Note: Descriptions are shown in the official language in which they were submitted.
CA 02591166 2007-06-15
MATERIAL TRANSFER VEHICLE FOR USE IN ASPHALT PAVING
FIELD OF THE INVENTION
The present invention relates generally to a self-propelled vehicle that is
adapted for transferring
asphalt from a supply truck to an asphalt paving machine.
BACKGROUND OF THE INVENTION
Paving of roadways with asphalt is generally carried out by an asphalt paving
machine and a
number of supply trucks which transport the asphalt from an asphalt production
plant to the
paving machine. The paving machine generally is self-propelled and driven by a
wheeled or
tracked drive system. A hopper is located at the front end of the machine to
receive asphalt from
a truck, and a floating screed is located at the rear end of the machine to
form the asphalt mat. A
conveyor system typically comprised of slat conveyors and screw augers
delivers the asphalt
from the hopper to the road base just ahead of the screed.
A typical asphalt paving machine has a hopper with a capacity of 5-15 tons,
whereas a typical
dump-type delivery truck has a capacity of about 20 tons. The front of the
paving machine is
usually provided with rollers which are adapted to engage the rear tires of a
delivery truck. This
CA 02591166 2007-06-15
arrangement enables asphalt to be transferred from the truck to the asphalt
paving machine by
positioning the delivery truck in front of the paving machine and raising the
dump bed of the
truck to dump the asphalt into the hopper as the paving machine pushes the
truck along in front
of it. Because the delivery truck usually carries more asphalt than the hopper
can receive at one
time, the paving machine may push the delivery truck along for several minutes
while its
conveyor system transports the asphalt out of the hopper to the roadway in
front of the screed.
Sometimes, problems may arise when operating the paving machine and the
delivery trucks in
this manner. Because of traffic conditions and other unforeseen delays, it is
not uncommon for
the paving machine to empty its hopper of asphalt before a loaded delivery
truck is available to
begin dumping its asphalt into the hopper. When this occurs, the paving
machine must stop
paving and await the arrival of another delivery truck. Even if one or more
loaded delivery
trucks are available to dump asphalt into the paving machine hopper, it may be
necessary to stop
the paving machine. Sometimes, it is simply impossible for the truck drivers
to remove an empty
delivery truck from engagement with the front of the paving machine and to
maneuver a loaded
truck into position to dump into the hopper before the hopper is emptied.
As is known to those having ordinary skill in the art to which the invention
relates, when a
paving machine stops, even for a short time, the screed will tend to settle
into the freshly laid
asphalt mat. Then, when the paving machine resumes its forward motion, the
screed will tend to
ride upwardly momentarily, thus depositing an excessive amount of material.
Consequently,
stopping of the paving machine causes a depression and a bump in the surface
of the asphalt mat,
resulting in an uneven pavement surface. Consequently, in recent years,
material transfer
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vehicles have been employed to shuttle asphalt between the delivery trucks and
the paving
machine. Such a material transfer vehicle is described in various embodiments
in U.S. Patents
No. 4,818,139, No. 5,015,120 and No. 5,035,534, which are incorporated herein
by reference.
These patents describe a self-propelled material transfer vehicle which
includes a large-capacity
truck-receiving hopper and a large-capacity truck-unloading conveyor extending
from this
hopper to a surge bin that is sized to hold the entire load of a delivery
truck. A conveyor in the
surge bin is adapted to transfer asphalt to a paver-loading conveyor that is
pivotable about an
essentially vertical axis so that the transfer vehicle can be positioned
alongside an asphalt paving
machine that is laying an asphalt mat and rapidly discharge a truckload of
asphalt into the paver's
hopper. Because of its rapid loading and unloading capabilities, the material
transfer vehicle can
rapidly shuttle between delivery trucks at a pick-up point and a paving
machine that is laying an
asphalt mat so that there is less likelihood that the paving machine will have
to stop paving
because of a lack of asphalt.
Although this material transfer vehicle has met with much commercial success,
it would be
desirable if its weight could be reduced, and if other advantageous features
could be incorporated
into an improved material transfer vehicle.
ADVANTAGES OF THE INVENTION
Among the advantages of the invention is that it provides a material transfer
vehicle which does
not require three conveyors as does the prior art vehicle. Consequently, the
improved vehicle of
the invention is somewhat less complex and may have a significantly reduced
weight. An
advantage of a preferred embodiment of the invention is that it provides a
four-wheeled material
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transfer vehicle in which both front and rear wheels are steerable for
improved maneuverability.
Ariother advantage of apreferred embodiment of the invention is that it
provides such a vehicle
with improved asphalt remixing capability in the surge bin.
