Note: Descriptions are shown in the official language in which they were submitted.
CA 02767095 2012-02-01
TOWED SNOWPLOW AND METHOD OF PLOWING
FIELD OF THE INVENTION
[0001] The present invention relates to plows and more particularly relates to
plowing arrangements for clearing snow from pavement such as a road, a highway
or a runway as well as to methods of clearing snow from pavement.
BACKGROUND OF THE INVENTION
[0002] Typically, snow is removed from pavement by a truck that is provided
with a snowplow having a moldboard that is mounted on the front end of the
truck.
Various arrangements are known for raising and lowering the moldboard of the
snow plow as desired and for changing the angle that the moldboard of the snow
plow makes with the longitudinal center axis of the truck, and therefore with
respect
to the longitudinal axis of the lane of pavement being cleared.
[0003] The moldboard of the snow plow may be selectively raised and lowered so
that the plow truck may be driven with the lowermost edge of the moldboard
either
in contact (for conducting a plowing operation) or out of contact with the
road, such
as when the truck is being driven over pavement which has already been cleared
of
snow. Also, the snow plow is typically arranged to enable the angle of the
plow
with respect to the truck to be changed so that the snow plow can be used to
divert
snow to the left or to the right of the truck or used to push snow directly in
front of
the truck such as when clearing a driveway or parking lot.
[0004] Various wing plows and other attachments are also known in the snow
removal art which effectively extend the width of the lane that can be plowed
by a
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single truck in a single pass. However, such wing plows are typically mounted
at
one side of the truck and present significant problems for the operation of
the truck
in plowing situations. For example, the use of a wing plow produces
significant
torque and disruptive forces on the truck frame and the suspension of the
snowplow
truck. Also, the maximum practical length of a wing plow is relatively small
and
does not readily permit additional lanes of pavement to be cleared of snow
during a
single pass of the snowplow vehicle.
[0005] Accordingly, the need remains for a snowplow arrangement in which a
relatively wide strip of pavement may be cleared of snow in a single pass of a
snowplow vehicle, preferably without requiring an additional operator and
without
requiring an additional vehicle.
[0006] Accordingly, the present invention provides a snowplow which is towed
by
a vehicle such as a municipal truck and which can travel at relatively high
speeds on
highways and on roads while occupying generally only one .lane of pavement or
less.
When it is desired to plow the pavement, the towed snowplow can then be
quickly
deployed to either the left or the right of the vehicle, depending upon the
configuration of the towed snowplow, to plow either to the left or to the
right of the
towing vehicle. In this way, the towing vehicle together with the towed
snowplow
can simultaneously clear several adjacent lanes of a multilane roadway system
or
highway, as well as pavement shoulders, airport runways or other wide areas.
The
towed snowplow is configured to not require an additional operator for the
towed
snowplow and so the multiple lanes of pavement may be cleared of snow in a
single
pass of the combined towing vehicle and towed snowplow using only one truck
and
one operator.
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[0007] It is a particular advantage of the preferred embodiments of the
present
invention that the towed snowplow can be transported from location to location
like
a trailer that is towed behind the motorized vehicle, such as a municipal
truck, and
then the towed snowplow can be deployed to the right (or left depending upon
the
configuration of the towed snowplow) using steering axles or pivoting axles to
cause
the trailer to swing out to one side of the towing truck. The towed snowplow
automatically deflects or slides in the event that the towed snowplow blade(s)
or
moldboard(s) strike an obstacle, without incurring major damage to either the
towed
snowplow or to the towing vehicle.
[0008] In the preferred embodiments of the towed snowplow according to the
present invention, roads and highways may be more quickly cleared of snow and
other winter precipitation which improves safety by reducing accidents and by
reducing the number of stranded vehicles and travelers. Because the towed
snowplow does not require a second operator in the towing vehicle, the
preferred
embodiments of the present invention improve efficiency and production for
snow
clearing operations and reduce the need for additional numbers of snowplow
trucks
and operators.
[0009] The preferred embodiments of the present invention enable snow plow
operations to also plow soft shoulders of roadways without placing the
snowplow
truck physically onto the shoulder of the pavement. In addition, plowing
operations
in mountainous situations are relatively safer because the snowplow truck may
maintain a safer distance from the outside edge of the pavement and thereby
more
easily avoid inadvertently driving off of the roadway.
