Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SPLIT WALKING BEAMS FOR RAISING AND LOWERING RESPECTIVE SIDES
OF A VEHICLE OR IMPLEMENT FRAME TO CONTROL A TILT ANGLE OR
HEIGHT THEREOF
FIELD OF THE INVENTION
The present invention relates generally to vehicles or implements
employing walking beam assemblies each having a front wheel and rear wheel
carried adjacent opposite ends of the walking beam on opposite sides of a
pivot point
thereof, and more particularly to a split walking beam assembly in which the
conventional single-beam is replaced is replaced with a multi-piece beam
assembly
with front and rear beams that are pivotal relative to one another by an
actuator,
whereby changing the angle between the front and rear beams lifts or lowers
the main
pivot of the walking beam to adjust the height of the respective side of the
vehicle
frame.
BACKGROUND
It has previously been proposed in the prior art to provide a towed
ground leveling or ground scraping implement in which a tilt angle of the
scraper
blade about a longitudinal fore-aft axis of the implement is adjustable by
raising and
lowering a side of the frame at an outboard location spaced laterally outward
from a
longitudinal mid-plane in which the fore-aft axis is located.
Such an implement is disclosed in U.S. Patent No. 4,055,222, in which a
single wheel is provided at each side of a frame that is situated behind a
scraper
blade carried on a pull tongue of the towable implement. On one side of the
frame,
the axle of the respective wheel is attached to an inner one of a pair of
telescopically
nested tubes that stand upward from the frame, and an upright hydraulic
cylinder has
its respective ends coupled to the vehicle frame and the top end of the inner
tube,
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whereby extending the cylinder raises the inner tube in order to lift the
respective
wheel relative to the frame, thereby lowering the respective side of the frame
to tilt the
respective end of the blade downwardly toward the ground relative to the
opposing
end of the blade.
U.S. Patent 4,189,009 discloses another tilt-adjustable scraper with a
single wheel on each side of the frame. In this reference, a single axle
carrying the
two wheels is pivotally coupled to a rear end of a frame disposed behind the
scraper
blade for relative pivoting between the axle and frame on a pivot axis
residing in the
central fore-aft longitudinal plane of the implement. A hydraulic cylinder has
one end
coupled to an upright bracket at the center of the axle, and the other end
coupled to
an outboard point on the frame, whereby extension and collapse of the cylinder
tilts
controls a tilt angle of the axle relative to the frame and blade in order to
adjust the
blade angle relative to the ground.
U.S. Patent 2,734,293 also discloses another example of a tilt-
adjustable scraper with a single wheel at each end of an axle that is
pivotally coupled
to the frame for hydraulically actuated movement between the frame and axle
about a
tilt axis.
U.S. Patent Application Publication 2012/0311894 discloses another
example of a tilt-adjustable scraper with a single wheel at each end of an
axle or
subframe that is pivotally coupled to the main frame for hydraulically
actuated
movement relative thereto in order to set the blade angle.
A potential drawback of the forgoing prior art is that, because the towed
frame is carried only by a single wheel on each side of the frame, a rock or
other
ground protrusion in the path of either wheel will raise the frame and blade
by the full
height of the rock as the wheel rides overtop of same. It is known that the
use of
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walking beam axles can reduce the effective of such ground deviations, where
front
and rear wheels carried at respective ends of a beam pivotally coupled to the
frame
can 'walk' over such an obstacle, as the front wheel can ride at least
partially over the
obstruction before the rear wheel reaches the obstruction.
However, the prior art provides no teaching or suggestion of how to
implement a walking beam in a setting in which the wheel position is also to
be
controlled relative to the frame for use in controlling a tilt angle of the
blade.
The forgoing prior art implements each move at least one of the wheels
relative to the frame of the implement in order change the tilt 'angle of the
frame to
which the blade is attached. In each of the above cases, the blade and frame
are
pivotally connected for relative movement about a transverse axis to raise and
lower
the blade relative to the frame, but the blade and frame remain in a matching
orientation with one another relative to the tilt axis.
Another group of adjustable-tilt scrapers have fixed wheel axles that do
not move relative to the frame, and instead employ a mechanism for tilting the
blade
relative to the frame. Examples of such scrapers are disclosed in U.S. Patents
2,284,550; 2,520,266; and 2,883,777.
In addition to the forgoing references concerning towed scraper
implements, Applicant is also aware of U.S. Patent Application Publication
2012/0239258, teaches a self-propelled grader which employs a gyroscope
together
with blade slope and blade tilt sensors to monitor the blade position and
automatically
adjust same.
As these references adjustment the blade relative to the frame instead
of adjusting the wheels relative to the frame, they also lack any teaching or
suggestion of how to combine the advantages of a walking beam arrangement into
a
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blade-tilting arrangement relying on controlled movement between the frame and
wheels.
