Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02292347 1999-12-17
Title: FOLDING BLADE
Field of the Invention
This invention relates to plowing equipment. More
particularly, it relates to a support system for a mid-
chassis, underbody plow or scrapper system that controls the
deployment of a blade and its storage beneath the vehicle
between deployment. The invention is suited especially for
installation on the underbody of trucks for use as snow plows.
Backaround to the Invention
Mid-chassis or underbody plows and scrappers are
well known vis. U.S. Patent Nos. 4,031,966; 4,337,832. Such
plows have been designed to fold upwardly for storage, c.f.
U.S. Patent No. 4,031,966 depicting rearward folding.
In designing an underbody plow or scrapper with a
folding blade it is desirable to provide adjustability to
raise or lower the blade, to tilt the blade, raising its outer
ends up and down about a horizontal axis that is generally
pointed outwardly from the blade surface. Blades are often
required to be angled to the left and right about a vertical
axis. It is also desirable when the plow blade is light, to
provide a supplementary force-control mechanism that will
apply a downward force to the plow blade to maintain it in
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contact with the surface being plowed with the appropriate
level of pressure. It would be highly desirable to combine
these features with an under body plow having a storage
feature that would permit it to be raised above the road
surface when not deployed.
These features of control should ideally be
achievable, in whole or in part, at minimal cost and with a
minimal addition of weight to the vehicle.
It is therefore an object of the invention to
provide an underbody blade support system that has various
combinations of the above features combined with simplicity
and low cost.
The invention in its general form will first be
described, and then its implementation in terms of specific
embodiments will be detailed with reference to the drawings
following hereafter. These embodiments are intended to
demonstrate the principle of the invention, and the manner of
its implementation. The invention in its broadest and more
specific forms will then be further described, and defined, in
each of the individual claims which conclude this
Specification.
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Summary of the Invention
The invention employs an underbody plow blade or
scrapper with a mold board and two outer ends, (hereafter
referred to generally as a scrapper blade) which is mounted to
extend generally transversely beneath the chassis of a
vehicle. This scrapper blade is positioned between the
forward and rearward sets of wheels on the vehicle and may be
angled to be oriented to the left or right while still
extending generally transversely beneath the vehicle.
A feature of the invention is that the blade may be
folded, preferably forwardly, to raise it above the road
surface in a stored position. In its folded orientation, the
mold board of the plow is upwardly directed. Preferably,
rotation of the mold board from its deployed position is
effected about a hinge line that is rearwardly of and
intermediate the top and bottom edges of the mold board. The
top edge may, in being folded, retire from a first deployed
stop means to a second folded stop means against which the top
edge may bear.
Preferably, the blade-folding system of the
invention is carried by an elevating support to cause the
folded blade to retire upwardly. Thus, in a preferred
arrangement, the blade may be carried at the end of a pivot
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arm assembly in the form of two trailing arms that are mounted
to the chassis so as to extend downwardly from a forwardly-
mounted hinge mount. The upper edge of the mold board may
nest in a recess formed in the pivot arms. The pivot arm
assembly hinge mount allows rotation of the pivot arm assembly
about an axis that is also generally transverse to the
direction of motion of the vehicle. Other means of supporting
and elevating the blade are, however, permissible, in order to
provide this two-stage storage effect.
The scrapper blade is preferably tiltable in the
sense that one of its two outer ends may be elevated
vertically with respect to the other end. This may be
effected in one preferred manner by providing a rotatable
coupling between the vehicle chassis, e.g. within the pivot
arm assembly, and the scrapper blade that allows the scrapper
blade to rotate about a generally horizontal axis extending
forwardly and rearwardly beneath the vehicle. Other means of
providing for such freedom of motion may also be employed,
including independently hinged pivot arms.
Preferably the scrapper blade with its scrapping
edge is positioned against a road surface by two pressure
actuators respectively located between the blade and the
vehicle chassis at spaced locations on either side of the
centerline of the vehicle. These pressure actuators may be in
the form of pneumatic bladders to apply a resilient downward
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pressure on the scrapper blade through the elevating support.
In the case of the use of a pivot arm assembly, the pressure
actuators may be positioned between the chassis and the pivot
arms.
5 As an optional feature, by independent control of
the pressure actuators, differing vertical forces may be
applied to the respective outer ends of the scrapper blade.
Consequently a greater amount of contact pressure may be
maintained between the scrapper blade and the surface being
scrapped at one outer end of the blade than at the other outer
end. This greatly facilitates the removal of snow, ice or
other debris from a road surface when the level of material to
be removed is higher on one side of the vehicle than on the
other side of the vehicle.