=
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[0010] The wide plowing capability of the preferred embodiments of the present
invention enables the towing vehicle and towed snowplow to plow irregular
cross
sections more quickly and efficiently as well as providing an arrangement to
cut,
blow or squeegee pavement by using two cutting edges.
[0011] Specifically, the towed snowplows according to the preferred
embodiments
of the present invention are much safer to use than conventional front and
side
(wing) plows which may be mounted on the front, the middle, or the rear of
snowplow trucks. These conventional side (wing) plows can present major
dynamic
loads on the plow, as well as on the push frames and the truck frames, on the
chassis
of the snowplow, as well as on the axles and wheels of the snowplow truck.
[0012] The towed snowplow according to the present invention can strike
relatively large or even permanent obstacles and deflect without causing great
stress
to the towing vehicle.
[0013] The preferred embodiments of the present invention can be used to plow
more safely at relatively higher speeds than most or all conventionally known
snowplows, while being stable, when compared to side or wing plows, which
often
tend to hop, lope, bounce or porpoise. In this way, the towed snowplow
according
to the present invention is suitable for use at relatively higher speeds while
plowing
on interstate highways as well as on high speed expressways.
[0014] Side or wing plows also cause significant loading on their deployed
side
while simultaneously causing the other side of the snowplow truck to become
relatively much lighter. If a side or wing plow is relatively large, it can
often
overload the tires of the snowplow truck especially on the side of the truck
where the
side or wing plow is deployed. Overloading of the tires and the suspension of
a
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snowplow truck presents a safety hazard and is likewise illegal in many
states. The
towed snowplow according to the preferred embodiments of the present invention
does not overload the front steering axles of the towing vehicle as can occur
with
side or wing plows.
[0015] It is also common in some situations to initially plow the pavement or
highway surface so as to remove snow. Subsequently, the snowplow truck is used
to
plow the shoulders of the roadway. This practice places the snowplow truck
(typically heavily loaded with salt or sand or gravel) upon the dirt, sod or
improved
shoulder of the roadway. However, the heavily loaded trucks can make ruts in
soft
shoulders or can damage seal coats or other improved shoulders. The towed
snowplow of the present invention can be used to plow highway shoulders
without
placing the loaded towing truck physically onto the shoulder, thus reducing
shoulder
damage.
[0016] The preferred embodiments of the present invention also enable the
towed
snowplow to be moved from one site to the next (while not in a deployed or
plowing
configuration) while located within a single conventional lane of traffic and
without
encroaching outside of the lane like wing plows and other conventionally known
plowing systems.
[0017] The towed snowplow according to the present invention may have one or
more moldboards totaling generally from 10 feet to 40 feet or more which may
be
towed directly behind the towing vehicle from a storage location such as a
maintenance shop to the pavement to be plowed.
[0018] In the preferred embodiments of the present invention, the towed
snowplow
is steered from the driver's seat of the towing vehicle which allows the
driver or
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operator of the snowplow truck to selectively deploy and retract the towed
snowplow from the transport position (directly behind the towed vehicle) to
the
plowing position (diagonally behind the vehicle) in 200' or less.
[0019] In addition to moving the towed snowplow between the transport position
and the deployed position, the steering of the towed snowplow can also be used
to
= cause the plow to favor the left or right side during transport or to
steer and negotiate
the towed snowplow around hard turns. Typically during relatively gradual
curves,
such as are common on major highways and interstate road systems, the towed
= snowplow will remain in either the transport position or in the deployed
position
without additional steering.
= [00201 During a plowing operation, the driver or operator of the vehicle
can easily
vary the plowing width of the towed snowplow such as to accommodate turn lanes
or temporary increases or decreases in pavement widths. When in the deployed
position, the towed snowplow of the present invention is stable at any desired
angle
with respect to the towing vehicle.
= [0021] The towed snowplow according to the present invention can be
easily
steered around obstacles and then returned to its plowing or deployed
position.
