Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SUMMARY OF THE :CNVENTION
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Generally speaking, this invention relates to self-propelled
vehicles used primarily to transport long loads across roadless
terrain. More specifically, it relates to rubber tired vehicles
that have wheel suspension mechanisms which provide balanced
weight between its wheels and additionally permits adjustment of
the steady state position of the main bed frame of the vehicle
relative to a longitudinal roll axis to permit compensation for
the vehicle position when operating continuously on the side of a
hill, and also to facilitate unloading of the vehicle by a side
dumping action in either direction. ¦
In summary, the vehicle comprises an elongated bed frame
that forms the backbone of the vehicle. This frame is balanced
on the central portion of modular front and rear wheel assemblies,
preferably each having four quadrilaterally spaced wheels. The
quad wheel suspenslon system is designed to provide a freedom of
~I movement of each wheel about mutually perpendicular roll and
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pitch axes that are vertically spaced one above the other. The
`` quad wheel assemblies are pivotally mounted on the bed so as to
- 20 be movable about a roll axis which is parallel to and beneath the
longitudinal axis of the main frame element. On the lower or
pitch axis of each quad wheel assembly, two walking beam members,
each carrying a pair of steerable wheels, are rockably mounted in
a balanced relationship. Thus the walking beams may-rock about
the pitch axis of the quad wheel assembly while the quad wheel
assembly itself may pivot about the roll axis. A mechanical
interconnection, forming a specific improvement of this invention,
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o~pri=es A pair of tubular torque transmission members that
¦extend from one quad wheel assembly toward the other and are
interconnected by a novel linkage system which continuously
adjusts the position of the longitudinal bed frame about the roll i
axis to lie intermediate the positions of the quad wheel assemblies.
Additionally, the linkage incorporates two power extensible links
by which the steady state position of the longitudinal bed frame
member relative to the roll axis may be selectively determined by
the operator.
A modified form of this invention provides a parallelogram
linkage connection between the main pivot block of each quad
wheel assembly and a load carrying cradle pivotally mounted on
the main frame for vertical movement about a longitudinal axis.
A vehicle equipped with this combination of features has
numerous advantages over prior art off-road vehicles.
The advantages become more pronounced when the vehicle is
used for transporting long objects, such as trees having a length
of forty feet or more, over soft, broken or uneven ground. When
obstacles such as rocks, fallen trèes or ditches are encountered
by the vehicle embodying the suspension of this invention, its
wheel suspension maintains substantially equal loading on each
wheel. At the same time, the normal position of the bed frame
relative to the roll axis may be selectively adjusted to compen-
sate for continuous operation of the vehicle on the side of a
hill, and the same mechanism will effect a convenient unloading
of the vehicle by a tilting movement of entire bed frame toward
either side thereof.
Other advantages and objects will become more apparent when
the following description is read with reference to the accompanying
drawings.
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BRIEF DESCRIPTION OF DRA~INGS
Figure 1 is a side elevational view of a complete, vehicle
embodying the wheel suspension mechanism of this invention.
Figure 2 is a front elevational view of the vehicle of
Figure 1.
Figure 3 is a plan view of the vehicle of Figure 1.
Figure 4 is an enlarged partial perspective view of the
suspension mechanism for the quad wheel assemblies utilized in
the vehicle of Figure 1.
Figure 5 is an enlarged partial perspective view illustrating
the roll control linkage for the wheel suspensions incorporated
in the vehicle of Figure 1.
Figure 6 is a side elevational view, similar to Figure 1, of
~ a vehicle incorporating a modification of this invention.
,, Figure 7 is a plan view of Figure 6.
Figure 8 is an enlarged partial perspective view of the quad
wheel suspension system incorporated in the vehicle of Figure 6.
Figure 9 is a partial perspective view illustrating a
selected static position of the wheel supporting cradles and
frame of the vehicle for continuous operation along a hillside.
