Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
V-BLADE SNOWPLOW HAVING DUAL TRIP MECHANISM
BACKGROUND
[00011
Field of the Disclosure
[00021 This disclosure relates generally to trip mechanisms for snowplows and,
more
specifically, to V-blade snowplows having a dual trip mechanism.
Related Technology
[00031 Generally speaking, snowplow blades come in two different types, a
straight blade
and an adjustable or V-blade. The straight blade generally extends across the
front of a
vehicle, such as a truck. Some straight blades may be angularly adjustable
relative to the
longitudinal axis of the vehicle. For example, some straight blades may have
the capability
to angle the straight blade relative to the longitudinal axis of the vehicle.
While straight
blades generally push snow well, they are not very adaptable to plowing
confined areas or
odd-shaped areas,
[0004] V-blade snowplows, on the other hand, are more adaptable. V-blades are
formed
by two wings or blades (a driver's side blade or left wing, and a passenger's
side blade or
right wing) that meet at a center hinge. Each blade may be independently
adjustable relative
to the longitudinal axis of the vehicle. As a result, the V-blade may have
multiple useful
configurations. For example, the V-blade may take on a V-shape with each blade
extending
at an angle from the center hinge, rearwardly toward the vehicle. The V-blade
may also take
on an inverted V-shape or scoop configuration, where each blade extends at an
angle forward
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from the center hinge, away from the vehicle. Finally, the V-blade may mimic a
straight
blade by having one blade extend forward from the center hinge and another
blade extending
rearward from the center hinge. As a result of the different configurations,
the V-blade is
known to be generally more adaptable to unique plow areas, especially confined
plow areas.
[0005] In practice, areas to be snow plowed are rarely flat and level. To the
contrary, most
plowing areas have uneven terrain and even obstacles extending upward from the
plowing
surface, such as curbs, manhole covers, reflectors, ADA-mandated tactile
warning tiles, and
other objects. Snowplow blades must have the capability to adjust to the
uneven terrain and
to overcome the obstacles without breaking the obstacle or the blade. When a
snowplow
blade meets an obstacle, it "trips" in one or more directions to allow the
blade, or a portion of
the blade, to adjust so that the snowplow blade may pass over the obstacle.
Generally, there
are two types of trip mechanisms: An edge trip mechanism and a full blade trip
mechanism.
[0006] In edge trip mechanisms, a cutting edge strip is hingedly attached
along the bottom
edge of a main blade or moldboard. The cutting edge strip is biased forward,
into general
alignment with the bottom of the moldboard, by one or more springs. When an
obstacle is
encountered, and enough force is generated to overcome the spring bias, the
cutting edge strip
pivots rearward, allowing the main blade to pass over the obstacle. Once the
obstacle has
been passed over, the spring-biased cutting edge strip returns, due to the
spring bias, to its
normal untripped position. The cutting edge strip is typically made of a
sacrificial material,
such that it is slowly worn away during the plowing process through friction
with the plowing
surface. As the sacrificial material wears down, the maximum obstacle
clearance height is
slowly reduced because the maximum height of the cutting edge strip is
reduced. Eventually,
the user must replace the cutting edges. One drawback of the edge trip
mechanisms is that
they are obstacle height-limited. In other words, if an obstacle is
encountered that is higher
than the thin cutting edge strip, the obstacle will contact the main blade
(even if the thin
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cutting edge strip rotates out of the way). Such an encounter can cause damage
to the main
blade, the blade mounting hardware, and/or the vehicle itself.
[0007] In full blade trip mechanisms, the full blade assembly is pivotably
mounted to the
vehicle. The pivot axis is generally located above the top of the cutting
edge. One or more
trip springs bias the two moldboards and their respective cutting edges
(which, in
conventional V-blade plows, were fixedly-, as opposed to hingedly-, secured to
the base of
the respective moldboards) into a plowing position. When an obstacle is
encountered, and
the trip spring bias is overcome, the full blade assembly pivots about the
pivot axis, which
causes the full moldboards to rotate rearward and upward, thereby clearing the
obstacle. As
with the cutting edges of edge trip mechanisms, once the obstacle has been
cleared, the full
moldboards return to their original, un-tripped position. While the full blade
trip mechanism
generally is capable of clearing relatively high obstacles, the force required
to overcome the
spring bias is greater than edge trip mechanisms, which causes greater impact
forces to be
transferred to the vehicle. These greater impact forces can be unpleasant for
a driver and any
other occupants of the vehicle.