Other advantages and features of this invention will become apparent from an
examination of the
drawings and the ensuing description.
EXPLANATION OF TECHNICAL TERMS
As used herein, the term "aggregate materials" refers to crushed stone and
other particulate
materials that are used in the production of asphalt, such as, for example,
crushed limestone and,
other types of crushed stone, crushed or comminuted recycled asphalt paving
materials, crushed,
shredded or comminuted shingles and other asphalt binder-containing products,
shredded or
comminuted mineral and cellulosic fibers, gravel, sand, lime and other
particulate additives.
As used herein, the term "asphalt binder" refers to a dark brown to black
solid or semi-solid
cementious material which gradually liquefies when heated, in which the
predominating
constituents are bitumens, all of which occur in the solid or semi-solid form
in nature or are
obtained by refining petroleum, which is used in the production of asphalt.
As used herein, the term "asphalt" refers to a bituminous paving mixture that
is comprised of
asphalt binder and any of various aggregate materials, and which is used for
paving purposes.
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As used herein, the terms "asphalt paving machine", "paving machine", "paver"
and similar
terms refer to a finishing machine for applying asphalt to form. an asphalt
mat on a roadway,
parking lot or similar surface. An asphalt paving machine is typically a self-
propelled vehicle
having a hopper at one end for receiving asphalt and a screed at the other end
for forming an
asphalt mat.
As used herein, the term "asphalt mat" refers to a layer of asphalt such as is
applied by an asphalt
paving machine to produce a roadway, parking lot or similar surface.
As used herein, the terms "delivery truck", "truck" and similar terms refer to
a vehicle for
transporting asphalt along a roadway, which vehicle is adapted to transfer
asphalt to a hopper that is
mounted on a material transfer vehicle or a paving machine.
As used herein, the terms "forward", "front" and similar terms, when used in
connection with a
material transfer vehicle, a component of such vehicle or a position on such a
vehicle, refer to the
end of the machine nearest the truck-receiving hopper. The terms "backward",
"rear" and similar
terms, when used in connection with such a vehicle, component or position,
refer to the end of the
vehicle opposite the front end.
As used herein, the term "rotary actuator" and similar terms refers to an
electric, hydraulic or
electro-hydraulic device that generates force that is directed along an arc.
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As used herein, the term "linear actuator" and similar terms refers to an
electric, hydraulic or
electro-hydraulic device that generates force that is directed in a straight
line. One common
example of a linear actuator is a hydraulic cylinder which includes a
cylinder, a piston within the
cylinder, and a rod attached to the piston. By increasing the pressure within
the cylinder on one
side of the piston (over that on the opposite side of the piston), the rod
will extend from the
cylinder or retract into the cylinder.
As used herein, the term "actuator" and similar terms refers to a rotary
actuator and/or a linear
actuator.
SUMMARY OF THE INVENTION
The invention comprises a material transfer vehicle for transporting asphalt
from a delivery truck
to a paving machine. This vehicle includes a frame and a vehicle drive system
which is
operatively attached to the frame and adapted to drive the vehicle. A turret
is rotatably mounted
on the frame, and a surge bin, which is adapted to contain a quantity of
asphalt, is mounted on
the turret. The surge bin has a front side and a rear side with a discharge
opening in the rear side.
The vehicle also includes a truck-unloading conveyor that is mounted on the
frame. The truck-
unloading conveyor has an inlet end and an outlet end which is adjacent to the
front side of the
surge bin. The truck-unloading conveyor is adapted to move asphalt from the
inlet end to the
discharge end. The vehicle, also includes a paver-loading conveyor that is
mounted on the turret.
The paver-loading conveyor has an inlet end extending into the discharge
opening on the rear
side of the surge bin, and an outlet end, and it is adapted to move asphalt
from the inlet end to the
outlet end. In a preferred embodiment of the invention, the material transfer
vehicle has a frame
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supported by at least four steerable wheels. In this embodiment of the
invention, three steering
modes are provided: (1) front wheel steering; (2) coordinated front and rear
wheel steering for
obtaining a shorter turning radius; and (3) coordinated front and rear wheel
steering for obtaining
sideways, or "crab" motion. The preferred embodiment also includes a forward-
mounted
operator station and a rear-view camera mounted on the underside of the paver-
loading
conveyor. The preferred embodiment also includes a transverse mixing auger in
the surge bin
having auger blades with varied pitch and/or diameter. The preferred
embodiment of the
invention also includes a paver-loading conveyor that is adapted pivot between
a lowered
position and a raised position that is about 25 above the horizontal.