DETAILED DESCRIPTION OF INVENTION
The vehicle illustrated in the drawings is a transportation
vehicle such as one used for forwarding tree lengths,from a
harvesting area in a forest to a landing adjacent to a road.
Referring particularily to Figures 1 - 3 of the drawings, it will ,
i be seen that the vehicle 20 is comprised of an elongated bed
frame assembly 21 including load-carrying c,radle assemblies 22 `
adapted to carry a plurality of tree lengths 23. Front and rear
quad wheel assemblies 24, 26 are respectively attached to the bed
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frame assembly 21 by journals so as to be pivotally movable about
a longitudinal roll axis disposed parallel to and beneath the bed
frame assembly 21. A roll control linkage means 28 interconnects ;
the quad wheel assemblies with each other and with the elongated
bed frame assembly so as to control their relative positions
during operation over rough terrain. Preferably an engine unit
30 is located at the rear end of the vehicle, and an operator's
cab 31 is located at the front end. 1,
The illustrated bed frame assembly 21 comprises an elongated
bed frame element 32 extending lengthwise along the center line
of the assembly. The bed frame 32 which serves as the backbone
of the vehicle may be a rectangular tube. A plurality of rigid
bed cross beams 38 extend laterally outwardly from the bed frame
structure in both directions to form the load-carrying cradles
22. Upright side stakes 44 may be provided on the outer ends of
the cross beams. The stakes, along one or both sides, may be
releasably mounted to permit sidewise dumping of the load on
either side by appropriately tilting the bed frame assembly 21
about the roll axis of the wheel suspension assemblies.
In the drawings it will be noted that the front and rear
quad wheel assemblies 24, 26 are substantially identical to one
another~ so for the sake of brevity~ the similar portions will be
described with respect to one of them only. Accordingly, atten-
tion is directed to Figure 4 of the drawings wherein the details
of the front quad wheel assembly 24 are illustrated.
The suspension system for the front quad wheel assembly
includes a main pivot block 46 which is pivotally suspended
beneath the tubular bed frame 32 between a pair of depending
locks 32a, thus providing pivot 1 ~ovement about a longitudinal
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horizontal roll axis which is parallel to and slightly below the
axis of the tubular bedframe 32. Such pivotal mounting is not
shown but is entirely conventional. A torque transmission tube 94
, extends rearwardly from the main pivot block 46 and is co-movable
I therewith about the vehicle roll axis. A similar tube 95 extends
forwardly from the rear quad wheel assembly and the adjacent ends
I of tubes 94 and 95 are respectively interconnected by a roll
¦ control linkage mechanism 28 to be hereinafter described.
The bottom portion of main pivot block 46 is provided with a
pair of laterally projecting horizontal pivot pins 46a which
respectively provide pivotal mounting for a pair of walking beams
48 which are of identical configuration except that they are
mounted in reversed positions on the pivot pins 46a. Each walkins
beam 48 is of a generally truncated W-shaped configuration in pla
view including a central truncated inverted V-shaped portion 48a
defining the bearing for the pivotal mounting on pin 46a and
identical angularly disposed arcuate end elements 48b which provic e
¦ mountings for steerable wheel units 58 of the quad wheel assemblils.
; ¦ The horizontal angle of elements 48b determines the maximum wheel!¦ turning angle. The ends of arm portions 48b are bifurcated as
indicated at 48c and the bifurcated ends are traversed by a
vertical pivot unit 48d which pivotally supports a central
l cylindrical portion 50a of a wheel spindle housing 50. At its
; I outer end, the spindle housing 50 terminates in a power driven
cylindrical hub 50b to which a wheel 58 is rigidly secured in
conventional fashion. The inner end of housing 50 defines a gearl
chamber 50c plus a mounting flange 50d for mounting an electrically
or hydraulically driven reversible motor 54 by which the wheel 58;
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is driven. The gearing mechanism interconnecting the reversible
motor 54 with the wheel hub 50b may be entirely conventional and
need not be described in detail. The extreme inner end of wheel
spindle or drive housing 50 is provided with a pair of bifurcated
lugs 50e which pivotally mount the apertured end of a steering
actuator 56. The other end of actuator 56 is pivotally mounted
to the bottom portion 48e of the truncated W-shaped walking beam
48. While actuator 56 may be hydraulically operated, I prefer to
employ an electrically driv~n actuator and hence an actuator
motor 57 is mounted on the actuator 56 and effects the extension
or retraction of actuator 56 to in turn effec,t a steering motion -
of the associated wheel 58.