Accordingly, the towing truck may remain in one lane of pavement without
deviating and the operator may use the towed snowplow to plow around an
obstacle
such as a parked vehicle located on the highway shoulder. After passing the
obstacle, the operator may rapidly return the towed snowplow to resume the
plowing
of one or more additional lanes of pavement. In addition, the towed snowplow
is
able to pivot around or easily pass over obstructions such as raised pavement
markers, joints and other obstacles. =
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[0022] The towed snowplow can easily hook to conventional dump trucks,
especially to municipal snowplow trucks, which have pintle hitches. Front and
side
plows typically require the installation of additional hardware that is
attached or
otherwise hooked to the truck frames or to bumpers. The towed snowplow of the
present invention, however, can use the standard hitches normally used by
trucks for
pulling pups or trailers along with the standard hydraulic and electrical
hookups
conventionally provided on such trucks for use with towed trailers.
SUMMARY OF THE INVENTION
[0023] In the present invention, a snowplow is arranged to be towed behind a
vehicle, with the snowplow comprising a frame having a longitudinal axis. The
frame is carried by at least one wheel and preferably by four wheels or more
arranged about at least two axles. The wheel or wheels are selectively movable
between a first position and a second position, with each wheel being
generally
aligned with the longitudinal axis of the frame when the wheel is in the first
'position
and the wheel is selectively angled with respect to the longitudinal axis of
the frame
when the wheel is in the second position. The frame carries at least one
moldboard
which is used to plow snow when the device is in the second position.
[0024] In the preferred embodiments, the frame of the snowplow may be
pivotably
connected to a vehicle whereby the frame may be towed by the vehicle. The
wheel
or wheels are remotely steerable, preferably from within the vehicle, and the
moldboard may be selectively raised and lowered.
[0025] In the preferred embodiments of the present invention, a snowplow which
is arranged to be towed behind a vehicle, comprises a frame having a
longitudinal
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axis. The frame is carried by a plurality of wheels which are selectively
movable
between a first position and a second position. Each wheel is generally
aligned with
the longitudinal axis of the frame when the plurality of wheels is in the
first position
and each wheel is selectively angled with respect to the longitudinal axis of
the
frame when the plurality of wheels is in the second position. A plurality of
moldboards is carried by the frame. Preferably, the frame is pivotably
connected to
a vehicle whereby the frame may be towed by the vehicle. The frame may be
towed
generally directly behind the vehicle when the plurality of wheels is in the
first
position and the frame may be towed generally diagonally with respect to a
centerline of the vehicle when the plurality of wheels is in the second
position. The
frame preferably defines a length and a width, with the plurality of
moldboards
together extending generally along the entire length of the frame and the
plurality of
moldboards may be selectively raised and lowered with respect to the frame. In
addition, it is preferable that each of the plurality of moldboards may be
selectively
raised and lowered with respect to the frame from within the vehicle. The
snowplow preferably defines an overall width and an overall length, with the
overall width of the snowplow being about 102 inches or less. Likewise, the
plurality of moldboards together preferably define an overall length
sufficient to
plow at least 120 inches of pavement.
[0026] The preferred embodiments of the present invention also include a
combination snowplow truck and towed snowplow, comprising a truck which is
provided with a front moldboard having a front moldboard which may be
selectively _
raised and lowered. The towed snowplow comprises a frame which is pivotably
connected to the truck at a rear end of the truck. The frame has a
longitudinal axis
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and a plurality of wheels. The frame is carried by several wheels which are
selectively movable between a first position and a second position. Each wheel
is
generally aligned with the longitudinal axis of the frame when the wheels are
in the
first position and each of the wheels is selectively angled with respect to
the
longitudinal axis of the frame when the plurality of wheels is in the second
position,
and a plurality of moldboards is carried by the frame.
[0027] In the preferred embodiments of the combination snowplow truck and
towed snowplow, the frame is towed generally directly behind the truck when
the
plurality of wheels is in the first position and the frame is towed generally
diagonally with respect to a centerline of the truck when the plurality of
wheels is in
the second position.
[0028] In a method of plowing snow from pavement according to the present
invention a frame is towed behind a vehicle from a rear hitch with the frame
being
carried by at least one wheel. The frame is moved from a transport position
with the
= frame positioned directly behind the vehicle to a deployed position in
which the
frame extends diagonally from the rear hitch of the vehicle. As desired,= at
least one
= moldboard carried by the frame is lowered into a plowing position. The
moldboard
is then used to plow snow from pavement in a path alongside the vehicle.