Applicant has developed an adjustable height walking beam solution
that can be employed on the frame of a scraper implement to address the
identified
shortcoming of the prior art, and that can also be employed to advantageous
effect on
other vehicle or implement types.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a vehicle or
implement comprising:
a frame situated having opposing sides disposed on opposing sides of a
longitudinal plane that runs in a longitudinal direction of the vehicle or
implement;
a pair of wheel assemblies, each being attached to the frame adjacent a
respective one of the opposing sides thereof so as to reside on and rollably
carry a
respective one of the opposing sides of the longitudinal plane, at least one
of the
wheel assemblies comprising:
a split walking beam assembly pivotally coupled to the frame for
pivotal movement of the split walking beam assembly about a first walking beam
pivot
axis lying transversely to the longitudinal direction, the split walking beam
assembly
comprising:
a front beam having front and rear ends spaced apart in
the longitudinal direction; and
a rear beam having forward and rearward ends spaced
apart in the longitudinal direction, the front end of the front beam being
situated
forwardly of the forward end of the rear beam in the longitudinal direction,
the
rearward end of the rear beam being situated rearwardly of the rear end of the
front
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beam in the longitudinal direction, the front and rear beams being coupled
together
adjacent the rear and forward ends thereof, and the rear beam being pivotal
relative
to the front beam about a second walking beam pivot axis lying transversely of
the
longitudinal direction;
5 a
front wheel rotatably coupled to the front beam adjacent the
front end thereof;
a rear wheel rotatably coupled to the rear beam adjacent the
rearward end thereof; and
a wheel assembly actuator coupled between the front and rear
beams of the split walking beam assembly and operable to pivot the front and
rear
beams relative to one another to adjust an angle measured between the front
and
rear beams at an underside thereof, whereby an increase of the angle lowers
the
respective side of the frame and respective lateral end of the blade and a
decrease of
the angle raises the respective side of the frame and the respective lateral
end of the
blade.
In one embodiment, there is provided:
a tongue having fore and aft ends spaced apart in the longitudinal
direction;
a hitch connector at the fore end of said tongue for coupling of the hitch
connector to a hitch of a towing vehicle;
a ground working arrangement coupled to the tongue adjacent the rear
end thereof with opposing lateral ends of the ground working arrangement
disposed
on opposing sides of the longitudinal plane of the vehicle or implement at
outboard
positions spaced laterally from said longitudinal plane;
wherein the frame is situated behind the ground working arrangement in
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the longitudinal direction, whereby increasing the angle of each wheel
assembly
lowers the respective lateral end of the ground working arrangement and
decreasing
the angle raises the respective lateral end of the blade of the ground working
arrangement.
Preferably there is provided:
a pivotal connection between the frame and the ground working
arrangement that allows relative pivoting between the frame and the ground
working
arrangement about a pitch axis that lies in the transverse direction; and
a pitch actuator coupled between the frame and the blade and operable
to tilt the ground working arrangement relative to the frame about the pitch
axis.
Preferably the frame comprises a cross-member lying transversely to
the longitudinal plane and a pair of rearward reaching frame members extending
therefrom in the longitudinal direction adjacent opposing ends of the cross-
member on
the opposing sides of the longitudinal plane, each rearward reaching frame
member
having a respective one of the wheel assemblies connected thereto and split
walking
beam assembly being pivotally connected to the respective rearward reaching
frame
member.
Preferably the rearward reaching frame members are respectively
connected to the cross-member at opposing ends thereof, and each extend
forwardly
past the cross-member to attach to the ground working arrangement.
In one embodiment, the ground working arrangement comprises a
scraper blade lying transversely of the longitudinal plane with opposing ends
of the
blade defining the lateral ends of the ground working arrangement on the
opposing
sides of the longitudinal plane.
Preferably the wheel assemblies both comprise a respective walking
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beam assembly, and the walking beam assemblies are arranged to be adjustable
into
different respective angles, thereby adjusting an angular position of the
frame about a
roll axis that extends in the longitudinal direction.
Preferably there is provided a control system operable to control
movement of the wheel assembly actuators.
Preferably the control system is arranged to automatically extend one of
the walking beam actuators while collapsing the other, thereby increasing the
angle
between the front and rear beams of one walking beam assembly while decreasing
the angle between the front and rear beams of the other walking beam assembly
so
as to raise one side of the frame while lowering the other side of the frame.
Preferably, each walking beam actuator comprises a hydraulic cylinder
with a respective extension port and respective retraction port;
the control system comprises a four-way, three-position, spring centered
directional valve with a pressure port for coupling to the output of a
hydraulic pump, a
return port for coupling with a hydraulic fluid reservoir, and a pair of
output ports
connected to either the extension ports or the retraction ports of the walking
beam
actuators; and
a hydraulic connection line coupling together the other of the extension
ports or the retraction ports of the walking beam actuators.
Preferably the directional valve is a double solenoid directional valve
arranged to use electronic signals to control a position of the valve.