Within housing 50, a suitable power actuated brake (not
shown) is also provided.
From the description thus far, it should be apparent that
the steering movements of the wheels 58 about the respective
steering pin units 48d involve a much larger turning radius than
is customarily employed in wheeled vehicles. This '
large turning radius is of significant advantage in effecting a
lateral bodily displacement of the entire vehicle through the
combination of limited steering, braking and rotational movements¦
of the wheels in a selected sequence. Obviously, both the wheel I
driving motors 54 and the steering actuator motors 57 ~ust have
sufficient power to effect the desired rotation of the wheels and,
steering of the wheels under the very adverse conditions en-
countered in off-road operations. Such power may be supplied
from a generator (not shown) driven by engine 30.
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From the description thus far, it is also appàrent that each !
quad wheel assembly 24, 26 is suspended relative to the main bed
frame element 32 in such fashion that the bed frame may pivot
relative to the quad wheel assemblies about a roll axis which is
parallel to and slightly beneath the main bed frame element 32.
Concurrently, the wheels on each side of the quad wheel assembly
may freely move in a vertical plane about a transverse horizontal
pivot axis defined by the walking beam pivot pin 46a. Moreover,
due to the "W" shape of each walking beam 48, steering movements
of each of the wheels up to a thirty degree (30) angle may be
accomplished in either direction without interference with the
suspension, the main frame or load carrying cradles of the
~ vehicle.
- ~ The relative angular movement of the quad wheel assemblies
24, 26 with respect to each other and to the elongated bed frame
assembly 21 is regulated by a roll control linkage 28, centrally
located on the vehicle, that causes equal loading to be imposed
on each quad wheel assembly, and also causes the bed frame
assembly to be rotated proportionately, preferably one half the
total angular displacement between the front and rear quad wheel
assemblies, as exists at any one time. Angular displacement
between the quad wheel assemblies relative to the roll axis
obviously occurs during operation on uneven terrain or over
boulders. The ground under the front quad wheel assembly may be j
laterally and possibly oppositely inclined to the ground under
the rear quad wheel assembly, such as might occur while the
vehicle is traversing a ditch at an angle.
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Referring now to Flgure 5, the roll control linkage 28 will
be described in greater detail. The rearward end of torque tube
194 and the forward end of torque tube 95 are suitably journale'd
¦in a depending frame block 32m and are disposed in spaced co-
¦axially aligned relationship approximately in the center of the
¦elongated frame member 32. Immediately above and between the
¦ends of the torque tubes 94, 95, the base member 32 is provided
¦with a pair of upstanding pivot ears 32f which support a pivot
¦pin 32g which traverses the center portion of a transverse frame
¦tilt lever 33. On each end of frame tilt lever 33 a longitudinal
¦connecting lever 35 is mounted for pivotal movement about a
¦horizontal axis. Additionally, on each end of torque tubes 94
¦and 95 there are respectively rigidly secured primary transverse
¦actuating levers 96 and 97 and the ends of'these levers are in
¦genexal vertical alignment respectively with the ends of the
¦connecting levers 35. A plurality of links 37 are provided
¦respectively having their ends'connected by a universal joint
¦connection to the aligned ends of primary levers 96 and 97 and
¦the connecting levers 35, Thus, any pivotal movement of one of
¦the quad wheel assemblies 24, 26 relative to the other will
¦result in a pivoting movement of the associated primary lever 96,
97 which in turn effects a tilting movement of the main tilt
l control lever 33 to shift the position of the main frame 32
¦ approximately one half the amount of pivotal displacement of the
¦ quad wheel assembly relative to the roll axis. Thus a very
¦ effective control of the movements of the main frame about the
roll axis in response to much larger movements of the quad wheel
assemblies is achieved and, in effect, the pivoted lever connec-
tion control means 28 provides for balancing the effects of
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rotations of the two quad wheel assemblies in opposite directions
about the roll axis on the main frame assembly.