Subsequently, as desired, the moldboard is raised out of the plowing position
and the
frame is moved from the deployed position back to the transport position.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0029] The present invention will appear more clearly from the following
detailed
description of several embodiments illustrated in the enclosed figures in
which:
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[0030] Fig. 1 is a top view of a towing vehicle and a towed snowplow in the
deployed position according to the present invention;
[0031] Fig. 2 is a top view of the towing vehicle and towed snowplow of Fig.1
with the towed snowplow in a transport position behind the towing vehicle;
[0032] Fig. 3 is a side view of a modified version of the towing vehicle and
towed
snowplow of Fig. 1 according to another preferred embodiment of the present
invention;
[0033] Fig. 4 is a right side view of the towing vehicle arid towed snowplow
of
Fig. 1 showing the moldboard side of the towed plow in the transport position;
[0034] Fig. 5 is a left side view of the towing vehicle and towed snowplow of
Fig.
1 in the transport position;
[0035] Fig. 6 is a front view of the towing vehicle and towed snowplow of Fig.
1
with the towed snowplow in the deployed position;
[0036] Fig. 7 is a rear view of the towing vehicle and towed snowplow of Fig.
1
with the towed snowplow in the deployed position;
[0037] Fig. 8 is a front view, of the towing vehicle and towed snowplow of
Fig. 1
with the towed snowplow in the transport position;
[0038] Fig. 9 is a rear view of the towing vehicle and towed snowplow of Fig.
1
with the towed snowplow in the transport position;
[0039] Fig. 10 is a top view of the towed snowplow of Fig. 1 towed in the
deployed position by a vehicle provided with a front snowplow;
[0040] Fig. 11 is a side view of the arrangement of Fig. 10;
[0041] Fig. 12 is a top view of the towed snowplow of Fig. 1 towed in the
transport position by a vehicle provided with a front snowplow; and,
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[0042] Fig. 13 is a side view of the arrangement of Fig. 12.
DETAILED DESCRIPTION OF THE INVENTION
[0043] With reference to Fig. 1, a towed snowplow 100 according to the present
invention includes a frame 102 which is carried by at least one wheel 104. In
the
preferred embodiment, the frame 102 is a rectangular structure having a length
and a
width. Preferably, the frame is relatively long and relatively narrow in order
to
minimize the width of the towed snowplow when being transported directly
behind a
towing vehicle 106 while enabling the towed snowplow to plow a significantly
wide
strip of pavement when in a deployed position.
[0044] In Fig. 1, the towing vehicle 106 may typically be a snowplow truck
with
or without a front moldboard (see Fig. 10). The conventional municipal or
commercial snowplow truck typically is provided with a pintle hitch for towing
a
trailer or other device along with hydraulic lines as well as air brake lines
and
electrical wiring for brake lights and warning lights to accommodate
conventional
trailers and other devices configured to be towed behind the truck.
[0045] The frame 102 preferably has an arm 108 or extension that extends
parallel
to a centerline of the towed snowplow to facilitate connection of the frame to
the
pintle hitch or other towing connection of the truck. The frame is preferably
relatively lightweight and may be formed from conventional box beams or other
structural members but the frame is preferably sufficiently rigid to provide
adequate
support for a series of moldboards 110 carried by the frame 102.
[0046] In the preferred embodiment of Fig.1, the towed snowplow is provided
with three generally identical moldboards 112 which are mounted on the frame
in a
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= side by side rummer so as to effectively present a single moldboard
during plowing
operations. A suitable, conventional arrangement for mounting the moldboards
on
the frame of the towed snowplow is provided along with an arrangement for
selectively raising and lowering the moldboards with respect to the frame 102
and,
more importantly, with respect to the pavement to be plowed.
[0047] The frame 102 in the preferred embodiment is carried by four wheels 104
= which are mounted on a sub-frame 114 which enables the wheels to be
steered
relative to the sub-frame 114 and relative to the frame 102 of the towed
snowplow.
The four wheels 104 preferably comprise suitable, conventional steerable front
wheels such as may be found on a snowplow truck.