Preferably there is provided a monitoring system arranged to monitor an
orientation of the frame about a longitudinal axis, and linked to the control
system to
automatically control the walking beam actuators and adjust the orientation of
the
frame.
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Preferably the first walking beam pivot axis and second walking beam
pivot axis of each wheel assembly are coincident with one another.
Preferably the first and second beams of each wheel assembly both
pivot about the second walking beam pivot axis.
According to a second aspect of the invention, there is provided a
method of providing tilt or height adjustment capabilities to a vehicle or
implement that
is at least partially supported by a pair of walking beam wheel assemblies are
disposed on opposing sides of a longitudinal plane of the vehicle or implement
and
each feature front and rear wheels that are respectively mounted adjacent
front and
rear ends a single walking beam that is pivotally coupled to a frame of the
vehicle or
implement at a longitudinally intermediate location on the walking beam for
pivoting of
the walking beam about a walking beam pivot axis lying transversely to the
central
longitudinal plane, the method comprising:
replacing at least one walking beam assembly with a respective split
walking beam assembly that is pivotally coupled to the frame for movement
about the
same walking beam pivot axis, and that comprises:
a front beam having front and rear ends spaced apart in a
longitudinal direction in which the central longitudinal plane extends; and
a rear beam having forward and rearward ends spaced apart in
the longitudinal direction, the front end of the front beam being situated
forwardly of
the forward end of the rear beam in the longitudinal direction, the rearward
end of the
rear beam being situated rearwardly of the rear end of the front beam in the
longitudinal direction, the front and rear beams being coupled together
adjacent the
rear and forward ends thereof, and the rear beam being pivotal relative to the
front
beam about a second pivot axis lying transversely of the longitudinal
direction;
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a front wheel rotatably coupled to the front beam adjacent the
front end thereof;
a rear wheel rotatably coupled to the rear beam adjacent the
rearward end thereof; and
a wheel assembly actuator coupled between the front and rear beams of
the split walking beam assembly and operable to pivot the front and rear beams
relative to one another to adjust an angle measured between the front and rear
beams at an underside thereof, whereby, with the front and rear wheels on a
ground
surface, an increase of the angle surface lowers the respective side of the
frame and
respective lateral end of the blade and a decrease of the angle raises the
respective
side of the frame and the respective lateral end of the blade.
The method may include replacing each walking beam assembly with a
respective split walking beam assembly, and further comprising equipping the
vehicle
or implement with a control system operable to control movement of the wheel
assembly actuators.
The control system may be arranged to extend one of the walking beam
actuators while collapsing the other, thereby increasing the angle between the
front
and rear beams of one walking beam assembly while decreasing the angle between
the front and rear beams of the other walking beam assembly so as to raise one
side
of the frame while lowering the other side of the frame.
in such instance, the walking beam actuator may comprise a hydraulic
cylinder with a respective extension port and respective retraction port and
the control
system may comprise a four-way, three-position, spring centered directional
valve,
and the method may comprise coupling a pressure port of the directional valve
to an
output of a hydraulic pump, coupling a return port of the directional valve
with a
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hydraulic fluid reservoir, coupling output ports of the directional valve to
either the
extension ports or the retraction ports of the walking beam actuators, and
coupling the
walking beam actuators together at the other of the extension ports or the
retractions
ports.
5 The directional valve may be a double solenoid directional valve
arranged to use electronic signals to control a position of the valve.
The method may include equipping the vehicle or implement with a tilt
monitoring system arranged to monitor an angular position of the frame about a
roll
axis that extends in the longitudinal direction, and connecting the tilt
monitoring
10 system to the control system to automatically control the walking beam
actuators and
adjust the angular position.
Preferably the second pivot axis of each split walking beam assembly is
coincident with the respective walking beam pivot axis.
Preferably the first and second beams of each split walking beam
assembly both pivot about the second pivot axis.