The preferred type of pressure activator is a
pneumatic bladder of the type generally employed in air
springs. Their role is to press the blade edge resiliently
against the road surface, lifting-off ice, snow and debris
from that surface. Such devices are not only relatively
inexpensive, but also provide a "spring" resilience that
allows the scrapper to move vertically to accommodate vertical
variation in the surface being scrapped.
To complement the folding action by which the
scrapper blade is raised for storage above the road surface,
the elevating support, e.g. the pivot arm assembly, may be
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provided with a blade folding actuator coupled between the
pivot arm assembly and the vehicle chassis to serve as well as
a lifting actuator. Action as a lifting actuator may be
achieved in conjunction with the folding of the blade by
providing a lifting link, such as a chain, that extends
between a folding portion of the blade and the vehicle
chassis.
The foregoing summarizes the principal features of
the invention and some of its optional aspects. The invention
may be further understood by the description of the preferred
embodiments, in conjunction with the drawings, which now
follow.
Summary of the Fiaures
Figure 1 is a side view of a prior art vehicle
carrying a mid-chassis, underbody plow blade carried by a
pivot arm assembly that serves as one aspect of a preferred
variant of the invention when combined with a folding plow
blade;
Figure 2 is a perspective view of a cut-away portion
of the vehicle of Figure 1 taken from the left rear quarter
with the pneumatic actuators omitted for clarity;
Figure 3 is the view of Figure 2 with pneumatic
actuators depicted in position;
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Figure 4 is a rear-end view of the vehicle of Figure
1 with the pivot arm assembly lowered;
Figure 4a is a rearward view of the vehicle of
Figure 1 with the pivot arm assembly raised;
Figure 4b shows a rearward face view of the tilting
plate assembly;
Figure 5 depicts the vehicle of Figure 2 with the
air distribution and control system in place;
Figure 6 is a plan view of the folding blade
configuration of the invention;
Figures 7a and 7b are side views of the blade of
Figure 6 respectively deployed and folded for storage;
Figures 8a and 8b are side views along the blade
respectively when deployed and when folded;
Figure 9 is a detailed view of Figure 8a showing the
stored view of the blade of Figure 8b in ghost outline;
Figure 10 is a plan view of a folding blade
configuration of the invention having separately hinged pivot
arms to provide the pivot arm assembly.
Description of the Preferred Embodiment
In Figure 1 a vehicle 1 having a chassis 2, forward
wheels 3 and rearward wheels 4 carries between these sets of
wheels 3,4 a scrapper blade or plow blade 5. While reference
hereafter will be made to a "blade" 5 this language is
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intended to encompass any form of scrapper blade, including
rake and chisel-like constructions.
Figure 1 is prior art. However, Figure 1 will be
described in detail because it provides a synergistic
environment for the folding blade feature of the invention.
The blade 5 is carried by a pivot arm assembly 6
having two pivot arms 6a, 6b that trail below the chassis 2
from pivot arm hinges 7 coupled to the chassis 2 at the
forward end of each pivot arm 6a,6b. The hinges pivot arm 7
permit rotation of the pivot arms 6a,6b about an axis that is
transverse to the direction of the vehicle 1. The pivot arms
6a,6b may be mounted to rotate independently (not shown) to
permit the blade 5 to tilt. An alternate, preferred tilting
arrangement is detailed further, below.
Positioned between the chassis 2 and blade 5 are two
pneumatic bellows 9a, 9b respectively mounted on opposite sides
of the centerline 10 of the vehicle 1. Based on pneumatic
springs, these bellows 9a,9b act as controllable pressure
actuators which are able, in a preferred arrangement, to apply
independently differing pressures to the outer ends lla,llb of
the blade 5.
A preferred structure for allowing the blades to
tilt, i.e. to effect vertical displacement of the outer ends
lla, llb of the blade 5, is shown in Figures 2-5. For
simplicity of depiction, the blade folding feature of the
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invention is not shown in Figures 2-5. Tilting is effected by
the presence of a rotary coupling 12 incorporated into a pair
of transverse tilting plates 13a,13b. A first one of these
plates 13a extends between the pivot arms 6a,6b; the second of
these plates 13b extends between two blade support arms 14a,
14b that connect to the blade 5. A central pin 15 coupled to
the two tilting plates 13a,13b permits rotation of the blade
support arms 14a, 14b and blade 5 about a horizontal axis that
is generally aligned with the direction of travel 10 of the
vehicle 1.