[0048] Although the preferred embodiment includes two steerable axle
arrangements mounted one behind the other, the towed snowplow may also have
only a single wheel or only a single pair of wheels, especially if some
arrangement is
provided to maintain the frame in a substantially horizontal configuration. In
the
preferred embodiment, four wheels are arranged about two axles in order to
provide
a stable platform for maintaining the frame in a generally horizontal position
especially when the moldboards are in a raised position which provides a
torque
about the longitudinal axis of the frame. Moreover, the towed snowplow may
have
more than four wheels, each of which is steerable, if desired, especially in
= embodiments in which the length of the towed snowplow is relatively long.
[0049] Although the preferred embodiments of the towed snowplow include
steerable wheels, the towed snowplow may have one or more wheels with a fixed
orientation relative to the sub-frame 114. An arrangement such as a ring gear
and
drive motor is provided between the sub-frame 114 and the frame 102 to rotate
the
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sub-frame 114 relative to the frame 102. In this way, the wheel or wheels may
be
effectively "steered" by moving the subframe relative to the frame 102 to move
the
towed snowplow between a transport position directly behind the towing vehicle
and
a deployed position for plowing operations.
[0050] The three moldboards 112 may be configured so as to be raised and
lowered simultaneously or individually, as desired. In addition, the
moldboards 112
may be mounted on the frame 102 using any suitable, conventional mounting
arrangement such as is known in the art for front moldboards. For example, the
moldboards may be mounted to the frame using resilient members (such as
urethane) which are received within a mounting member so as to enable mounting
arms and the moldboard to pivot about the mounting member in the event that an
obstruction is encountered by the moldboard such as is disclosed in U.S:
Patent No.
6,219,943, U.S. Patent No. 6,354,025, and U.S. Patent No. 6,536,141 of the
assignee
Cives Corporation.
[0051] In the embodiment of Fig. 1, the wheels 104 have been turned (or
steered)
so as to have the plane of each of the wheels angled with respect to a
longitudinal
axis of the towed snowplow. As a result, the towed snowplow will move from a
transport position directly behind the towing vehicle 106 (see also, Fig. 2)
to a
deployed position in which the towed snowplow forms an angle with respect to
the
towing vehicle about the pivot connection of the frame 102 with the truck.
[0052] Preferably, the leading edge of the moldboards 112 extends to generally
the
outside edge of the strip of pavement plowed by a front moldboard mounted on
the
towing vehicle (see Fig. 10). The moldboard of the towed snowplow in the
configuration of Fig. 1 can then plow one or more additional lanes of pavement
to
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the right side of the towing vehicle, depending upon the length of the towed
snowplow 100 and the angle of the towed snowplow with respect to the vehicle.
[0053] With reference now to Fig. 2, when the plane of each of the wheels 104
is
aligned with the centerline of the vehicle 106, the towed snowplow will assume
the
transport position in which the towed snowplow is directly behind the towing
vehicle. In order to facilitate transport of the towed snowplow without undue
disruption of traffic and to comply with various width restrictions on
interstate
highway systems, it is preferably that the overall width of the towed snowplow
be
generally the same as the width of the towing vehicle or less. As shown in
Fig. 2,
the towed snowplow may extend slightly beyond the overall width of the towing
vehicle while still satisfying the width restrictions for various highway
systems.
[0054] With reference now to Fig. 3, the towed snowplow 100 preferably has an
arrangement of warning lights 114 which are preferably mounted at the trailing
end
of the towed snowplow. If desired, the arrangement of warning lights may be
mounted on a rotatable mounting post 116 which is arranged to rotate with the
movement of the wheels 104. In this way, the arrangement of warning lights 114
will directly face the oncoming traffic regardless of the position of the
towed
snowplow with respect to the towing vehicle. In addition, warning lights (not
shown) may be provided along the length of the frame 102 to provide additional
notice to following traffic of the towing operation. Those warning lights are
mounted on the left side of the towed snowplow of Fig. 2 in order to be
directed
rearwardly when the towed snowplow is in the deployed position (see Fig. 1).
[0055] With continued reference to Fig. 3, the towed snowplow may also be
provided with one or more bins or tanks or compartments 118 which are
preferably
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mounted directly over the axles and the tanks should maintain a low center of
_ gravity, mounted as low as possible in order to provide
ballast and additional
traction especially in icy pavement conditions. The compartments 118 may
contain
= salt, sand, gravel, or a deicing fluid which is arranged to be sprayed or
distributed
behind the moldboards 112, as desired, such as by spinners 120.