Brief Description of the Several Views of the Drawing
[0008] Fig. 1 is a front plan view of a V-blade snowplow of the present
disclosure;
[0009] Fig. 2 is a bottom view of the V-blade snowplow of Fig. 1, illustrating
a plurality of
torsion springs that provide the snowplow with trip edge capability;
[0010] Fig. 3 is a top view of the V-blade snowplow of Fig. 1, illustrating a
plurality of trip
springs that provide the snowplow with full moldboard trip capability;
[0011] Fig. 4 is a partially-exploded front perspective view of the V-blade
snowplow of
Fig. 1;
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[0012] Fig. 5 is an enlarged bottom view of the V-blade snowplow of Fig. 1, of
the region
identified as "Fig. 5" in Fig. 2;
[0013] Fig. 6 is an enlarged rear view of a lower portion of a right wing of
the V-blade
snowplow of Fig. 1;
[0014] Fig. 7 is a front perspective view of the V-blade snowplow of Fig. 1
mounted to a
truck (shown in broken lines), immediately after making contact with an
immovable obstacle
on a roadway being plowed, the obstacle having a height lower than a height of
the cutting
edges, depicting the first (right) cutting edge, that made contact with the
immovable object,
displaced relative to the base of the respective moldboard;
[0015] Fig. 8 is a right side view of the V-blade snowplow of Fig. 1 mounted
to a truck
(shown in broken lines), with the full moldboard tripped as a result of
contact with a snow
bank;
[0016] Fig. 9 is a front-right side of the V-blade snowplow of Fig. 1 mounted
to a truck
(shown in broken lines), with the blades of the snowplow oriented in a scoop
position;
[0017] Fig. 10 is a cross-section of the V-blade snowplow of Fig. 1, with both
trip
mechanisms, i.e. the cutting edge trip and the full moldboard trip, fully
engaged;
[0018] Fig. ills a top view of the V-blade snowplow of Fig. 1 in a V position,
immediately after a cutting edge of the right wing thereof making contact with
an immovable
obstacle on a roadway being plowed, the obstacle having a height lower than a
height of the
cutting edges, depicting the first (right) cutting edge, that made contact
with the immovable
object, displaced relative to the base of the respective moldboard;
[0019] Fig. 12 is a right side view of the V-blade snowplow of Fig. 11
illustrating the first
(right) cutting edge tripping from a first orientation substantially coplanar
with a lower
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section of the respective moldboard to an angled orientation relative to the
lower section of
the respective moldboard upon impact with an immovable object;
[0020] Fig. 13 is a front view of the V-blade snowplow of Fig. 11;
[0021] Fig. 13A is a bottom view taken along lines 13A-13A of Fig. 13,
illustrating one of
the cutting edges in a tripped condition due to impact with an immovable
object and the other
of the cutting edges in an untripped condition;
[0022] Fig. 14 is a top view of the V-blade snowplow of Fig. 1 similar to Fig.
11, but
immediately after the cutting edges of both wings making contact with a
substantially
centered obstacle on a roadway being plowed, the obstacle having a height
lower than a
height of the cutting edges;
[0023] Fig. 15 is a right side view of the V-blade snowplow of Fig. 14 similar
to Fig. 12,
but illustrating neither of the cutting edges tripping but illustrating a full
moldboard trip upon
impact with the substantially centered obstacle on a roadway being plowed;
[0024] Fig. 16 is a front view of the V-blade snowplow of Fig. 14; and
[0025] Fig. 16A is a bottom view taken along lines 16A-16A of Fig. 16, similar
to Fig.
13A, but illustrating neither of the cutting edges tripping, due to the fact
that the orientation
of' the cutting edges causes them to bind on one another upon impact with a
substantially
centered obstacle or upon simultaneous impacts with a plurality of obstacles,
thereby
preventing them from tripping.
Detailed Description of the Preferred Embodiment
[0026] US Patent Nos. 4,658,519 and 7,437,839
disclose V-blade snowplows. The V-blade snowplow 10 of
the present disclosure employs the main components of those patents, as well
as
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enhancements that provide the V-blade snowplow 10 with both trip edge as well
as full
moldboard trip capabilities. While V-blade snowplows have been manufactured in
the past
with either trip edge capability or full moldboard trip capability, heretofore
there has yet to be
a V-blade snowplow that successfully offered both trip edge and full moldboard
trip.
[0027] The V-blade snowplow 10 includes a left or first wing having a first
moldboard 12
and a right or second wing a second moldboard 14, both of which are secured to
a pivot
frame 16 by a central hinge 18. A first cutting edge 20 is associated with the
first moldboard
12, and a second cutting edge 22 is associated with the second moldboard 14.