According to a third aspect of the invention, there is provided a towable
ground working implement comprising:
a tongue having fore and aft ends spaced apart in a longitudinal
direction;
a hitch connector at the fore end of said tongue for coupling of the hitch
connector to a hitch of a towing vehicle;
a scraper blade coupled to the tongue adjacent the rear end thereof and
lying transversely to the longitudinal direction so as to place opposite
lateral ends of
the blade on opposing sides of a central longitudinal plane of the implement
at
outboard positions spaced laterally from said central longitudinal plane;
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a frame situated behind the blade in the longitudinal direction with
opposite sides of the frame disposed on the opposing sides of the longitudinal
plane;
a pair of wheel assemblies, each being attached to the frame adjacent a
respective one of the opposing sides thereof so as to reside on a respective
one of
the opposing sides of the longitudinal plane, at least one of the wheel
assemblies
comprising:
a split walking beam assembly pivotally coupled to the frame for
pivotal movement of the split walking about a first walking beam pivot axis
lying
transversely to the longitudinal direction, the split walking beam assembly
comprising:
a front beam having front and rear ends spaced apart in
the longitudinal direction; and
a rear beam having forward and rearward ends spaced
apart in the longitudinal direction, the front end of the front beam being
situated
forwardly of the forward end of the rear beam in the longitudinal direction,
the
rearward end of the rear beam being situated rearwardly of the rear end of the
front
beam in the longitudinal direction, the front and rear beams being coupled
together
adjacent the rear and forward ends thereof, and the beam being pivotal
relative to the
front beam about a second walking beam pivot axis lying transversely of the
longitudinal direction;
a front wheel rotatably coupled to the front beam adjacent the
front end thereof;
a rear wheel rotatably coupled to the rear beam adjacent the
rearward end thereof; and
a wheel assembly actuator coupled between the front and rear
beams of the split walking beam assembly and operable to pivot the front and
rear
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beams relative to one another to adjust an angle measured between the front
and
rear beams at an underside thereof, whereby, with the front and rear wheels on
a
ground surface, an increase of the angle lowers the respective side of the
frame and
respective lateral end of the blade and a decrease of the angle raises the
respective
side of the frame and the respective lateral end of the blade, thereby
adjusting an
angular tilt position of the blade about a roll axis that extends in the
longitudinal
direction.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1A is an overhead plan view of a land leveler of the present
invention with a blade thereof residing in a level horizontal orientation
parallel to the
ground.
Figure 1B is left side elevational view of the land leveler of Figure 1A.
Figure 1C is a rear elevational view of the land leveler of Figure 1A.
Figure 2A is an overhead plan view of the land leveler of figure 1A with
the blade residing in a tilted orientation in which the end of the blade on a
left side of
the machine is lowered into closer proximity to the ground than the opposing
end of
the blade on the right side of the machine.
Figure 2B is a right side elevational view of the land leveler of Figure 2A.
Figure 2C is a left side elevational view of the land leveler of Figure 2A.
Figure 2D is a rear elevational view of the land leveler of Figure 2A.
Figure 2E is a partial rear perspective view of the land leveler of Figure
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2A from the right side thereof.
Figure 2F is a partial rear perspective view of the land leveler of Figure
2A from the left side thereof.
Figure 3A is a schematic overhead plan view illustrating a hydraulic
control system for controlling the tilt angle of the land leveler of Figure
1A.
Figure 3B is side elevational view of select components of the hydraulic
control system of Figure 3A.
Figure 3C is a schematic perspective view of the hydraulic control
system components of Figure 3B.
Figure 3D is another schematic perspective view of the hydraulic control
system components of Figure 3B.
Figure 4 is a closeup perspective view of a split walking beam tandem
wheel assembly of the land leveler of Figure 1A with wheels thereof omitted
for
illustrative purposes.
Figure 5 is a perspective view of a conventional walking beam tandem
wheel assembly for which the split walking beam tandem wheels assembly of
Figure 4
may be substituted in order to provide a tilt or height adjustment
functionality to a
vehicle or implement previously lacking same.
Figures 6A through 6E are various views of a directional valve and
manifold assembly of the hydraulic control system of Figure 3.
In the drawings like characters of reference indicate corresponding parts
in the different figures.
DETAILED DESCRIPTION
Figures 1A through 2D illustrate a towed land leveler implement 10 of
the present invention. The implement 10 features a pull tongue 12 equipped
with a
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hitch connector 14 at a fore end of the tongue for coupling to the hitch of a
tow vehicle
for pulling of the implement along the ground in forward working direction F.
A box
blade assembly 16 is rigidly attached to the tongue and features a rear blade
18
spanning transversely of the tongue 12 in a position therebeneath adjacent an
aft end
18 thereof that lies opposite to the fore end at which the hitch connector 14
is
mounted.
When the implement is in a level-blade configuration holding the box
blade parallel to the underlying ground, the pull tongue 12 lies in a
vertically oriented
central longitudinal plane of the implement. The rear blade 18 spans from one
side of
the central longitudinal plane to the other in an orientation perpendicular
thereto, thus
placing each lateral end of the rear blade 18 at an outboard location
horizontally
outward from the tongue 12. At each end of the blade 18, a respective planar
end
wall 20 projects forwardly therefrom in a plane parallel to the tongue 12. Box
blade
structures of this type are known in conventional land leveler designs, and
thus are
not described herein in further detail. As is also well known in the art, the
tongue 12
extends forwardly from the box blade assembly 16 to the hitch connector 14 at
the
fore end of the tongue, which therefore defines the forward or leading end of
the
overall machine by which it is pulled by a tractor or other suitable tow
vehicle.
