Extensible screed and auger assembly for a road paving machine

Abstract

The invention relates to a paving machine, and more particularly to an extensible screed and auger assembly for use thereon. The paver, which is self-propelled, includes a frame, a tiltable hopper having a discharge opening, a generally vertical center strike-off assembly connected to the frame and positioned rearwardly of the discharge opening, a pair of laterally extensible strike-off plates connected to the center assembly and a pair of rotatable augers positioned between the discharge opening and the strike-off plates. The augers are mounted on the side strike-off plates and coextend therewith relative to the center assembly.

Description

BACKGROUND OF THE INVENTION

The subject matter of the present invention relates to machines for spreading paving materials such as asphalt or the like to construct roadways, parking lots, driveways, etc. They are normally self-propelled and include a hopper having a discharge opening and a screed positioned rearwardly of the discharge opening and designed to level and smooth the paving material after it is deposited on the surface to be paved. In many of the prior art machines, the screed is extensible laterally in order that the width of the strip of material to be deposited may be varied. Furthermore, the machine will often include an auger or the like to assist in distributing the material laterally before it is leveled and compacted by the screed.

There are certain disadvantages and problems, however, which become apparent when machines including an extensible screed are used. Since the hopper discharge opening is normally no wider than the narrowest strip which can be paved, when the screed is extended it is difficult to provide a sufficient supply of paving material at the ends thereof. Although providing an auger directly behind the discharge opening will assist somewhat in evenly distributing the material, when the screed is fully extended the distances between the side wings and the ends of the auger are so great that an insufficient amount of material will be provided at the outermost points of the screed. Such a deficiency in the amount of paving material at the ends of the screed results in a paved surface which tapers off laterally.

To counteract these problems it is necessary to pave at a slower rate thereby affording more time for the auger to force the material in front of the extended portions of the screed. Often costly and time consuming hand shoveling is also required to assist in maintaining a uniform level of material in front of the extended screed. Aside from reducing the rate at which paving can be accomplished, another drawback to these solutions lies in the fact that the asphalt is much more likely to cool while it is being shoveled thereby resulting in a surface of diminished quality. Furthermore, idling the machine while shoveling causes an unnecessary consumption of fuel. Also, the necessity for maintaining a large amount of material in front of the screed at all times renders it difficult to end a strip of paving along a straight line of constant thickness. If the amount of material in front of the screed is permitted to diminish as the strip is completed, the outer ends of the extended screed will not receive sufficient material to assure even paving. On the other hand, if the area in front of the screed is filled with paving material until the machine is stopped, it will be necessary to manually shovel the paving material back into the hopper.

To assure an even supply of paving material to the screed in situations where strips of varying widths are to be paved, the prior art machines have been made unduly large and complicated thereby rendering them expensive to purchase and maintain. Also, for paving requirements of smaller scope, the larger machines do not operate at peak efficiency and result in unnecessary consumption of fuel and manpower. Difficulty of transportation is also a factor.

OBJECTS OF THE INVENTION

It is, therefore, an object of this invention to provide a paving machine wherein the paving material is distributed evenly in front of the screed over a varying range of paving widths.

A further object of this invention is to provide a paving machine wherein manual attachment of screed extensions, as by bolting, is eliminated.

Another object of this invention is to provide a paving machine including an extensible screed wherein manual shoveling to assure even material supply to the screed is eliminated.

A further object of this invention is to provide a paving machine which is able to lay strips of paving of varying widths rapidly and efficiently without undue consumption of fuel or a large crew as necessitated by inherently slow gear mechanisms or manual bolt-on attachments for changing the effective screed width.

A further object of this invention is to provide a paving machine which is able to pave strips of constant thickness with a minimum of material in the screed area.

A still further object of this invention is to provide a paving machine capable of terminating a strip of pavement along a straight line of even thickness.

Yet another object of this invention is to provide a paving machine which is greatly maneuverable and able to pave irregularly shaped areas or strips of varying width without the necessity for stopping.