Each of the
first and second cutting edges 20, 22 may include a sacrificial element of the
V-blade
snowplow 10, in that it is made of a material intended to wear down over time
without
compromising the integrity of the respective first and second moldboards 12,
14.
[0028] Each of the first and second cutting edges 20, 22 is hingedly mounted
to its
respective moldboard 12, 14 by a plurality of trip edge springs 24 (see Fig.
5). While tension
coil springs have been employed in conventional V-plows that exhibit only trip
edge
capability, the springs 24 utilized to hingedly connect the first and second
cutting edges 20,
22 to the respective first and second moldboards 12, 14 of the V-blade
snowplow 10 of the
present disclosure are torsion trip edge springs 24 that are disposed along
the respective axes
of rotation 26, 28 of the first cutting edge 20 relative to a lower edge of
the first moldboard
12, and of the second cutting edge 22 relative to a lower edge of the second
moldboard 14. A
first end 30 of each trip edge spring 24 is secured by an anchor pin assembly
32 to a
moldboard support frame 34 of the respective moldboard 12, 14. This section of
the
moldboard support frame 34 preferably defines a bottom channel 35 therein (see
Fig. 6,
where the moldboard support frame 34 is omitted for clarity), and the
moldboard support
frame 34 at least partially shields the torsion trip edge springs 24 and
anchor pin assemblies
32 from snow, ice, and other debris. A second end 36 of each trip edge spring
24 is secured
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to a rear (i.e., truck-facing) side of the respective cutting edge 20, 22.
This is illustrated in
Figs. I and 6. The collective restoring torque of the plurality of torsion
trip edge springs 24
between a given one of the cutting edges 20, 22 and its respective moldboard
12, 14 biases
the associated cutting edge 20, 22 toward its un-tripped position. Preferably,
three torsion
trip edge springs 24 are provided in parallel (i.e., along the same hinge
axis) between each of
the cutting edges 20, 22 and its respective moldboard 12, 14, for a total of
six torsion trip
edge springs 24, as illustrated in Fig. 2.
[0029] The first and second cutting edges 20, 22 may each include a plurality
of bolt-
receiving apertures 21 along an upper edge thereof to facilitate removable
securement of
replacement cutting edges (not shown) to the first and second cutting edges
20, 22. In this
manner, a snowplow owner need not detach the first and second cutting edges
20,22 from the
torsion trip edge springs 24 when the original factory-installed cutting edges
wear to an
appreciable extent, but instead, can simply bolt replacement sacrificial edges
to the remaining
hingedly-attached portions of the original cutting edges 20, 22.
[0030] The selection of stiffness of trip edge springs 24, as well as the
stiffness of trip
springs 38 for full moldboard trip, is guided in major part by a trade-off
between the desire to
enable the cutting edge of the snowplow to trip upon contact with an immovable
object on a
roadway being plowed, on the one hand, and the desire to avoid the edge (or
the full
moldboard) tripping when plowing heavy, wet snow and ice. By providing both
trip edge
and full moldboard trip capabilities in a single V-blade assembly, the V-blade
snowplow 10
of the present disclosure can utilize stiffer trip springs (preferably four
trip springs 38
mounted in parallel) for the full moldboard trip (as compared to trip springs
of conventional
full moldboard trip-only V-blade snowplows), and stiffer trip edge springs 24,
(as compared
to conventional trip edge-only V-blade snowplows) without increasing forces
transferred to a
cab of a truck to which the V-blade snowplow 10 is secured. This is due to the
fact that the
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full moldboard trip capability and the trip edges provide back-up to one
another¨a stiffer
moldboard that is less susceptible to tripping due to heavy snow will still,
due to the
provision of trip edges, mitigate the translation of forces to the truck cab
from impacts with
stationary objects on a roadway being plowed (provided the height of those
objects is no
higher than the height of the cutting edges). By way of example only, a
suitable stiffness or
spring rate for each of the torsion trip edge springs 24 for the V-blade
snowplow of the
present disclosure is 68 lb.-in./deg., but could be higher, or lower, and a
suitable stiffness or
spring rate for each of the trip springs 38, which are extension springs as
opposed to torsion
springs, is 145 lb./in, but could be higher, or lower.