With reference to Figure 1A, a frame assembly 22 resides behind the
blade 18 so as to trail the same during pulling of the implement by a tow
vehicle. The
frame 22 features a main cross-member 24 lying parallel to the blade 18 and
perpendicularly transverse to the tongue 12. The cross-member 24 spans across
the
central longitudinal plane of the machine to place each of the cross-member 24
at an
outboard location spaced laterally outward from the central longitudinal
plane, just like
the blade 18. The length of the cross-member between these two ends is
parallel to,
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but shorter than, the length of the blade 18, whereby each end of the cross-
member
24 lies inboard of the respective end wall 20 of the box blade assembly 16. A
respective longitudinal frame member 26 is attached to the main cross-beam at
each
end thereof, lies perpendicular to the cross-member 24, and extends both
forwardly
5 and rearwardly therefrom. As best seen in the plan views of Figures 1A
and 2A, the
relative positioning of the cross-member 24 and each longitudinal member 26
fixed
thereto may be reinforced by a respective gusset plate 27.
The forward end of each longitudinal frame member 26 features a
pivotal connection 28 to the blade 18, which enables pivoting of the frame
assembly
10 22 relative to the box blade assembly 16 about a pivot axis that lies
perpendicularly
transverse to the tongue and parallel to the blade 18 and the main cross-
member 24.
The pivotal connections 28 of the two longitudinal frame members 26 to the
blade 18
share this same pivot axis, which due to its orientation, may be considered to
be a
pitch axis P of the implement 10. As perhaps best shown in Figures 2E and 2F,
each
15 of these pivotal connections 28 may be formed by pinning of the respective
longitudinal frame member 26 to a respective pair of rearwardly extending lugs
30 on
the rear face of the blade 18. A central lug 32 is fixed on the main cross-
beam 24 and
projects rearwardly therefrom at a midpoint therealong, and one end of a
hydraulic
cylinder actuator 34 is pivotally coupled to the lug 32 by a pivot pin whose
pivot axis is
parallel to the pitch axis P. The opposing end of the hydraulic cylinder
actuator 34 is
likewise pivotally pinned to a pair of mounting brackets 36 on the rear of the
blade 18,
as perhaps best shown in Figure 2E. Extension and retraction of the actuator
34 thus
pivots box blade assembly 16 and attached tongue 12 relative to the frame 12
about
the pitch axis P, for example in order to lower the blade 18 down into
engagement
with the ground to perform a ground-working, earth-moving operation, or to
raise the
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blade out of contact with the ground for transport of the machine.
Each longitudinal frame member 26 defines a respective side of the
frame 22 on a respective one of the two opposing sides of the central
longitudinal
plane of the machine. Near the rearward end of each longitudinal frame member
26
that lies distally of the cross-member 24, a pivot pin or stub shaft 38 passes
transversely through the longitudinal frame member 26 in a direction parallel
to the
pitch axis P, and projects outwardly from the longitudinal frame member 26
through
front and rear beams 40, 42 of a respective split walking beam assembly 44 in
order
to pivotally connect same to the frame 22. Like a conventional walking beam,
this
split walking beam assembly 44 rotatably supports a pair of wheel axles 46, 48
near
its opposing ends, so that two wheels 50, 52 mounted on these axles are
rotatably
carried on the walking beam in tandem positions relative to one another. The
wheel
axles 46, 48 lie parallel to the pivot pin or stub shaft 38. However, in the
present
invention, instead of the front wheel 50 and rear wheel 52 being rotatably
supported
on the same rigid beam, the front wheel 50 is rotatably carried on the front
beam 40
that spans a front half of the overall walking beam assembly 44, and the rear
wheel
52 is rotatably carried on a rear beam 42 that spans a rear half of the
overall walking
beam assembly 44. In the fore-aft longitudinal direction of the implement, the
front
end of the front beam is spaced forwardly of the forward end of the rear beam
in the
long, the rearward end of the rear beam is spaced rearwardly of the rear end
of the
front beam, and the front and rear beam overlap one another at the forward end
of the
rear beam and rear end of the front beam.
In each split walking beam assembly 44, the front and rear beams 40,
42 lie side-by-side with one another a short distance to the outside of the
respective
longitudinal frame member 26, and each feature a respective upright lug 58, 60
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projecting upward from the topside of the beam 40, 42. A respective hydraulic
cylinder actuator 62 of each walking beam assembly 44 has its opposing ends
pivotally coupled to the front and rear top lugs 58, 60 by pivot pins whose
axes lie
parallel to the pitch axis P of the machine.
The stub shaft or pivot pin 38 passing through the respective
longitudinal frame member 26 also passes through both the front and rear beams
40,
42 of the respective walking beam assembly 44 at an area where the two beams
40,
42 overlap in the longitudinal direction of the machine. The stub shaft or
pivot pin 38
thus defines a main walking beam pivot axis W on which the collective walking
beam
assembly is pivotal relative to the frame 22, and also defines a coincident
second
walking beam pivot axis about which the front and rear beams 40, 42 are
pivotable
relative to one another by extension and retraction of the walking beam
actuator 62.