SUMMARY OF THE INVENTION

The invention is a screed and auger assembly comprising strike-off means including a first strike-off member and a second strike-off member for leveling and smoothing paving material which has been deposited on a surface to be paved, material conveying means mounted on the second member and positioned forwardly of the strike-off means, means connecting the second member to the first member for permitting lateral rectilinear movement of the second member and the conveying means relative to the first member and means for moving the second member and the conveying means linearly relative to the first member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of the invention;

FIG. 2 is a fragmentary perspective view of the left-hand screed and auger assembly of the machine illustrated in FIG. 1 viewed 45.degree. above the horizontal;

FIG. 3 is a fragmentary rear elevational view of that portion of the machine illustrated in FIG. 2;

FIG. 4 is a side elevational view of the machine of the preceeding figures with portions thereof broken away to illustrate the details of contruction;

FIG. 5 is a top plan view of the screed and auger assembly of the machine illustrated in the preceeding figures; and

FIG. 6 is a schematic of the hydraulic system for the machine illustrated in the preceeding figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring particularly to FIGS. 1 and 4, the paving machine of the present invention includes a frame 10, a hopper 12 supported thereby and a screed and auger assembly 14 connected to frame 10 by means of arms 16 and 18 pivotally attached thereto as at 20. The hopper is generally of two-piece construction including a rear portion 22 rigidly connected to or integral with frame 10 and a forward portion 24 having a bed 26 and side walls 28. The forward portion 24 is pivotally secured to frame 10 by means of hinge 30 and raised or lowered through the action of hydraulic cylinders 32. This construction permits the hopper bed 26 to be raised or lowered to adjust to varying dump truck heights as well as permitting the hopper 12 to be completely emptied without the necessity for manual shoveling.

A pair of hopper doors 34 and 36 are pivotally secured to rear portion 22 of hopper 12 by means of hinges 38 and opened or closed by hydraulic cylinders 40 and 42, the latter being pivotally attached to brackets 44 and 46 on doors 34 and 36 and brackets 48 and 50 on hopper rear wall 51. When the doors 34 and 36 are closed, the lower edges 52 abut the downwardly inclined fender 54 of hopper 12 thereby preventing the paving material from flowing from hopper 12 into the screed area 56.

The paving machine is propelled by means of endless track 58 which is driven by hydraulic motors 190 and 192 powered by hydraulic pump 60 which in turn is driven by an internal combustion engine 62. Rollers such as 64 are mounted on the forward end of frame 10 and adapted to push a dump truck or the like as paving material is being dumped into hopper 12. A series of lever operated valves 66 control the flow of hydraulic fluid from pump 60 to the various hydraulic rams and motors which control the operation of the machine.

A description of the screed and auger assembly 14 will now be undertaken with particular reference to FIGS. 2, 3, 4 and 5.

The screed and auger assembly 14 comprises generally a center strike-off assembly 68, a pair of side strike-off plates 70 and 72 slidably mounted on center member 68 and a pair of rotatable augers 73 and 75 mounted on side strike-off plates 70 and 72, respectively. The center strike-off assembly 68 is preferably of two-piece construction including a left half 74 and a right half 76 (FIG. 2) and pivotally joined at their lower inside corners 77. By means of threaded adjusting rods 78 and 80 which are secured to brackets 82 and 84 on left and right halves 74 and 76 of center strike-off assembly 68 and threaded rod coupling 86, the left and right portions 74 and 76 may be rotated about a central horizontal axis to adjust the angle which the two halves 74 and 76 of center strike-off member 68 make with the ground. Lever 88 serves to rotate the coupling 88 relative to rods 78 and 80. The left and right halves 74 and 76 of strike-off member 68 include vertical portions 90 and 92 and generally horizontal portions 94 and 96 integral therewith.

The right and left halves 74 and 76 of center member 68 are connected to arms 16 and 18 by means of downwardly extending arms 100 and 102 which are welded or otherwise rigidly connected to connecting arms 16 and 18 as well as bushings 104 which are pivotally connected to portions 94 and 96. In this manner, the center strike-off assembly 68 is pivotable about a horizontal axis. Threaded rods 106 and 108 are rotatably connected to the halves 74 and 76 of strike-off assembly 68 as at 110 and 112 and pass through nuts 114 and 116 which are mounted on connecting arms 16 and 18. By rotating cranks 118 and 120 the rear portion of horizontal portions 94 and 96 are moved relative to arms 100 and 102 thereby causing rotation about the axis of bushings 104.

