idler wheel at opposite ends of the lower run, the oblique portions
experience
some flexing as the first axis leaves the common plane.
While two different embodiments of the invention have been illustrated
above, other modifications within the spirit of the invention as defined in
the
appending claims will be apparent to those skilled in the art.
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