In order to facilitate an understanding of the invention, the preferred
embodiments of the
invention are illustrated in the drawings, and a detailed description thereof
follows. It is not
intended, however, that the invention be limited to the particular embodiments
described or
illustrated herein. Various modifications and alternative embodiments such as
would ordinarily
occur to one skilled in the art to which the invention relates are also
contemplated and included
within the scope of the invention described and claimed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
The presently preferred embodiments of the invention are illustrated in the
accompanying
drawings, in which:
Figure I is a side view of a conventional material transfer vehicle in
association with an asphalt
delivery truck and an asphalt paving machine.
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Figure 2 is a side view of another conventional material transfer vehicle.
Figure 3 is a top view of the vehicle of Figure 2.
Figure 4 is a side view of a first embodiment of the invention showing the
paver-loading
conveyor in an elevated position.
Figure 5 is a top view of the embodiment of Figure 4 showing the paver-loading
conveyor in an
elevated position.
Figure 6 is a bottom view of the embodiment of Figures 4-5 showing the paver-
loading conveyor
in an elevated position.
Figure 7 is a front view of the embodiment of Figures 4-6 showing the paver-
loading conveyor in
an elevated position.
Figure 8 is a rear view of the embodiment of Figures 4-7 showing the paver-
loading conveyor in
an elevated position.
Figure 9 is a rear perspective view of the embodiment of Figures 4-8 showing
the paver-loading
conveyor in an elevated position.
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Figure 10 is a side view of the embodiment of Figures 4-9 showing the turret,
in a rotated
position.
Figure 11 is a rear perspective view of the embodiment of Figures 4-10 showing
the turret, in a
rotated position.
Figure 12 is a top view of the embodiment of Figures 4-11 showing the turret
in a rotated
position.
Figure 13 is a rear view of the embodiment of Figures 4-12 showing the turret
in a rotated
position.
Figure 14 is a side view of the embodiment of Figures 4-13 showing the paver-
loading conveyor
in a lowered position and the truck-unloading conveyor in a raised or travel
position.
Figure 15 is a top view of the embodiment of Figures 4-14 showing the paver-
loading conveyor
in a lowered position and the truck-unloading conveyor in a raised or travel
position.
Figure 16 is a bottom view of the embodiment of Figures 4-15 showing the paver-
loading
conveyor in a lowered position and the truck-unloading conveyor in a raised or
travel position.
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Figure 17 is a rear perspective view of the embodiment of Figures 4-16 showing
the paver-
loading conveyor in a lowered position and the truck-unloading conveyor in a
raised or travel
position.
Figure 18 is a partial sectional view through the surge bin of the embodiment
of Figures 4-17,
taken through line 18-18 of Figure 5, showing a preferred embodiment of the
transverse mixing
auger in the surge bin.
Figure 19 is a partial sectional view through a surge bin similar to that of
Figure 18, showing an
alternative embodiment of the transverse mixing auger in the surge bin.
Figure 20 is a schematic illustration of the hydraulic circuit for the
steering system of the
embodiment of Figures 4-18.
Figure 21 is a.schematic illustration of the electrical switching for the rear
steering components
of the embodiment of Figures 4-18 and 20.
Figure 22 is a perspective view of a portion of the components of the rear
steering subsystem of
the embodiment of Figures 4-18 and 20-21.
Figure 23 is a side view of a second embodiment of the invention showing the
paver-loading
conveyor in an elevated position.
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Figure 24 is a front perspective view of the embodiment of Figure 23 showing
the paver-loading
conveyor in an elevated position.
Figure 25 is a rear perspective view of the embodiment of Figures 23-24
showing the paver-
loading conveyor in an elevated position.
Figure 26 is a top view of the embodiment of Figures 23-25 showing the turret
in a rotated
position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Figure 1 shows self-propelled material transfer vehicle 10 which is described
in U.S. Patents No.
4,818,139, No. 5,015,120 and No. 5,035,534 in association with asphalt paving
machine 12 and
conventional delivery truck 16. Paving machine 12 includes hopper 14 which has
been
expanded by providing front wall 14a and side walls 14b of increased height.
Paving machine
12 also includes vibratory screed 15 and conventional conveyor system
comprising
longitudinally disposed conveyors 19a and transversely disposed screw auger
19b for delivering
the asphalt from hopper 14 to a position just in advance of screed 15 where it
is discharged onto
the surface to be paved. Conventional delivery truck 16 includes a pivotally
mounted bed 17
with a tailgate 18, and is adapted to deliver asphalt from a remote source to
material transport
vehicle 10.