Concurrently the roll cont~ol linkage effects a transfer of
forces between the two quad wheel assemblies to equalize the
loading thereof during movements about the roll axis.
The modification of this invention heretofore described is
particularly useful in the hauling of trimmed lengths of trees
having a total length in excess of 60 feet. In some woodland
operations, particularly as practiced in Canada, it is more
10 desirable to employ an off-road vehicle for bringing out loads of
fresh cut whole trees. A load of this type does permit some
angular shifting of the load supporting cradles as the transportin~
vehicle navigates difficult terrain areas.
Referring now to Figures 6, 7, 8 and 9, there is shown a
15 moaification of this invention wherein the load supporting
cradles 22 are not rigidly secured to the elongated tubular frame
element 32, but instead comprise a transverse beam 39, which is
pivotally mounted to the top surface of the tubular bed frame 32. ¦
Such pivotal mounting is provided by a pair of upstanding ears
20 32b and a pivot pin 32c which traverses the cross-beam 39. Each
cross-beam 39 is effectively secured for co-movement with the
main pivot block 46 of the quad wheel assembly by a pair of
parallel links 40, each of which has a bifurcated end 40a,
pivotally connected by a transverse pin 40b to the cross-beam 39, ,
25 and the other end 40c pivotally connected between a pair of
bifurcated ears 46e provided on the main pivot block 46 and
traversed by a pivot pin 46f.
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It may be desirable to form the load supporting beams 39
with the outer ends inclined upwardly as shown at 39a in Figure
9, in order to provide additional clearance for the quad wheel
assembly. The important thing is that as each quad wheel assembly
moves about the roll axis to traverse the terrain, a corresponding
pivotal movement of the load supporting cradles is imparted by
virtue of the parallelogram linkage connection of the cross-beams
39 to the main pivot block 46. At the same time, the roll
control linkage 28 is still operative to effectively balance out
oppositely directed inclinations of the front and rear quad wheel
assemblies and thus reduce to a minimum the pivotal movements of
the tubular bed frame 32 about the roll axis.
The advantage of this construction is a significant reduction
in the height of the load carrying cradles relative to the main
frame, hence lowering the center of gravity of the load.
A further feature of this invention is the addition to the
roll control lever assemblage 28 of a pair of power actuated
stabilizing links which permit the operator to adjust the static
position of the tubular main frame 32 relative to the roll axis.
Referring to Figure 5, such links may comprise the power actuated
extensible elements 43 which are respectively connected between
the extreme ends of the tilt control lever 33 and the bifurcated
ends of lateral projections 32k, formed on a depending block 32m,
provided on the underside of the tubular bed frame 32. As the
one stabilizing link 43 is extended by the application of either
hydraulic or electric power thereto, the other link 43 is re-
tracted so that the net effect is as illustrated in Figure 9,
in that the load supporting cradles or cross-beams 39 are shifted
laterally and angularly with respect to the roll axis. Thus, the
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load may be maintained in a substantially horizontal position,
even though the vehicle is being operated continuously on a
hillside. This capability for adjusting the static angular
position of the load carrying cradles relative to the roll axis
provides additional stability to the vehicle and hence permits
l~rger loads to be safely carried along a relatively steep
hillside.
An extreme extension of either link 43 can effect the
dumping of the load on a selected side of the vehicle.
Modifications of the preferred embodiments of this invention
herein described and illustrated will be apparent to those
skilled in the art and it is intended that the scope of the
invention be determined solely by the appended claims.
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