[0031] In utilizing the dual trip mode capability of the present disclosure,
impact testing
has reflected a significant reduction in forces transferred to the vehicle as
compared to
vehicles provided with snowplows having only edge trip capability. More
specifically,
between speeds of 5 to 14 miles per hour, with 14 MPH being an industry-
standard
recommended maximum plowing speed, a V-blade snowplow 10 of the present
disclosure
having dual trip mode capability experiences an average reduction of 65% of
the force
transferred to the vehicle when impacting an object with the cutting edge 20
or 22 near an
outside end of the snowplow blade 12 or 14.
[0032] The four trip springs 38 are mounted in parallel between an upper rear
portion of a
push frame 40 and a generally-horizontally extending elongate portion of a
hanger bar 42,
which hanger bar 42 is secured to a rear portion of the central hinge 18. A
turnbuckle 44 may
be provided intermediate each of the trip springs 38 and the push frame 40.
[0033] Advantageously, the full moldboard trip capability of the V-blade
snowplow 10 of
the present disclosure gives the snowplow the ability to trip, and thereby
mitigate translation
of forces upon impacts with objects of a height that is greater than the
cutting edge. This is of
particular concern to V-blade snowplow operators as the cutting edges of the
snowplow wear
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down, as the height of immovable objects over which cutting edges of a trip
edge-only V-
plow can clear diminishes as the cutting edges wear down and lose their
overall height.
[0034] Another drawback of conventional trip edge-only V-plow snowplows is
that the
angle of rotation of conventional cutting edges when tripped in a direction
rearward from the
contour of the front of the moldboard is so great, typically at least about
600, that the cutting
edges are susceptible to being stuck in their tripped condition by snow, ice,
dirt, or other
debris caught between the top of the cutting edge and the base of the
moldboard. Because the
trip edge capability is not the only means for the V-blade snowplow 10 to trip
when striking
an object, the cutting edges 20, 22 need not rotate rearward from the contour
of the respective
moldboards 12, 14 as much as conventional trip edges. For instance, the
plurality of torsion
trip edge springs 24 are preferably selected and mounted so as to permit an
angle of rotation
of the cutting edges 20, 22 relative to the respective moldboards 12, 14 in
the range of about
30 to about 40 , and preferably about 40 , i.e. about 200 smaller of an angle
of rotation than
the typical angle of maximum deflection of trip edge-only V-plow cutting
edges. As a result,
less snow, ice, or other debris can enter the region between the tripped
cutting edge 20, 22
and the base of the respective moldboard 12, 14. Moreover, by reducing the
maximum
degree of deflection through which the cutting edges 20, 22 rotate from a rest
condition to a
fully-tripped condition, the fatigue on the trip edge springs 24 is reduced.
As explained
above, the smaller degree of maximum deflection of the cutting edges 20, 22
also permits the
use of stiffer trip edge springs 24.
[0035] An additional drawback of conventional trip edge-only V-plow snowplows
is that
such snowplows, when the wings are arranged in a V, have diminished ability to
trip in
response to a center impact with an object having a height less than the
height of the cutting
edges (or even off-center impacts that would cause both cutting edges to trip
simultaneously)
due to the cutting edges at least momentarily binding with one another at the
plow center
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while attempting to rotate. The V-blade snowplow 10 of the present disclosure,
with its dual
trip capability, advantageously supplies the full moldboard trip capability
even in such
instances of center impacts where tripping of cutting edges 20, 22 is
precluded, as depicted in
Figs. 14-16A. As illustrated in Figs. 11, 12, 13, and 13A, a cutting edge 22
associated with
one of the moldboards 14 of a V-blade snowplow 10 of the present disclosure,
when the
wings of the snowplow are in a V-formation, makes contact with an obstacle 0
having a
height less than a height of the cutting edge 22. Upon contact with the
obstacle 0, the cutting
edge 22 trips by rotating rearwardly to dissipate impact forces from contact
with the obstacle
0, reducing the transmission of the impact forces to the vehicle to which the
V-blade
snowplow 10 is mounted. However, when in the V-formation and the cutting edges
20, 22
associated with both of the moldboards 12, 14 simultaneously impact one or
more obstacles
0 having a height lower than the height of the cutting edges 20, 22, as
illustrated in Figs. 14,
15, 16, and 16A, the cutting edges 20, 22 run the risk of binding against one
another, at least
momentarily preventing their tripping, but as illustrated in Fig. 15, the full
moldboard trip
capability is then triggered, thereby diminishing impact forces from the
contact with the
obstacle 0.
[0036] While the present disclosure has been described with respect to certain
embodiments, it will be understood that variations can be made thereto that
are still within the
scope of the appended claims.