This direct coupling together of the front and rear wheel carrying beams of
the walking
beam assembly by the same shaft or pin that couples the walking beam assembly
to
the frame 22 reduces the number of parts by avoiding an intermediary between
the
front and rear beams on which the front and rear wheels are mounted and
sharing the
same pivot point for both the relative pivoting between the front and rear
beams and
the pivoting of the overall walking beam assembly relative to the frame.
When the length of the walking beam actuator 62 is maintained, an
angle a measured between the front and rear beams 40, 42 about the axis of the
stub
shaft or pivot pin 38 walking beam assembly 44 is likewise maintained, and the
walking beam assembly acts as a conventional walking beam in which the
positions of
the two wheels 50, 52 are stationary relative to one another. On the other
hand, each
side of the frame 22 can be raised and lowered relative to the ground G by
varying the
angle a between the front and rear beams 40, 42 through extension and
retraction of
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the respective walking beam actuator 62. Particularly, if angle a is measured
between
the undersides of the two beams 40, 42, then extending the length of the
actuator 62
pushes apart the front and rear lugs 58, 60 at the topsides of the beams 40,
42, thus
forcing the undersides of the two beams toward one another and reducing the
angle
a. This pushes each of the two wheels 50, 52 downwardly against the ground G
on
an arcuate path about the stub shaft or pivot pin 38, thereby lifting the
respective side
of the frame 22 upwardly away from the ground G. Conversely, retracting the
length
of the actuator 62 draws the front and rear lugs 58, 60 toward one another,
thus
drawing the undersides of the two beams away from one another and increasing
the
angle a in order to lower the respective side of the frame 22 downwardly
toward the
ground G. By using the actuator 62 of each walking beam assembly to vary the
positions of the two respective wheels 50, 52 relative to one another about
the
respective stub shaft or pivot pin 38, the height of each side of the frame
can thus be
varied, and the heights at the opposing sides of the frame can be set to
different
values in order to tilt the frame 22 and the connected box blade assembly 16
about a
longitudinal roll axis R that lies perpendicular to the pivot axes W of the
walking beam
assemblies 44.
In the illustrated embodiment, the front beam 40 of each split walking
beam assembly 44 resides adjacent the outer side of the respective
longitudinal frame
member 26, and the rear beam 42 resides opposite the longitudinal frame member
26
to the outside of the front beam 40. The rear wheel 52 is mounted to the
inside of the
rear beam 42, thus riding on the ground in a position trailing behind the
longitudinal
frame member 26 in the shadow of same. The front wheel 50 is mounted to the
outside of the front beam 40, i.e. on the side thereof opposite the frame 22.
The front
wheel 50 resides nearer to the plane of the respective end wall 20 of the box
blade
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assembly 16 than the rear wheel, but still a short distance inboard from this
plane. By
placing the two wheels of each walking beam assembly on opposite sides
thereof, the
wheels are slightly spaced apart from one another in the tranverse direction
of the
machine. This way, a rock, bump or other surface disruption on the ground that
is
met by one wheel will not necessarily be hit by the other.
To demonstrate the functionality of the variable-angle split walking
beams, comparison is made between Figures 1 and 2. Figure 1C shows the blade
in
a level orientation parallel to the ground G, i.e. in a horizontal orientation
when all four
wheels are resting on a planar, horizontal ground surface. As shown in Figure
1B, the
value of angle a is the same for the two walking beam assemblies when the
blade is
level, specifically at a value of 180-degrees in the case of the illustrated
scenario. In
comparison, Figure 2D shows the box blade and frame in a tilted orientation
with the
left side thereof lowered into a position closer to the ground G than the
right side.
From the perspective views of this tilted blade orientation in Figures 2E and
2F, it can
be seen that this orientation is achieved by using the actuators 62 of the
walking
beam assemblies to set the angle a of the left walking beam assembly to a
greater
value than that of the right walking beam assembly. From the initially level
orientation
of Figure 1, this tilted orientation was achieved by collapsing the actuator
62 of the left
walking beam assembly in order to increase the angle a thereof, and extending
the
actuator of the right walking beam assembly in order to decrease the angle a
thereof.
The illustrated embodiment is equipped with a control system 70 for
monitoring and automatically controlling the tilt angle of the frame and blade
about the
roll axis R. This system 70 is schematically illustrated in Figure 3A. A four-
way,
three-position, double-solenoid, spring-centered directional valve 72 is used
to control
operation of the hydraulic cylinder actuators 62 of both walking beam
assemblies so
CA 02876456 2015-01-07
as to automatically extend one of these actuators while collapsing the other
during
any adjustment of the blade tilt angle. Accordingly, tilting motion is
achieved by
simultaneous inverse operation of the two actuators 62 so to raise one side of
the box
blade 16 and frame 22 while lowering the other side thereof. A hydraulic
manifold
5 block
74 is cooperatively attached to the valve 72 for connection of the necessary
hydraulic hoses to the valve. In the illustrated embodiment of the machine,
the
valve/manifold assembly 72, 74 is mounted atop the cross-beam 24 of the frame
at a
slightly off-centre position beside the mounting lug 32 of the pitch-angle
blade 34
actuator, although other mounting positions can alternatively be employed.