Vehicle 10 includes frame 20 that is supported on the roadway surface by first
wheel set 21 and
second wheel set 22. Each of the wheel sets is driven by a hydraulic motor
(not shown) that is
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supplied with fluid under pressure by one or more hydraulic pumps (also not
shown). An engine
(also not shown) provides the motive force for the hydraulic pumps. Vehicle 10
includes surge
bin 23 that is mounted on frame 20 and includes transverse auger 24 that is
employed to mix the
asphalt in the surge bin in order to minimize segregation or separation of the
aggregate portion of
the asphalt by size. Vehicle 10 also includes truck-receiving hopper 25 and
truck-unloading
conveyor 26 for receiving asphalt from delivery truck 16 and conveying it to
the surge bin.
Hopper 25 is generally of the same width as truck bed 17 and is adjustable in
length so that the
contents of truck 16 can be easily and quickly emptied into the hopper.
Conveyor 26 is of the
drag-slat type and is adapted to quickly convey an entire truckload of asphalt
into surge bin 23.
Drag-slat type discharge conveyor 28 is located along the sloped side of surge
bin 23 opposite
truck-unloading conveyor 26 and is adapted to convey asphalt out of the surge
bin to chute 30
which is associated with paver-loading conveyor 32. Asphalt conveyed out of
the surge bin by
conveyor 28 falls through chute 30 and onto paver-loading conveyor 32. Paver-
loading
conveyor 32 is of the belt-type and is mounted for vertical pivotal movement
about pivot 34 as
raised and lowered by hydraulic lift cylinder 36. Conveyor 32 is also adapted
for side-to-side
movement about a vertical axis (not shown) that extends through hopper 30 by
operation of
another hydraulic cylinder (also not shown). Vehicle 10 is operated by an
operator located at
operator station 38.
A modified version of vehicle 10 is illustrated in Figures 2 and 3. As shown
therein, vehicle 40
includes frame 42 that is supported on the roadway surface by first wheel set
44 and second
wheel set 46. Each wheel of a wheel set is connected to an axle that is driven
by a hydraulic
motor (not shown) which is supplied with fluid under pressure by one or more
hydraulic pumps
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(also not shown). An engine (located behind grate 48) provides the motive
force for the
hydraulic pumps. Vehicle 40 includes surge bin 50 that is mounted on the frame
and includes
transverse auger 52 that is employed to mix the asphalt in the surge bin in
order to minimize
segregation or separation of the aggregate portion of the asphalt by size.
Vehicle 40 also
~
includes truck-receiving hopper 54 and truck-unloading conveyor 56 for
receiving asphalt from a
delivery truck such as truck 16 and conveying it to the surge bin. Hopper 54
is generally of the
same width as truck bed 17 and is adjustable in length so that the contents of
truck 16 can be
easily and quickiy emptied into the hopper. Conveyor 56 is of the drag-slat
type and is adapted
to quickly convey an entire truckload of asphalt into surge bin 50. Another
drag-slat type
discharge conveyor (not shown, but similar to conveyor 28 of vehicle 10) is
located along the
sloped side of surge bin 50 opposite truck-unloading conveyor 56 and is
adapted to convey
asphalt out of the surge bin to chute 58 which is associated with paver-
loading conveyor 60.
Asphalt conveyed out of the surge bin by the surge bin conveyor falls through
chute 58 and onto
paver-loading conveyor 60. Paver-loading conveyor 60 is of the belt-type and
is mounted for
vertical pivotal movement as raised and lowered by hydraulic lift cylinder 62.
Conveyor 60 is
also adapted for side-to-side movement about a vertical axis by operation of
another hydraulic
cylinder (also not shown). Vehicle 40 is operated by an operator located at
operator station 64.
A first embodiment of the invention is illustrated in Figures 4-18 and 20-22.
