Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION
BELT OVER MID-ROLLERS
FIELD OF THE INVENTION
[0001] The present invention relates to tracks for an industrial,
agricultural or a recreational vehicle. More specifically, the present
invention is
concerned with a wheel structure driven by a first endless track belt and
comprising a second track belt over mid-rollers.
BACKGROUND OF THE INVENTION
[0002] The propulsion system found on heavy-duty vehicles as well
as on tracked recreational vehicles such as snowmobiles for example
comprises longitudinally spaced apart wheel structures driven by an endless,
substantially inextensible belt having an inner surtace and an outer surface.
The inner surface is provided with a series of longitudinally spaced members
for guiding the track relative to driving and tracking wheels forming part of
the
wheel structures. The outer surface of the belt is formed of a plurality of
longitudinally spaced tread members that provide traction to the vehicle when
travelling on various ground conditions.
[0003] The wheel structures typically comprise a driven wheel and
an idler wheel, with a series of supporting mid-rollers.
[0004] The endless belt engages the necessary supporting wheels
such as drive and idler wheels or rollers. A recurrent problem relates to the
wear out of the mid-rollers.
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[0005] Typically, the mid-rollers are made of steel and protected with
a layer of rubber, which proves to have a chunking problem and an overall
reduced lifetime as well as providing a limited protection efficiency against
rocks penetration to the track. Another solution also contemplated is the use
of
steel scrapers to clean off any debris so as to prevent them to be ingested
between the track inner surface and support surfaces of the wheels of the
improved wheel structure.
[0006] US patent no. 6,299,264 discloses a solution for protecting
the mid-rollers of an endless track laying work machine by a heat shield
positioned between guide blocks of the endless track and an inner shoulder of
the mid-wheel.
[0007] There is still a need in the art for an improved wheel
structures driven by an endless track belt.
SUMMARY Of THE INVENTION
[0008] In accordance with the present invention, there is provided a
wheel structure for a heavy duty track propelled vehicle driven by a first
belt
tensioned around a drive wheel and an idler wheel, comprising a plurality of
supporting mid-roller wheels between the drive wheel and the idler wheel; and
a second track belt tensioned around the plurality of mid-rollers, the second
track belt being driven by friction therewith.
[0009] Other objects, advantages and features of the present
invention will become more apparent upon reading of the following non-
restrictive description of embodiments thereof, given by way of example only
with reference to the accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the appended drawings:
[0011] Figure 1 is a side-view of a wheel structure according to an
embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0012] Referring to Figure 1, there is shown a wheel structure,
generally denoted 10, which may be found on each opposite side of a chassis
of a heavy duty track propelled vehicle for example (not shown). The structure
usually includes a drive wheel 12 and an idler wheel 14 included within a loop
defined by a track or belt 18. Traction of the vehicle is achieved by a high
frictional engagement of the belt 18 with the drive wheel 12.
[0013] The belt 18 typically comprises an endless elongated body
made of polymeric material having a ground contacting outer surface 20 and an
inner surface 22. The core of the belt 18 may be reinforced as is
conventionally
known in the art.
[0014] The inner surface 22 comprises a series of longitudinally
spaced guide lug members 23, which are adapted to provide guiding of the
track 18 on undercarriage.
[0015] A plurality of supporting mid-roller wheels 16 is provided
between the drive wheel 12 and the idler wheel 14, each mid-roller-wheel 16
comprising a solid rim.
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[0016] A second track belt 30 is tensioned around the plurality of
mid-rollers 16, and is driven by friction therewith. The second track belt 30
is
guided by guide lugs 32 provided on an inner surface thereof, by engagement
with the mid-rollers 16.
[0017] The second track belt 30 allows a long lasting contact with
the guide lugs 23 of the inner surface 22 of the track 18, and allows a great
reduction of wear of the track 18 and of the mid-rollers 16, due to an equal
relative speed between the second track belt 30 and the guide lugs 23 of the
track 18.
[0018) The second track belt 30 may be made of the same material
than the belt 18. It is typically made of rubber and composite.
[0019] It is found that the second belt 30 provides a long lasting
protection against flowable debris ingested between the track 18 inner surface
22 and support surfaces of the mid-rollers 16, which may have an abrasive
action on the wheels of the drive structure, and therefore a damaging impact
on
the carcass life of the track 18. Consequently, the life times of the mid-
rollers
16 and of the track 18 as a whole are increased.
[0020] It is to be noted that the second track belt 30 may be easily
replaced without removing the mid-rollers 16.
[0021] Although the present invention has been described
hereinabove by way of embodiments thereof, it may be modified, without
departing from the nature and teachings of the subject invention as described
herein.