10 Using
the manifold block 74, a hydraulic supply hose 76 is coupled
between a pressure inlet port of the valve 72 and a hydraulic pump 78 in order
to
provide fluid communication between same. The pump 78 may be part of the
implement 10 or part of the tow vehicle. For example, conventional
agricultural
tractors have an onboard hydraulic system for powering hydraulically driven
15
implements, in which case the existing pump of the tractor can be used to
power the
control system of the implement 10 by running the supply hose 76 along the
tongue
12 from the directional control valve to the fore end of the tongee 12, where
the
supply hose has a suitable fitting for coupling to a power hose of the tractor
that is fed
by the tractor's hydraulic pump. Via the manifold block 74, a hydraulic return
hose 80
20 is
coupled between a tank return port of the valve 72 and a hydraulic fluid
reservoir 82
in order to provide fluid communication between same. The valve 72 has two
output
ports, each connected to a respective one of the walking beam actuators 62,
via the
manifold block 74, by a respective hydraulic output hose. More specifically,
via the
manifold block 74, a first hydraulic output hose 84 is coupled between one
output port
of the valve 72 and the extension port 86 of one of the walking beam actuators
62 (i.e.
CA 02876456 2015-01-07
21
the port of the actuator on the side of its piston that drives extension of
the actuator's
piston rod when pressurized). A second hydraulic output hose 88 is likewise
coupled
between one output port of the valve 72 and the extension port 90 of the other
one of
the walking beam actuators 62. Finally, a hydraulic connection hose 92
completes
the final hydraulic connection among the valve and walking beam actuators by
connecting the retractions ports 93 of the two actuators 62 together (i.e. the
port on
the side of the piston that drives retraction of the piston rod further back
into the
cylinder when pressurized).
Through these connections, the two walking beam actuators 62 are
connected together in series such that extension of one actuator automatically
collapses or retracts the other. The valve 72 is a normally closed valve, in
which the
spool of the valve 72 is spring biased into a central closed position,
blocking off the
pressure port from both of the output ports. A respective solenoid 72a is
attached to
each end of the spool so that activation of either solenoid pulls the spool
into a
respective one of two open positions, each of which communicates the pressure
port
with a respective one of the two output ports and communicates the return port
with
the other one of the two output ports. In each open position, one of the
walking beam
actuators 62 is extended by pressurizing the extension side of the cylinder,
which
drives the internal piston toward the retraction port of that cylinder,
thereby exhausting
hydraulic fluid from the retraction side of that cylinder into the retraction
side of the
other hydraulic cylinder actuator, thereby pressurizing same. The second
cylinder is
thus retracted, with the hydraulic fluid on the extension side thereof being
conveyed
back to the manifold/valve for exhaust back to the reservoir tank 82.
Accordingly, the
two actuators 62 act inversely to one another, with one actuator being
automatically
retracted by the extension of the other.
CA 02876456 2015-01-07
22
An electronic tilt monitoring system 94 features a tilt sensor mounted
somewhere on the box blade assembly 16 or frame 22 and operable to monitor the
angular position of same about the roll axis R. Output signals from the tilt
sensor are
employed as an input for automatic control the directional valve 72 based at
partially
on these signals. The tilt monitoring system may be preconfigured or
programmed
with a target angular position that is to be maintained by this automated
control, for
example a tilt angle of 0-degrees, representing a level blade orientation. In
preferred
embodiments, the user can set or select a target angle, preferably on the fly
from the
operator cabin of the tow vehicle. Deviation from the target angular position
in either
direction activates the respective one of the solenoids 72a that extends the
actuator
62 on the side of the frame that needs to be raised relative to the other in
order to
regain the target tilt angle of the blade, and holds this open condition of
the valve until
the target tilt angle is re-established, at which point the solenoid is
deactivated, at
which the spring-centered spool of the valve is returned to the closed
position.
Directional control valves of the described type are well-known and
commercially available. As an example, a model D1VVV001CNCK4 directional
control
valve from Parker Hannifin Corporation of Elyria, Ohio may be employed. The
illustrated embodiment is based on a prototype featuring a model ADO3P012S
parallel
circuit valve manifold from Daman Products Company Inc. of Mishawaka, Indiana,
which features two tank return ports T, two pressure ports P, a first output
port A, and
second output port B, but has been repurposed for the control system of the
present
invention from its original configuration by closing the T port on one face
and the P
port on the opposing face with threaded plugs 73, using the A port as the
tank/return
port for the reservoir tank 82, using the B port as the pressure port from the
pump 78,
using the remaining T port on one face of the manifold block as the output
port to one
CA 02876456 2015-01-07
23
actuator 62 and using the remaining P port on the opposing face of the
manifold block
as the output port to the other actuator. Use of a specially produced
manifold, or
commercially available manifold of appropriate port and passage configuration,
may
of course be used in place of the repurposed Daman manifold.