As shown in
Figures 4-17, self-propelled material transport vehicle 100 includes frame 102
having a front end
at 104 and a rear end at 106. Vehicle 100 includes a vehicle drive system
which is operatively
attached to frame 102 and adapted to drive the vehicle along a roadway
surface. As shown in
Figures 4-17, the vehicle drive system includes a front wheel set comprised of
left front wheel
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108 and right front wheel 109 and a rear wheel set comprised of left rear
wheel 110 and right
rear wheel 111. Preferably, as illustrated in the drawings, each wheel set is
comprised of a pair
of wheels with pneumatic tires; however, other wheel sets such as are known to
those having
ordinary skill in the art to which the invention relates may alterriatively be
used. Each wheel of a
wheel set is connected to an axle that is driven by a hydraulic motor (not
shown) which is
supplied with fluid under pressure by one or more hydraulic pumps (also not
shown). This
hydrostatic drive system is similar to the hydrostatic drive systems of
vehicles 10 and 40. An
engine (located in compartment 112) provides the motive force for the
hydraulic pumps. In this
embodiment of the invention (as described in more detail hereinafter), three
steering modes are
provided: (a) front wheel steering where front wheels 108 and 109 are
steerable in the manner of
an automobile and rear wheels 110 and 111 are set to roll in a line that is
parallel to longitudinal
frame axis 114 of the vehicle; (b) coordinated front and rear wheel steering
to pivot the vehicle
such as for example, by turning the front wheels to the right and
simultaneously turning the rear
wheels to the left to reduce the turning radius of the vehicle; and (c)
coordinated front and rear
wheel steering to move the vehicle in a non-pivoting manner, i.e. "crabwise",
by turning both the
front and the rear wheels in the same direction to move the vehicle along a
line that is not
parallel to frame axis 114.
It is also preferred that the hydrostatic drive system of vehicle 100 permit
differential fluid flow
between the front and rear drive subsystems, and that it can be set or
"locked" to provide equal
flow to the front and rear drive subsystems to improve vehicle stability on
loose or muddy
terrain. Such a vehicle drive system may include a valve arrangement in the
hydraulic fluid lines
to the hydraulic motors to permit flow of hydraulic fluid at the same rate to
the front and rear
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hydraulic motors or to permit differential flow of hydraulic fluid (i.e. at a
different rate) to the
front and rear hydraulic motors, as selected by the operator.
The preferred embodiment of vehicle 100 also includes truck-unloading conveyor
116 having
inlet end 118 and outlet end 120. Truck receiving hopper 122 is mounted on the
inlet end of
truck-uriloading conveyor for receiving asphalt from a delivery truck such as
truck 16. Hopper
122 is generally of the same width as truck bed 17 and is adjustable in length
so that the contents
of a delivery truck can be easily and quickly emptied into the hopper.
Conveyor 116 is
preferably of the drag-slat type and is adapted to quickly convey an entire
truckload of asphalt
from the inlet end to the outlet end and into surge bin 124. Surge bin 124 is
adapted to contain a
quantity of asphalt and has a front side 126 and a rear side 128. Rear side
128 of surge bin 124
has a discharge opening to receive the inlet end of paver-loading conveyor
130.
Surge bin 124 and paver-loading conveyor 130 are mounted on turret 132 which
is rotatably
mounted on frame 102 so as to rotate about turret axis 134. In the embodiment
of the invention
illustrated in Figures 4-17, surge bin 124, engine compartment 112 and paver-
loading conveyor
130 are all mounted on rotatable turret 132 (best shown in Figure 4). In this
embodiment of the
invention, turret 132 is rotated to the left and right of frame axis 114 by
the action of a pair of
actuators (one of which, hydraulic cylinder 136, is shown in Figure 4) which
are connected
between rear side 128 of surge bin 124 and a bracket (not shown) on the frame
adjacent to the
rear wheel set: Preferably, by coordinating the extension and retraction of
these linear actuators
(including cylinder 136), the turret may be rotated from an angle 0 of about
45 to the left of
CA 02591166 2007-06-15
frame axis 114 (best shown in Figure 12) through an angle of about 45 to the
right of frame axis
114. Rotation of turret 132 to the left side of axis 114 is illustrated in
Figures 10-13.
Extending from the discharge opening at the bottom of rear side 128 of
preferred surge bin 124 is
paver-loading conveyor 130. Paver-loading conveyor 130 has an inlet end 138
(shown in Figure
18) and an outlet end 140. Paver-loading conveyor 130 is mounted on turret
132, either directly
or indirectly (by attachment to the surge bin). Paver-loading conveyor 130 is
preferably of the
drag-slat type, and is adapted to transport asphalt from inlet end 138 in
surge bin 124 to outlet
end 140 and into the hopper of a paving machine (such as hopper 14 of paving
machine 12,
shown in Figure 1). Preferably, the inlet end of paver-loading conveyor 130 is
pivotally attached
to the turret (or to the surge bin), so that paver-loading conveyor 130 may be
pivoted between a
lowered position that is preferably about 12 above the horizontal (shown in
Figures 14-17) and
a raised position that is about 25 above the horizontal. It is also preferred
that the paver-loading
conveyor be pivoted between the lowered position and the raised position by a
pair of actuators
such as hydraulic cylinders 142 and 144 that are connected between rear side
128 of the surge
bin and the paver-loading conveyor. Figures 14-17 also show truck-unloading
conveyor 116 in a
raised travel position, which is accomplished by means known to those having
ordinary skill in
the art to which the invention relates.