The plates 13a, 13b preferably are positioned
closely together so that their outer ends may brush together
to absorb dislocating forces that tend to swivel the blade 5
to the left or right. As well, welded pins or bolts 45 may
extend from the ends of one plate 13a to carry containment
plates 46 that contain or "trap" the outer ends of the second
plate 13b (or in the reverse arrangement extending from the
second plate 13b to contain the first plate 13a). This is to
absorb tensional forces while permitting rotation between the
plates 13a,13b. Specific bearing surfaces may be provided
with respect to each of the plates 13a,13b to absorb the
brushing contact action.
In Figure 2 the alternate position of the tilted
blade 5 is shown in ghost outline 5a with one end llb raised
and the other end lla lowered.
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In Figure 3 the pneumatic bellows 9a, 9b omitted from
Figure 2 for clarity are shown positioned to apply force
between the chassis 2 and the blade 5 through the respective
blade support arms 14a, 14b. These pressure actuators 9a,9b
5 are spaced apart and positioned to apply similar or differing
pressures at the outer ends of the blade 5 in pressing the
blade downward onto a road surface 36.
The pivot arm assembly 6 may be raised by chains 16
descending from a frame 17 that includes a transverse bar 18
10 that overlies a further air spring lifting bellows 19
positioned on the chassis 2. The pivot arms 6a, 6b according
to this lifting arrangement are coupled to the chains 16 at
locations between their ends to provide the action of a third
class lever.
To raise the blade 5, the pressure in the pressure
actuator bellows 9a,9b is released (through valves 24) and
that in the lifting bellows 19 is increased. The force of the
lifting bellows 19 is transmitted through the frame 17 and
chains 16 to the pivot arm assembly 6 raising the blade 5
upwardly off of the surface being scrapped. This operation
may be seen in Figures 4 and 4a wherein the pivot arm assembly
6 is respectively lowered and raised. An alternate lifting
arrangement may be employed with the folding-blade
configuration, described further herein.
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The control system for the blade support is depicted
in Figure 5. A source of pressurized air 21, depicted as an
air tank, provides air to a pressure distribution box 22.
Pressurized air is directed from this box 22 to the lifting
bellows 19 and pressure actuator bellows 9a,9b, through air
lines 23 in response to manually set input signals, preferably
originating remotely from within the vehicle cab. Exhaust
valves 24, responding in cooperation with the operation of the
pressure distribution box 22, exhaust or vent air from bellows
9a,9b,19 when they are to be depressurized, e.g. venting
lifting bellows 19 when pressure actuators 9a,9b are
pressurized. Manometers 25 display the pressure conditions
within the system.
Through the pressure distribution box 22, controlled
levels of pressure may preferably be developed independently
in each of the bellows 9a,9b controlling the scrapping effect
of the blade 5 on the road surface. A different pressure need
not necessarily be applied through the bellows 9a,9b; but such
option is available.
The folding-blade feature of the invention is shown
in plan view in Figure 6. To assist in perceiving the
positioning of the plow components, the wheels 3, 4 are
depicted at disembodied locations in Figures 6, 7a and 7b.
In Figures 6, 7a and 7b the tilting plates 13a, 13b
have been shifted forwardly under the vehicle, to a location
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proximate to the pivot arm hinges 7. In this arrangement, the
pivot arms 6a,6b are greatly shortened and the blade support
arms 14a,14b are greatly lengthened. The freedom of action
provided to permit the blade 5 to tilt is, however, the same
in principle as described previously. For the further
discussion following herein, the blade support arms 14a,14b
will be addressed as forming part of the pivot arm assembly 6.
In Figure 6 the blade 5 is fixed transversely to the
chassis 2 at an angle, e.g. 28 degrees, out of alignment with
the vehicle. The blade 5 is carried by the two support arms
14a,14b and respective air bladders 49a,49b are positioned to
develop a downward thrust upon such arms 14a,14b.
The blade 5 has its own blade hinge axis 30 and is
positioned by a cylinderical actuator 31 mounted on a
transverse bar portion 32 of the pivot arm assembly 6. A
linearly actuated shaft 33 extends from the actuator 31 to
join with the blade 31 at a blade-actuator hinge 34. The
blade hinge axis 30 is behind the blade 5, positioned
intermediate of the upper edge 32 and the scrapping edge 37 of
the blade 5.
The dual folding action of the blade 5 is shown in
Figures 7a and 7b which respectively depict blade 5 as
deployed and folded upwardly for storage. It will be noticed
that, as a preferred feature, the support arms 14a,14b are
also swung upwardly from their deployed position, in Figure
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7a, to their storage position, in Figure 7b, when the blade 5
is folded upwardly with mold board 5a of the blade directed
upwardly. The upward swing raises the arcuate portion 39 of
the arms 14a, 14b closing-up the difference 50,50a.