U.S. Patent Application Publication 2012/0239258, the entirety of which
is incorporated herein by reference, discloses and example of a tilt
monitoring system
that employs a blade tilt angle sensor in combination with a gyroscope and a
blade tip
angle sensor to provide optimal input to a hydraulic blade-tilt control
system. The tilt
measurement system of the incorporated reference may be employed as the blade
tilt
monitoring system 94 in the present invention, with the output therefrom
controlling
operation of the solenoids 72a of the directional control valve 72 so as to
operate the
walking beam actuators 62 of the present invention to lift and lower the frame
and
blade, instead of controlling the blade-tilt actuators 112, 114 of the prior
art reference
that act directly between a grader blade and primary frame of a grader
vehicle. Other
automated tilt monitoring systems and methods known in the art may
alternatively be
used as input to the hydraulic control system 70 of the present invention. For
example, the tilt monitoring system 94 may use a single tilt sensor alone
(i.e. without
the accompanying gyroscope and tip-angle sensor from the incorporated
reference)
as the sole measurement source, although this may be prone to slower response
time
in control of the blade and reduced accuracy in the measurements, as outlined
in the
incorporated reference.
Although some embodiments of the present invention employ the above
described automated control of the blade angle, other embodiments may be
manually
controlled by the operator of the tow vehicle, for example by conveying
electrical
control signals from a manual lever or other control mechanism in the operator
cabin
CA 02876456 2015-01-07
24
of the tow vehicle to the directional control valve, for example via suitable
wiring run
along the pull tongue 12 of the implement, or by way of a wireless
communication link.
The solenoid-operated valve 72, and the monitoring system 94, may be powered
from
the electrical system of the tow vehicle, thus avoiding the need for a
dedicated power
supply onboard the implement itself, although such an option may be employed
in
other embodiments.
While the illustrated embodiment features two split walking beam
assemblies 44, another embodiment may feature replacement of one of the split
walking beam assemblies 44 with a conventional fixed-beam walking assembly,
whereby the tilt angle of the blade is set by adjusting the one split walking
beam
assembly to set the height at one side of the frame, without changing the
height of the
other side of the frame. While the illustrated embodiment features a hydraulic
control
system that automatically operates the two actuators in inverse of one
another, other
embodiments are also contemplated. For example, split walking beam assemblies
on
opposing sides of a vehicle or implement (whether a land leveler, or other
machine)
may be beneficial even with other control configurations, for example in a
control
configuration where the two walking beam actuators are again operated
simultaneously, but in the same direction, so as to control and overall height
of the
vehicle, or in a control configuration in which the two walking beam actuators
are
operable independently of one another, for example to set a desired height at
one
side of the frame, and a desired tilt angle of the frame. Split walking beam
assemblies can thus be used for a variety of different vehicle or implement
types,
including self-conveying vehicles or implements (as opposed to the towed
implement
of the illustrated embodiment), earth-working implements other than levelers
(for
example implements of varying types of ground engagement arrangements, such as
CA 02876456 2015-01-07
gangs, groups or arrays of ground working members with discrete ground
engagement points instead of a continuous blade running fully from one end of
the
ground working arrangement to the other), and vehicles or implements that lack
an
earth-working function, but nonetheless could benefit from height and/or tilt
control in
5 an adjustable angle split walking beam assembly.
With reference to Figures 4 and 5, a conventional rigid-beam walking
axle assembly 100 of the type shown in Figure 5 can be substituted for a split
walking
beam assembly 44 of the present invention simply by replacing the existing
stub shaft
or pivot pin 102 of the existing walking beam 100 with a longer stub shaft or
pivot pin
10 38 of sufficient length to pass through both beams of the new split walking
beam
assembly 44, which is thus mounted on this new stub shaft or pivot pin 38.
Walking
beams on opposing sides of the frame of the previously-conventional vehicle
can thus
be replaced in this manner. The hydraulic actuators 62 of the split walking
beams
then be connected to an existing hydraulic system of the vehicle or implement,
if so
15 equipped, or a hydraulic system can be added to the vehicle or implement
if it
previously lacked a suitable hydraulic power system for the split walking
beams.
Examples of vehicles in which an adjustable angle split walking beam axle may
be
useful include rock trucks, semis, mining equipment, military equipment such
as troop
transporters, or possibly even for idler wheels of track-equipped vehicles.
20 Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
within the scope of the claims without departure from such scope, it is
intended that all
matter contained in the accompanying specification shall be interpreted as
illustrative
only and not in a limiting sense.