As shown in Figures 5 and 18, a transverse mixing auger is mounted in the
lower portion of
preferred surge bin 124 between left outside sidewall 146 and right outside
sidewall 148.
Equidistant between the left outside sidewall arid the right outside sidewall
is a centerline (not
shown, but which is coplanar with paver-loader conveyor axis 150, shown in
Figure 5). The
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transverse mixing auger includes a plurality of auger blades mounted on shaft
152 for rotation
about transverse axis 154. The transverse mixing auger includes left-side set
156 of auger
blades, which is located between the surge bin centerline and left outside
sidewall 146, and right-
side set 158 of auger blades, which is located between the centerlineand right
outside sidewall
148. Preferably, as shown in Figure 18, inlet end 138 of paver-loading
conveyor 130 is located
between the left-side set of auger blades and the right-side set of auger
blades.
It is also preferred that auger blade 160 in left-side set 156 that is located
nearest the centerline
has a diameter greater than that of auger blade 162 in the left-side set that
is nearest left outside
sidewall 146. Preferably, as shown in Figure 18, except for auger blade 162
that is located
adjacent to left outside sidewall 146, the diameter of each auger blade in
left-side set 156 is
greater than the diameter of the adjacent auger blade in the left-side set
that is located nearer to
left outside sidewall 146. It is also preferred that auger blade 164 in right-
side set 158 that is
located nearest the centerline has a diameter greater than that of auger blade
166 in the right-side
set that is nearest right outside sidewall 148. Furthermore, it is also
preferred that except for
auger blade 166 that is located adjacent to right outside sidewall 148, the
diameter of each auger
blade in right-side set 158 is greater than the diameter of the adjacent auger
blade in the right-
side set that is located nearer to right outside sidewall 148. By providing
the preferred transverse
mixing auger with auger blades having a varied diameter across the surge bin,
segregation and
separation of aggregate material iri the asphalt mix is minimized.
Figure 19 illustrates an alternative transverse mixing auger that is mounted
in the lower portion
of surge bin 224, which is interchangeable with surge bin 124 on vehicle 100.
This alternative
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mixing auger is mounted between left outside sidewall 246 and right outside
sidewall 248 of
surge bin 224. Equidistant between the left outside sidewall and the right
outside sidewall is a
centerline (not shown). This mixing auger includes a plurality of auger blades
mounted on a
shaft for rotation about transverse axis 254. This alternative mixing auger
includes left-side set
256 of auger blades, which is located between the surge bin centerline and
left outside sidewall
246, and right-side set 258 of auger blades, which is located between the
centerline and right
outside sidewall 248. Preferably, as shown in Figure 19, the inlet end of
paver-loading conveyor
230 (which is essentially identical to conveyor 130) is located between the
left-side set of auger
blades and the right-side set of auger blades. As can be seen by comparing
Figure 19 and Figure
18, the auger blades of the alternative mixing auger having a varied diameter
across the surge bin
in the same way that the diameter of the auger blades varies across surge bin
124 of Figure 18.
However, it is also preferred in this alternative embodiment that the pitch
(indicated at 260)
between the auger blade in the left-side set that is located nearest the
centerline and the adjacent
auger blade in the left-side set is greater than the pitch (indicated at 262)
between the auger blade
in the left-side set that is located nearest the left outside sidewall and the
adjacent auger blade in
the left-side set. In fact, it is especially preferred that except for the
auger blade located adjacent
to the left outside sidewall, the pitch between each auger blade in the left-
side set and the
adjacent auger blade that is nearer the centerline is greater than the pitch
between such auger
blade and the adjacent auger blade nearer the left outside sidewall.
Similarly, it is preferred that
the pitch between the auger blade in the right-side set that is located
nearest the centerline and
the adjacent auger blade in the right-side set is greater than the pitch
between the auger blade in
the right-side set that is located nearest the right outside sidewall and the
adjacent auger blade in
the right-side set. It is also preferred that except for the auger blade
located adjacent to the right
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outside sidewall, the pitch between each auger blade in the right-side set and
the adjacent auger
blade that is nearer the centerline is greater than the pitch between such
auger blade and the
adjacent auger blade nearer the right outside sidewall. This alternative
mixing auger has auger
blades with varied diameter and pitch across the surge bin, which would also
serve to minimize
segregation and separation of aggregate materials of various particle sizes.