[0056] With reference now to Fig. 4, the towed snowplow is shown in the
transport position with the moldboards raised relative to the pavement to be
plowed.
If desired, arms 122 may be provided above each of the moldboards 112 to
facilitate
raising and lowering of the moldboard on the towed snowplow (see also Figs. 6
and
7). The arms 122 are raised and lowered by hydraulic cylinders 123 provided
for
each arm 122.
[0057] With reference now to Fig. 5, the left side of the towed snowplow and
towing vehicle is shown. If desired, fenders (not illustrated) may be provided
for the
wheels of the towed snowplow.
[0058] In Figs. 6 and 7, the front and rear views of the towed snowplow in the
deployed position are illustrated with the moldboards still in the raised
position. In
order to perform a plowing operation, the moldboards would be lowered so as to
= haV'e the lowermost edge of the moldboard contact the pavement or,
roadway.
[0059] In Fig. 7, an arrangement for mounting the moldboards on the frame is
shown although various other suitable, conventional arrangements for mounting
the
moldboards on the frame will be readily apparent to one skilled in the art of
snowplows. In general, support members 124 and 126 are provided to orient
upper -
and lower portions of the moldboard with respect to the frame so as to
position the
moldboard in a desired configuration. for efficient plowing.
=
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[0060] With reference to Fig. 8, a front view of the towing vehicle with the
towed
snowplow in the transport position is shown. In the embodiment of Fig. 8, the
left
side wheels of the towed snowplow extend slightly beyond the left edge of the
vehicle and similarly the leading edge of the moldboard(s) extends slightly
beyond
the right edge of the vehicle. If desired, the towed snowplow may be
configured
more narrowly so as not to extend beyond the overall width of the towing
vehicle.
In any event, it is generally desirable that the overall width of the towed
snowplow
be less than about 102 inches so as to comply with typical interstate highway
system
width requirements.
[0061] With reference to Fig. 10, a towing vehicle and towed snowplow
arrangement is shown in which the towing vehicle includes a front plow 130.
The
front plow 130 includes a moldboard 132 which may be oriented at various
angles
relative to the vehicle to accommodate different plowing situations.
Typically, the
width of the front moldboard will be equal to or slightly greater than the
overall or
effective width of the towed snowplow when in the transport position.
[0062] If desired, the steering may be configured so that in the event of a
loss of
steering control (such as a loss of hydraulic fluid to the steering mechanism
for the
wheels), the wheels will automatically assume the transport position so that
the
towed snowplow will move to the transport position directly behind the towing
vehicle. Additionally, the towed snowplow may be provided with its own power
unit or with an electrical steering mechanism that may be radio controlled. It
is
desirable, however, that the towed snowplow be steerable from the cab of the
towing
vehicle so that an additional operator is not required for the towed snowplow.
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[0063] To perform a plowing operation using the towed snowplow of the present
invention, the snowplow is pivotably connected to the towing vehicle and the
one or
more wheels are placed in the transport position with the plane of the wheels
aligned
with the longitudinal axis of the towed snowplow. In this configuration, the
towed
snowplow may be transported by the vehicle to a location where the plowing
operation is to commence. When desired, the operator of the towing vehicle
causes
the wheels to move to a deployed position in which the plane of the wheels
makes
an angle generally between 0 degrees and 90 degrees and more preferably
between
about 0 degrees and 45 degrees and most preferably about 45 degrees with
respect to
. _
the longitudinal axis of the towed snowplow. As a result, the towed snowplow
moves from the transport position to the deployed position generally diagonal
with
respect to the towing vehicle. When desired, the moldboard(s) are then lowered
and
the plowing operation commences. When desired, the moldboard(s) are lifted
and.
the wheels are moved back to the transport position which causes the towed
snowplow to move from the deployed position to the transport position directly
.
behind the towing vehicle.
10064] In the preferred embodiments of the present invention, the towed
snowplow
is configured to plow either to the left or to the right of the towing
vehicle.
