Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to ground support
vehicles of the type used mainly for recreational use, and more
particularly to such a vehicle having a driven rear track.
Vehicles have been designed for use on snow and others
for use on unpaved ground and trails. Although some attempts
have been made to provide conversions so that a common power
source and basic frame can be used on both vehicles, none has
been successful both because of the complexity of the conversion
but also because of the cost. A further factor for some
purchasers is that vehicles capable of such conversion are not
particularly good in at least one of these modes, again due in
part to the conversion.
Attempts have also been made to provide off road
vehicles which are capable of use on rough terrain and which
will also carry the user over snow. Typically such vehicles
have three bulbous wheels with 2 single wheel at the front.
While thsy will perform adequately in light snow, they lack
directional stability and are consequently o~ limited use.
The present invention provides a novel form of vehicle
designed to be used both on snow and on unpaved ground. The
vehicle can be directed by a single ski or by a wheel as
desired. By contrast with prior art known to the applicant9 the
drive system can be used very successfully in many different
environments including snow, mud, sand, etc. The vehicle
handles like a motorcycle in all conditions and yet has
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distinctive characteristics ~naking it a unique ~nachine for
recreational use. This is achieved by providing the drive
system with an improved track having transverse cleats, the
peripheries of which are curved convexly across the width of the
track. The cleats are carried on a flat belt running on
rollers. Preferably a leading portion of the underside of the
track is inclined upwardly and forwards. These and other
aspects of the invention will be described with reference to the
following drawings in which:
Fig. 1 is a perspective view looking generally from the
front and side of a preferred embodiment of a ground support
vehicle embodying the present invention;
Fig. 2 is a cross-sectional view on line 2-~ of Fig. 1
and showing parts of the vehicle;
Fig. 3 is a cross-sectional view on line 3-3 of Fig. 1
showing a ski forming part of the vehicle;
Figo 4 is an exploded perspective view looking
generally from the rear and side and showing the track support
and drive arrangement of the vehicle;
Fig. S is a sectional view on line 5-5 of Fig. 4;
Fig. 6 is a perspective view of a section of track used
in the vehicle; and
Fig. 7 is a sectional view on line 7-7 of Fig. 6.
Reference is made firstly to Fig. 1 which illustrates a
vehicle having a frame 14 carrying a prime mover, a drive track
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assembly 12 coupled to the frame such that the prime mover can
drive the assembly to propel the vehicle. At its forward end
the frame is coupled to a conventional arrangement of motorcycle
forks 15 carrying a ski 10 for directing the vehicle over some
surfaces as will be described.
The front fork 15 has handle bars 16 and a pair o
shock dampers 17. As is conventional with such forks, it is
pivotable relative to the vehicle frame 14 and is used in this
vehicle to turn the ski 10 when steering the vehicle.
The shock dampers 17 are secured at their lower ends to
a pair of studs 19 proje~ting laterally from opposite sides of a
channel member 20 which, as can be seen from Fig. 2, is provided
at its upper end with a welded structure comprising a pair of
metal plates extending at approximately right angles to one
another. A pair of brackets 24 and 25 are secured to the outer
faces of the plates 22 and 23 and a pair of side plates 27 are
provided with a pair of bolt holes 28 and welded to opposite
sides of the channel member 20. The shock dampers 17 are
secured to the plates 27 by bolts 29 extending through the holes
28.
Returning to Fig. 1, the lower end of the channel
member 20 is secured by a pivot pin 30 to a bracket 31 mounted
on leaf springs 32 on the ski 10, and a rubber bumper 34 is
secured to the underside of the leaf springs 32 to provide some
shock absorption.
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The brackets 24 and 25 (~ig. 2) retain respective ends
of helical tension springs 36 and 37 which are also anchored at
brackets 3~ and 40. The bracket 39 is mounted on the ski 10 at
the front end of the leaf springs 32 and the bracket 40 is
secured to the rear end of the ski.
A bar 42 between the bracket 39 and the tip of the ski
provides a handle for manipulation of the front end of the
vehicle and also reinforces to toe of the ski.
Reference is next made to Fig. 4. An internal
combustion engine 44 is moun-ted on the vehicle frame 14 and
drives a clutch 46 through a drive belt 47. Clutch 46 has an
output shaft 48 which, through a pair of sprocke~s 49 and 50 and
a drive chain 51, drives a cross-shaft 52 forming part of the
drive track assembly 12.
As also seen in Fig. 4, the drive track assembly 12
includes a generally horizontal, rec~angular frame 54 which is
secured to the vehicle frame 14 for pivoting vertically about
its forward end. More particularly, a pair of forwardly
projecting arms 56 are welded to the front end of the horizontal
rectangular frame 54 for receiving therebetween a bracket S8
forming part of the vehicle frame 14. As better seen in Fig. 5,
this bracket carries bushings 60 for rota~ion on a sleeve 61
whicll in turn is mounted in the arms 56. This sleeve carries
bearings 62 which provide rotation for the cross-shaf~ 52
carrying sprockets 50 and 66. The sprocket 66 is connected by a
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drive chain 67 to a lower sprocket 68 on a shaft 69. This shaft
is also attached at its midpoint to a track drive sprocket 70
adapted to engage in holes 71 formed in an endless belt 72 (Fig.
1) which in use is in contact with the support surface to drive
the vehicle.