A pair of platforms 122 and 124 are welded or otherwise secured to center strike-off assembly 68 to support the machine operator or operators. A hydraulic ram 125, which is mounted to hopper rear wall 51 by means of bracket 127, serves to raise and lower the screed and auger assembly 14.

The side strike-off plates 70 and 72 are provided with brackets 126 and 128 and side wings 130 and 132, the latter serving to contain within the screed area 56 the paving material discharged from the hopper 12. Augers 73 and 75 are rotatably mounted between bracket 126 and bearing 134 on side wing 130 and bracket 128 and bearing 136 on side wing 132, respectively. Reversible hydraulic motors 138 and 140 serve to rotate the augers 73 and 75 in either clockwise or counter-clockwise directions depending on the position of the appropriate control valves 66. Since the augers 73 and 75 are mounted low within the screed area 56, only a minimum amount of paving material within area 56 is necessary to assure even distribution.

A pair of connecting tubes 142 and 144 mounted on side wing 130 pass through concentric tubular members 146 and 148 and are rigidly secured to a free plate 150. Similarly, a pair of connecting tubes 152 and 154 are rigidly secured to side wing 132 and free plate 156 and pass through concentric tubular members 158 and 160. Tubular members 146 and 148 are mounted to the left half 74 of strike-off assembly 68 and bracket 162. In similar fashion, tubular members 158 and 160 are mounted on the right half 76 of assembly 68 and bracket 164. Bolts 166 and 168 pass through slots 170 (FIG. 3) in members 74 and 76 and are threadedly secured to side plates 70 and 72 by means of lock nuts 172 and 174. Appropriate washers or the like 176 may be provided on the rear sides of members 74 and 76.

The cylinder 178 of hydraulic ram 184 is mounted on bracket 172 and the piston rod 180 on free plate 150. A second hydraulic ram 182 is similarly mounted on bracket 164 and plate 156. By these means, the side strike-off plates 70 and 72 are slidably mounted on the center assembly 68 for lateral movement relative thereto. By proper actuation of the hydraulic rams 182 and 184, the side strike-off plates 70 and 72 may be extended or retracted to vary the width of the paved strip. Since the augers 73 and 75 are mounted on the side plates 70 and 72, they will be extended or retracted coextensibly therewith.

Referring now to FIG. 6, an appropriate hydraulic fluid is pumped from reservoir 186 through filter 188 to valves 66 by means of pump 60. By acutation of the appropriate valves 66, the machine is propelled and steered by motors 190 and 192, the hopper bed 26 raised and lowered by cylinders 32, the doors 34 and 36 opened and closed by cylinders 40 and 42, the side strike-off plates 70 and 74 extended and retracted by cylinders 184 and 182, respectively, the augers 73 and 75 rotated either clockwise or counter-clockwise by motors 138 and 140, respectively, and the screed and auger assembly 94 raised and lowered by cylinder 125. The return lines from the motors 138, 140, 190 and 192 as well as from the bank of valves 66 are connected to filter 194 and then to reservoir 186.

The machine operates as follows.

As the machine moves forward on tracks 58, asphalt or the like is dumped from hopper 12 through the discharge openings created by open doors 34 and 36 into the area 56 immediately forward of the center strike-off assembly 68 and side strike-off plates 70 and 72. The side plates 70 and 72 may be extended an appropriate distance depending on the width of paving desired. As the asphalt falls into screed area 56, it is conveyed outwardly by means of augers 73 and 75. Should an excessive amount of material accumulate in the area of the extended side plates 70 or 72, the augers 73 and 75 may be reversed.