However, the towed snowplow could also be arranged to plow, both to the right
and
left of the towing vehicle. Especially if the towed snowplow may exceed the
width
of a standard lane of traffic (such as 12'), the towed snowplow can be
equipped with
both left and right moldboards either on a single frame or on separate
complementary frames which can be deployed to either side of a towing vehicle_
For example, such an arrangement would be particularly suitable for use in
clearing
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strips of pavement such as airport runways. The left and right towed snowplows
could be towed by a common hitch arrangement on the vehicle or the towing
vehicle
could be provided with two different hitch arrangements to tow left and right
towed
snowplows. In addition, the left and right towed snowplows may each be
independently deployed to a plowing position behind the vehicle. In this way,
the
vehicle 'could be used as desired to plow to the left of the vehicle, to the
right of the
vehicle or to both the left and right of the vehicle simultaneously. =
[0065] The left and the right towed snowplows may be relatively narrow in
construction and may have the wheel arrangements in complementary positions so
that the two towed snowplows may have a combined width of only one lane of
. traffic when in the transport configuration. In such a configuration, the
left and right
towed snowplows may have an extendable connection between the two towed
= snowplows, if desired, to maintain the diagonal orientation of the
snowplows with
respect to the vehicle during .a plowing operation.
= [0066] If desired, the wheels for the towed snowplow may be provided ma
subframe or carriage which is. rotatable relative to a mainframe which carries
the
moldboards. For example, the subframe or carriage may have a ring gear which
is.
= driven by a geared motor mounted on the mainframe. of the towed snowplow.
By
using the motor to rotate the ring gear, the orientation of the subframe or
carriage
relative to the mainframe may be varied to move the towed snowplow from the
= transport position to a deployed position and back again.
[0067] The towed snowplow according to the present invention may be equipped
with more than one cutting edge. For example, the towed snowplow may have a
first moldboard (or series of first moldboards extending along the length of
the
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towed snowplow) with a steel edge. In addition, another moldboard (or series
of
second moldboards) with a rubber or squeegee edge may be provided on the towed
snowplow. Likewise, if desired, a blowing system may be provided on the towed
snowplow with any associated power unit mounted on the towed snowplow or on
the towing vehicle as desired.
[0068] In the preferred embodiments of the towed snowplow according to the
present invention, the towed snowplow may preferably be operated at an angle
with
respect to the towing vehicle of about 45 degrees or less. Typically, a front
mounted
moldboard on a vehicle has a normal plowing angle of about 45 degrees up to
about
60 degrees. Accordingly, the towed snowplow provides additional safety during
plowing operations because bridge expansion and other expansion joints are
generally oriented at about 60 to 90 degrees with respect to a centerline of a
highway. As a result, front plows, wing plows and underbody plows have a
cutting
angle which often matches the expansion joint angle. By operating a towed
snowplow according to the present invention at an angle of about 45 degrees or
less
with respect to the towing vehicle, the likelihood that the towed snowplow
moldboard edge will fall into such joints is significantly reduced.
[0069] As desired, the towed snowplow according to the present invention can
be
deployed not only onto the shoulder but also either down or up slopes which
extend
beyond the edge of the pavement or shoulder being plowed. In this way, areas
not
typically accessible to plowing by front plow moldboards and side wing
moldboards
may be cleared of snow which accordingly provides additional adjacent storage
room along the roadway for drifting snow and to facilitate future plowing.
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[0070] The towed snowplow may be provided with one or more storage
containers, preferably generally above the wheel or wheels of the towed
snowplow
to provide additional traction and reduce slipping and sliding of the towed
snowplow. Such storage containers may have associated spraying or discharging
arrangements to distribute salt, sand, gravel or deicing compositions during
the
plowing operation. In addition, the storage containers on the towed snowplow
may
likewise provide the plowing truck with an additional payload of salt, brine
or other
materials in liquid or solid form.
[0071] Accordingly, the towed snowplow according to the present invention when
hooked to one truck and using one operator can clear in one pass the amount of
pavement cleared by two or more trucks (and two or more operators) not
equipped
with towed snowplows in plowing situations.
[0072] As desired, the towed snowplow can be unhooked from the towing vehicle
and left, for example for blade change out or for repair, while permitting the
truck to
continue plowing operations with the vehicle's front plow. Because of its
relatively
narrow width, the towed snowplow according to the present invention can be
pulled
into maintenance shops through typical conventional door for accommodating
plowing vehicles. If the vehicle's front plow is disabled or removed such as
for
service, the towed snowplow can remain on the truck and continue to be used
for
plowing operations.