The shaft 69 at the forward end of the drive track
assembly is journalled in bearings 74, of which only one can be
seen in Fig. 4. These bearings retained by plates 75 depending
downwardly from integral lower shells 77 which are shaped to fit
against the underside of frame 54. Upper shells 78 also fit
against the frame and bolts 79 provide clamping engagement with
the horizontal frame 54, which is formed with longitudinal slots
80 to provide fore and aft adjustment fit tensioning the drive
chain 67 To this end adjustment bolt 81 is captured in a lug 82
welded to the frame 54 and is threadably engaged in a lug 83
depending from the lower shell 77.
A pair of front idler rollers 90 on the shaft 69 guide
the endless belt 72 at the front end of the frame 54, and a pair
of rear idler rollers 92 guide the endless bel~ 72 at the rear
~nd of the frame 54. The rollers 92 are mounted on a shaft 93
which is rotatably secured to the frame 54 in a manner similar
to that in which the shaft 69 is secured, and which will
therefore not be described in detail except to say that the
shaft 93 is not adjustable on the fra~e 54.
A pair of plates 94 depending from the underside of the
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horizontal frame 54 carry a sha~t (not shown) on which a pair of
roller assemblies indicated generally by reference numerals 96
and 97, respectively, are pivotally mounted and are biased
downwardly by means of a spring 97 to urge rollers 98 against
the upper surface of the lower run of the endless belt 72. This
gives the belt an upward incline between the roller assembly 98
and the rollers 90 as will be explained.
A saddle 100 is mounted at the rear end of the vehicle
frame 14, and a pair of shock dampers 101 are pivotally
connected to the vehicle frame 14 by pivot bolts 102 and to the
horizontal frame 54 through a pair of plates 104 projecting
upwardly from opposite sides of the horizontal frame 54 to damp
the pivotal movement of the track assembly 12 relative to the
vehicle frame 14 about the pivot bolt 60.
A metal plate llO (Fig. 1) is secured beneath the
vehicle frame 14 and the engine 44 for deflecting snow, ice, mud
and the like from the engine 44 and from the rider of the
vehicle, and a casing lll is mounted on the top of the drive
track assembly 12 for covering the top of the drive track.
As will be readily apparent from the drawings, the
vehicle illustrated in ~he drawings is intended to be ridden
somewhat in the manner of a motorcycle and, therefore, the
vehicle and the rider will lean sideways when the vehicle
travels around a curve. To counteract lateral slippage of the
ski 10 when the vehicle and the rider lean sideways in this
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manner, longitudinal ribs 112 (Fig. 3) in the form of metal rod
welded to the underside of the ski 10 are provided beneath the
opposite lateral edges o~ the ski lO, and a central rib 114,
also of welded metal rod, extends longitudinally of the
underside of the ski 10 and is equispaced from the ribs 112.
To facilitate driving engagement of the drive track 12
with the snow, ice or ground on which the vehicle is travelling~
the endless belt 72 is provided with a plurality of cleats 115
tFig. 6) which are spaced apart along the belt 72 and which each
extend transversely the entire width o the belt 72. To
facilitate the leaning of the vehicle and its rider, the height
of the cleats 115, in a direction perpendicular to the outer
surface of the belt 72, increases from opposite edges of the
belt 72 to the centre line thereof, so that cleats 115 present
an outwardly convex peripheral surface 116. Collectively, and
more generally, the cleats on the undersides of the track
combine to define a convexly-curYed track periphery.
Ribs 117 project outwardly from, and extend
transversely of the surface 166 for counteracting lateral
slippage oE the drive track. Also, as seen in Fig. 7, the
cleats have convergent front and rear faces 118, 119 so that as
the cleats pass around the Eront of the track and engage mud or
snow, they will take up the Fig. 7 positions as ~hey meet the
flattened portions of belt and this action will tend to squeeze
the mud and/or snow downwardly, free from the track. The action
is of course enhanced by the movement of the cleats as they pass
from the inclined forward portion of the track rearwardly to the
flat main portion.
Although shown with planar front and rear surfaces, in
general these faces will be acceptable provided that their shape
and general convergence satisfies the requirements to give a
self-chaining action. For this reason the term "convergent
faces" is intended to include curved as well as flat faces.
The frame 54 is in two parts, namely a rear part 120 and a front
part 121 and the two frame parts 120 and 121 are adjustably
displaceable relative to one another, by means of adjustment
units 123 in threaded engagement with the rear part 120, for
relatively displacing the rollers 92 and the rollers 90
longitudinally of the track assembly and thereby adjusting the
tension of the track and facilitating changing the belt.
It will be appreciated that the cleats on the track
give it a good grip in snow, mud and other soft or loose
surfaces. However it has been found that with very little
practice a person can drive around curves in such surfaces by
banking the vehicle and using the forward drive of the track in
combination with the ski to steer. In fact for demonstration
purposes, the vehicle has been driven hard in this form on paved
sur~aces without great difficulty.
The track also includes a forward portion ~previously
described) on the underside which is inclined upwardly. This
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also aids stability because as the vehicle moves forwards, the
track tends to drive out of the depression it creates in snow or
mud thereby tending to free itself rather than to cut further
into the snow.
In some conditions where the ground is hard or stony,
it may be preferred to make a simple modiication by
substituting a wheel for the ski to give better directional
stability. However it should be appreciated that the ability to
bank gives the vehicle good stability when cornering even with
the ski on ~uite hard ground.
Further modifications can be made to the preferred
embodiment without departing from the scope of the invention.
The track is sh~wn to include cleats which could be attached to
a belt or moulded into the belt. However the concept of an
endless belt is intended to include such analogous structures as
a chain having a short pitch or simply interconnected slats
which in cross-section resemble a chain.