Referring again to Figures 4-17, preferred vehicle 100 also includes a forward-
mounted operator
station, (shown schematically at 168) which is mounted above truck-unloading
conveyor 116 on
supports 170 and 172 that are attached to frame 102. Preferably, operator
station 168 is located
in front of the front wheel set. Since the operator's station of this
embodiment of the invention is
located on the front portion of the vehicle, it is also preferred that a rear-
view camera 174 be
provided which is mounted on the underside of paver-loading conveyor 130, and
that the
operator's station include a monitor (not shown) for displaying an image from
camera 174.
Preferably, steering of the front wheel set is operated by a conventional
steering wheel (not
shown) and steering for the rear wheel set is operated by a joystick that is
located on a control
console (not shown) in operator's station 168. The preferred joystick for
steering the rear wheel
set has positions for steering left, steering right and centering the rear
wheel set (so that the
wheels of this wheel set are parallel to frame axis 114). By turning the
steering wheel to the left
or right and leaving the joystick in the -neutral (or centered) position, the
vehicle can be
maneuvered like a conventional automobile. By turning the steering wheel to
the left and
shifting the joystick to the right (or by turning the steering,wheel to the
right and shifting the
joystick to the left), the vehicle will steer in the direction the steering
wheel is turned but with a
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CA 02591166 2007-06-15
smaller turning radius than if the rear wheels remain centered. By turning the
steering wheel to
the left and shifting the joystick to the left (or by turning the steering
wheel to the right and
shifting the joystick to the right), the vehicle will move in a"crab-wise"
manner in a direction
that is oblique to the frame axis.
Referring now to Figure 20, the hydraulic circuit for the preferred steering
system of vehicle 100
is illustrated. As shown therein, this circuit includes a conventional
steering unit 176 which
controls the flow of fluid to left front steering cylinder 178 and right front
steering cylinder 180.
A conventional hydraulic solenoid valve 182 controls the flow of fluid to left
rear steering
cylinder 184 and right rear steering cylinder 186. A position sensor valve 188
(also shown in
Figure 22) such as is sold under the trademark MICROTORK by Microtork-
Rotovalve of
Warren, New Jersey, is linked by linkage 190 to the steering yoke connection
point for the rear
wheel set in order to sense the angular position of the rear wheel set with
respect to the frame.
Referring now to Figures 20 and 21, it can be seen that energizing switch 192
(by shifting the
rear steering joystick to the left) allows four-way, three-position
directional solenoid valve 182 to
direct flow to the piston side of cylinder 184 and to the rod side of cylinder
186 to steer the rear
wheel set to the left, while energizing switch 194 (by shifting the rear
steering joystick to the
right) allows four-way, three-position directional solenoid valve 182 to
direct flow to the piston
side of cylinder 186 and the rod side of cylinder 184 to steer the rear wheel.
set to the right.
When rear steering centering switch 196, which is preferably operated by a
button on the
joystick, is energized, two-way poppet solenoid valve 193 directs flow through
position sensor
valve 188 to position hold valve 198, which causes left rear steering cylinder
184 and right rear
steering cylinder 186 to center the rear wheel set so that the rear wheels are
aligned with the
CA 02591166 2007-06-15
frame axis. If the joystick is shifted either to the left or the right without
engaging rear steering
centering switch 196, position hold valve 198 will maintain the left-steered
or right-steered
position of the rear wheel set until the joystick is shifted in the other
direction or centering switch
196 is energized.
Figures 23-26 illustrate a second embodiment of the invention. As shown
therein, self-propelled
material transport vehicle 200 includes frame 202 having a front end at 204
and a rear end at
206. Vehicle 200 includes a vehicle drive system which is operatively attached
to frame 202 and
is adapted to drive the vehicle along a roadway surface. This vehicle drive
system includes a
front wheel set comprised of left front whee1208 and right front whee1209 and
a rear wheel set
comprised of left rear whee1210 and right rear whee1211. Each wheel of a wheel
set is
connected to an axle that is driven by a hydraulic motor (not shown) which is
supplied with fluid
under pressure by one or more hydraulic pumps (also not shown). This
hydrostatic drive system
is similar to the hydrostatic drive systems of vehicles 10, 40 and 100. An
engine (located in
compartment 212) provides the motive force for the hydraulic pumps. In this
embodiment of the
invention, it is preferred that the same steering modes be provided as are
described herein in
connection with the description of vehicle 100.
The preferred embodiment of vehicle 200 also includes truck-unloading conveyor
216 having
inlet end 218 and outlet end 220. Truck receiving hopper 222 is mounted on the
inlet end of
truck-unloading conveyor for receiving asphalt from a delivery truck such as
truck 16. Hopper
222 is generally of the same width as truck bed 17 and is adjustable in length
so that the contents
of a delivery truck can be easily and quickly emptied into the hopper.