In Figures 8a and 8b, details of the blade-folding
action are shown in side view, looking endwise along the blade
5. In Figure 8a the blade 5 is deployed with its scraping
edge 35 positioned on a road surface 36 and its upper edge 37
bearing against a blade-deployed stop surface 38 positioned on
arcuate portion 39 of the support arms 14a, 15b of the pivot
arm assembly 6. The shaft 33 of the actuator 31 is fully
extended, having carried the upper edge 37 of the blade 5 to
the stop surface 38. Thus the stop surface 38 absorbs the
obstructions encountered by the blade 5 on the road surface
36, rather than the actuator 31.
In Figure 8b the blade 5 is shown as folded, the
upper edge 37 having passed rearwardly beneath arcuate
portions 39 of the support arms 14a,14b upon retraction of the
shaft 33 (not visible in Figure 8b) to rest against folded-
blade stop surface 38a. Rotating about blade hinge axis 30,
the lower, scraping edge 35 is elevated above the road surface
36 to present the mold board 5a of the blade upwardly once the
upper edge 37 reaches the folded-blade stop surface 38a.
To achieve a double-action lifting effect with a
maximum economy of components, a linkage in the form of a
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chain 40 extending between the blade 5 and chassis 2 is
tightened by the retraction of shaft 33 and the forward
rotational advance of the lower half of the blade to which it
is connected. The action draws the support arms 14a,14b
upwardly towards the chassis 2. The corner 41 formed on the
transverse bar portion 32 of the pivot arm assembly 6 may be
strengthened and shaped to permit the chain 40 to slide around
this corner 41 during this lifting action. A stopping arm 50
connected to the transverse bar 32 rises until it abuts a
chassis rest 51, limiting further upward travel of the blade
5 pivot arm assembly 6.
As shaft 33 is not in an intersecting alignment with
hinge axis 30, the linear actuator 31 is mounted to the
transverse bar portion 32 by a swivelling support means that
rotates about actuator axis 42 (indicated as to its location
in Figures 8a, 8b). Thus the actuator 31 has differing
orientations in Figures 8a and 8b. The difference in these
orientations are shown in Figure 9 wherein a ghost outline 31a
shows the actuator 31 when the blade 5 is in its stored
position.
Figures 1 through 5 depict an environment in which
the folding blade 5 of Figures 6 through 9 may be installed.
In Figure 10 the pivot arm assembly 6 is shown as being
attached to the chassis 2 by independent hinge joints 53.
These joints 53, optionally of the Torrington type, allow the
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pivot arms 14a, 14b to rotate independently. This dispenses
with the need for tilting plates 13a, 13b.
As shown in Figure 10, a side of the stopping arm 50
may bear against a portion of the chassis 2 to limit sideways
5 displacement of the blade 5 and pivot arms 14a, 14b.
The combined effect of both folding the blade 5 to
direct its mold board 5a upwardly and swinging the support
arms 14a,14b upwardly allows the blade 5 to be stored with
maximum elevation under the chassis 2. This is highly
10 desirable as it allows the vehicle to travel at high speeds
over uneven road surfaces 36 with reduced risk that the stored
blade 5 will contact a protruding portion of the road surface
36 or strike an object lying on the road.
The use of air-activated pressure actuators 9a,9b
15 renders the blade support of the invention light in weight and
less costly than hydraulic systems. The light weight of the
blade 5 and pivot arm assembly 6 is supplemented by pressure
applied through the bellows 9a,9b, 49a,49b which respond
resiliently to variations in the height of the road surface
36. The rotary coupling 12 of the tilting plates 13a,13b in
the pivot arm assembly 6, or the use of flexible Torrington-
type joints 53, allows the scrapper blade 5 to adjust to the
contour of the road surface 36 in the preferred variants of
the invention. The angled orientation of the blade 5 allows
debris to be transferred to the left or right side of the
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vehicles. Individually and collectively an improved means is
provided for clearing a road surface.
Conclusion
The foregoing has constituted a description of
specific embodiments showing how the invention may be applied
and put into use. These embodiments are only exemplary. The
invention in its broadest, and more specific aspects, is
further described and defined in the claims which now follow.
These claims, and the language used therein, are to
be understood in terms of the variants of the invention which
have been described. They are not to be restricted to such
variants, but are to be read as covering the full scope of
the invention as is implicit within the invention and the
disclosure that has been provided herein.