[0073] The towed snowplow can be used by state, municipal or federal
transportation departments or other agencies, yet, if desired, be hooked to
private or
commercial trucks by using their pintle or other hitches, without requiring
unusual
or specific mounting equipment or configuration on the towing vehicle. During
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significant snow storms, governmental agencies typically need to pay for
mounting
and removing specialized equipment on contractors' trucks. These charges may
be
avoided since the towed snowplow according to the preferred embodiments of the
present invention do not require the towing vehicle to have any unusual or
specific
equipment to tow and steer the towed snowplow.
[0074] Because the towed snowplow preferably has a plurality of moldboards
provided along the length of the snowplow, the towed snowplow is able to
generally
contour to the roadway cross section and as well to inslopes.
[0075] Towed snowplows having a relatively shorter length of about 10' to 30'
can be used to clear mainline and shoulders in one pass at high speeds, (i.e.,
speeds
generally over about 40 MPH). Relatively longer towed snowplows having a
length
of about 40' or more can clear over 30' when pulled by a towing vehicle which
has
a front plow, thus replacing two or more trucks for runway and other surfaces.
If
desired, the towed snowplow (especially the longer towed snowplows) may be
provided with brakes actuated either automatically with the vehicle's brakes
or
independently. Similarly, it may be desired or necessary to provided the
relatively
long towed snowplows (especially those over 40' long) with full time ballast
to
reduce side drift. As desired, the wheel or wheels of the towed snowplow may
be
provided with chains or cables and may be configured as driven wheels to
assist in
the plowing operation.
[0076] The towed snowplow should be provided with adequate lighting and safety
signage to alert other vehicles of the plowing operation and to prevent or
discourage
vehicles from following too closely or from attempting to pass the vehicle and
the
towed snowplow.
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[0077] The towed snowplow according to the present invention is particularly
suitable for use in mountainous situations. In such use, if the towed snowplow
is
deployed and slides off the slope, the natural tendency of the moldboard is to
cut
into the shoulder point and ski directly toward the hitch point of the towing
vehicle.
The relatively light weight of the towed snowplow will allow the considerably
heavier truck to pull the towed snowplow back into the deployed position or
back
into a towed position without difficulty.
[0078] The towed snowplow can be towed behind a plow truck while negotiating
the tightest of turns especially if the towed snowplow is equipped with left
and right
steering for the wheels.
[0079] For safety reasons, in the configuration shown for deployment to the
right
of the vehicle, the towed snowplow is normally restricted to only a 3 to 5
degree left
steering and full right steering. In mountain switch back situations, the left
steering
can unlock and be used to negotiate curves and turns.
[00801 The towed snowplow steering can also be used to facilitate backing of
the
towed snowplow as well as towing in tight situations. If desired, a mirror
image of
the illustrated right side towed snowplow can be provided for a towing vehicle
so as
to enable plowing of left passing shoulders. Especially in mountain plowing
operations, a relatively small configuration of the towed snowplow may be
desirable
to plow to the right of the vehicle beyond the edge of the front plow without
jeopardizing the towing vehicle. The towed snowplow can quickly recover
because
the cutting edge and towed snowplow ski will automatically cause the towed
snowplow to seek the direction of the truck hitch.
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[0081] In airport plowing operations, a tandem towed snowplow arrangement can
be deployed to allow one truck and one operator to clear 60 or more feet with
only
one truck. The relatively wide clearing path allows the towing vehicle and
towed
snowplow to quickly clear light snow between aircraft landings. The towed
snowplow can incorporate a blower to compliment the moldboard cutting edge or
to
blow snow off a runway.
[0082] In parking lot plowing, the relatively light weight of the towed
snowplow
can be used by smaller trucks to plow parking lots as well as by trucks which
do not
have front plows.
[0083] The principles, preferred embodiments and mode of operation of the
present invention have been described in the foregoing specification. However,
the
invention which is intended to be protected is not to be construed as limited
to the
particular embodiments disclosed. The embodiments are therefore to be regarded
as
illustrative rather than as restrictive. The scope of the claims should not be
limited
by the preferred embodiments set forth in the examples above but should be
given the
broadest interpretation consistent with the Description as a whole.