The side strike-off plates 70 and 72, side wings 130 and 132 and augers 73 and 75 may be extended or retracted as units by supplying hydraulic fluid under pressure to either side of hydraulic rams 182 and 184. For example, should it be desired to extend side plate 70, fluid under pressure is introduced into the right side of ram 184 thereby moving piston rod 180, free plate 150, stabilizer tubes 142 and 144, side wing 130, side strike-off plate 70 and auger 73 to the left. As this occurs, the bolt 166 which is connected to strike-off plate 70 also moves to the left within slot 170. Since no adjustments or modifications need be made to extend or retract the side plates 70 and 72 and their respective augers 73 and 75, the width of paving material deposited may be varied without the necessity for stopping the machine.

For the sake of clarity in illustrating the invention, the details of the hydraulic system have been omitted with the exception of the schematic of FIG. 6.

While this invention has been described as having a preferred design, it will be understood that it is capable of further modification. This application is, therefore, intended to cover any variations, uses or adaptations of the invention following the general principles thereof and including such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and as may be applied to the essential features hereinbefore set forth and fall within the scope of this invention or the limits of the appended claims.

Claims

What is claimed is:

1. A machine for spreading paving material comprising:

a. material transport means for transporting a quantity of paving material over a surface to be paved,

b. said transport means including discharge means for depositing the paving material on the surface to be paved,

c. extensible strike-off means connected to said transport means and positioned rearwardly of said discharge means for leveling and smoothing the paving material as it is deposited on the surface to be paved,

d. said strike-off means including a laterally stationary first member and a second member connected to said first member for lateral movement relative thereto,

e. a rotatable auger mounted on and carried by said second member and positioned between said discharge means and said strike-off means, and

f. means for laterally extending and retracting said second member and said auger.

2. The machine of claim 1 and wherein:

a. said transport means includes a hopper, and

b. said discharge means is an opening in said hopper.

3. The machine in claim 1 and wherein said first and second members include respectively first and second vertical plates connected for slidable lateral movement relative to each other.

4. The machine of claim 3 and wherein said auger is mounted substantially directly in front of said vertical plates.

5. The machine of claim 1 and wherein said strike-off means further includes:

a. a laterally stationary third member and a fourth member connected to said third member for lateral movement relative thereto,

b. a second auger mounted on and carried by said fourth member.

6. The machine of claim 5 and including means for laterally extending and retracting said fourth member and said second auger.

7. The machine of claim 6 and including remotely controlled means for rotating said augers independently of each other.

8. A screed and auger assembly for paving machines comprising:

a. strike-off means for leveling and smoothing paving material which has been deposited on a surface to be paved,

b. said strike-off means including a first strike-off member and a second strike-off member,

c. material conveying means being mounted on said second member,

d. means connecting said second member to said first member for permitting lateral rectilinear movement of said second member and said conveying means relative to said first member,

e. said material conveying means being positioned forwardly of said strike-off means, and

f. means for moving said second member and said conveying means linearly relative to said first member.

9. The assembly of claim 8 and wherein said material conveying means is an auger.

10. The assembly of claim 9 and wherein:

a. said first strike-off member includes a substantially vertical plate, and

b. said second strike-off member includes a substantially vertical plate slidably mounted on said first member.

11. The assembly of claim 10 and wherein said means connecting said second member to said first member includes:

a. a hollow stabilizing member rigidly mounted to said first member, and

b. an elongated connecting member rigidly connected to said second member and slidably disposed within said hollow member.

12. The assembly of claim 11 and wherein said means for moving said second member and said conveying means includes:

a. a hydraulic ram, and

b. means connecting said ram between said first member and said connecting member to extend and retract said second member relative to said first member.

13. The assembly of claim 11 and wherein said means connecting said second member to said first member includes a bolt connected to one of said first or second members and passing through a slot in the other of said first or second members.

14. A screed and auger assembly for paving machines comprising:

a. strike-off means for leveling and smoothing paving material which has been deposited on the surface to be paved,

b. said strike-off means including a first strike-off member and a second strike-off member,

c. means connecting said second member to said first member for permitting lateral rectilinear movement of said second member relative to said first member between a fully retracted position and a fully extended position,

d. means for moving said second member laterally between said fully retracted and said fully extended positions, and

e. a rotatable auger mounted on and carried by said second member,

f. said auger being completely supported by said second member and positioned forwardly of said strike-off means.