Conveyor 216 is
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CA 02591166 2007-06-15
preferably of the drag-slat type and is adapted to quickly convey an entire
truckload of asphalt =
from the inlet end to the outlet end and into surge bin 223. Surge bin 223 is
adapted to contain a
quantity of asphalt and has a front side 226 and a rear side 228. Rear side
228 of surge bin 223
has a discharge opening to receive the inlet end of paver-loading conveyor
229. Surge bin 223
and paver-loading conveyor 229 are mounted on turret 232 which is rotatably
mounted on frame
202 so as to rotate about turret axis 234. In the embodiment of the invention
illustrated in
Figures 23-26, engine compartment 212 is mounted on frame 202, instead of on
the turret.
A transverse mixing auger (not shown, but which may be similar to those
illustrated in Figures
18 and 19 in connection with the description of vehicle 100) is mounted in the
lower portion of
preferred surge bin 223 between left outside sidewal1245 and right outside
sidewall 247.
Equidistant between the left outside sidewall and the right outside sidewall
is a centerline (not
shown, but which is coplanar with paver-loader conveyor axis 250, shown in
Figure 26). The
transverse mixing auger includes a plurality of auger blades mounted on a
shaft (not shown) for
rotation about transverse axis 254. The transverse mixing auger may include a
left-side set of
auger blades (not shown), which is located between the surge bin centerline
and left outside
sidewall 245, and a right-side set of auger blades (also not shown), which is
located between the
centerline and right outside sidewall 247.
Extending from the discharge opening at the bottom of rear side 228 of
preferred surge bin 223 is
paver-loading conveyor 229. Paver-loading conveyor 229 has an inlet end
(similar to inlet end
138 of conveyor 130 of vehicle 100), and an outlet end 240. The paver-loading
conveyor is
mounted on the turret, either directly or indirectly (by being attached to the
surge bin).
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Preferably, the inlet end of paver-loading conveyor 229 is pivotally attached
to the turret (or to
the surge bin) so as to be located between the left-side set of auger blades
and the right-side set
of auger blades (similar to the location of inlet end 138 of paver-loading
conveyor 130 which is
illustrated in Figure 18). Paver-loading conveyor 229 is preferably of the
drag-slat type, and is
adapted to transport asphalt from its inlet end in surge bin 223 to outlet end
240 and into the
hopper of a paving machine (such as hopper 14 of paving machine 12, shown in
Figure 1).
Preferably, paver-loading conveyor 229 is adapted to be pivoted between a
lowered position that
is preferably about 12 above the horizontal (not shown, but similar to the
lowered position of
paver-loading conveyor 130 of vehicle that is shown in Figures 14-17) and a
raised position that
is about 25 above the horizontal. It is also preferred that the paver-loader
conveyor be pivoted
between the lowered position and the raised position by an actuator comprising
hydraulic
cylinder 242 that is connected between rear side 228 of the surge bin and the
paver-loader
conveyor.
In this embodiment of the invention, turret 232 is rotated to the left and
right of frame axis 214
by the action of a pair of actuators (one of which, hydraulic cylinder 236, is
shown in Figures 23
and 25) which are connected between rear side 228 of surge bin 223 and a
bracket (not shown)
on the frame adjacent to the rear wheel set. Preferably, by coordinating the
extension and
retraction of these linear actuators (including cylinder 236), the turret may
be rotated from an
angle 0 of about 45 to the left of frame axis 214 (shown in Figure 26)
through an angle of about
45 to the right of frame axis 214.
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CA 02591166 2007-06-15
Vehicle 200 also includes a forward-mounted operator station, (shown
schematically at 268)
which is mounted above truck-unloading conveyor 216 on supports (including
stairway support
270) that are attached to frame 202. Preferably, operator station 268 is
located in front of the
front wheel set. Since the operator's station of this embodiment of the
invention is located on the
front portion of the vehicle, it is also preferred that a rear-view camera 274
be provided which is
mounted on the underside of paver-loading conveyor 229, and that the
operator's station include
a monitor (not shown) for displaying an image from camera 274.
Although this description contains many specifics, these should not be
construed as limiting the
scope of the invention but as merely providing illustrations of some of the
presently preferred
embodiments thereof, as well as the best mode contemplated by the inventors of
carrying out the
invention. The invention, as described herein, is susceptible to various
modifications and
adaptations, as would be understood by those having ordinary skill in the art
to which the
invention relates, and the same are intended to be comprehended within the
meaning and range
of equivalents of the appended claims.
What is claimed is:
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