Methods and apparatus for making an asphalt-aggregate pavement

Abstract: An apparatus and method for delivering asphalt-aggregate material from a plurality of supply trucks (16) to a finishing machine (12). In a preferred form of the invention the hopper (14) of the finishing machine (12) is modified to have a capacity substantially equal to the capacity of one of the supply trucks (16). The apparatus (10) is a self-propelled storage vehicle including a hopper (23) having a capacity substantially equal to the capacity of one of the supply trucks (16), a high capacity loading conveyor (33), and a high capacity unloading conveyor system (47). A transversely disposed screw auger (60) is provided for remixing the asphalt-aggregate material in the hopper (23) prior to its discharge to the finishing machine (12). In the first method of operation the storage vehicle (10) shuttles between the finishing machine (12) and a remote location of the supply trucks (16) and in the second method of operation the storage vehicle (10) travels in tandem with the finishing machine (12) as the paving operation is performed. The high capacity loading conveyor (33) can be equipped with an extendable trough (120) which has a pivotally attached trough floor (126) with front (132) and side plates (130). The extendable trough (120) provides a large area which facilitates discharge of paving material from frameless trailers and allows for the early departure of the supply trucks (16) from the conveyor (33). The final discharged paving material is gradually emptied from the extendable trough (120) into the conveyor (33) by hydraulic cylinders (146) which tilt the trough (120) to slide the material in the trough (120) into the infeed end of the conveyor (33).

Description: The present invention relates in general to methods of transferring material from a delivery truck to a self-propelled mobile apparatus and to an apparatus capable of receiving such material from a delivery truck. The invention is particularly, but not exclusively, applicable to making asphalt-aggregate roadway. The conventional method of laying an asphalt-aggregate roadway mat includes the use of a finishing machine and a number of delivery trucks to transport the asphalt-aggregate material from the asphalt plant to the job site. Finishing machines of the type hereunder consideration, sometimes called pavers, are well-known to those skilled in the art. Such a finishing machine has a so-called floating screed at its rear end, usually provided with some form of vibratory means, to form the asphalt mat. The finishing machine also includes a hopper at its front end for receiving the asphalt-aggregate material and suitable conveyor means, usually slat conveyors and screw augers, for delivering the material from the hopper to a position just in advance of the screed. A typical finishing machine has a hopper with a capacity of approximately 5 tons. A typical delivery truck, usually a dump truck, will have a capacity of approximately 20 tons. The technique for transferring the asphalt-aggregate material from the dump truck to the hopper of the finishing machine screed normally requires the truck driver to position his vehicle immediately in front of the finishing machine, the latter being provided with rollers which engage the rear tires of the truck. During the time that the material is being transferred from the dump truck to the hopper of the finishing machine, the latter is advancing along the subgrade as it forms the asphalt-aggregate mat and in doing so pushes the truck forwardly in tandem therewith. A number of problems arise when operating the finishing machine and the delivery trucks in the manner just described. Quite frequently, the hopper of the finishing machine will be nearly empty and thus ready to be refilled, but a loaded dump truck will not be available at the job site. The absence of a loaded delivery truck at the required time is most often due to traffic conditions which prevent the delivery trucks from arriving at the job site at the proper time intervals. When this occurs, the finishing machine must obviously stop and await the arrival of another delivery truck. As is known to those skilled in the art, when a finishing machine stops, even momentarily, the screed will tend to settle into the freshly laid mat. When the finishing machine then commences forward travel, the screed will tend to ride upwardly momentarily thus depositing an excessive amount of material. Consequently, the stopping of the finishing machine causes a depression and bump in the surface of the asphalt-aggregate mat resulting in an uneven pavement surface. Needless to say, it is desirable to produce the smoothest possible surface. It is often necessary to stop the finishing machine even though one or more loaded delivery trucks are available at the job site. This is so since quite often it is simply impossible for the truck drivers to remove the empty delivery truck from the front of the finishing machine and to maneuver a full delivery truck into a position in advance of the finishing machine before the finishing machine runs out of material. As illustrated in Table I (set forth below), as the paving rate of the paver, in tons per hour (TPH), increases the available truck exchange time decreases. As is known to those skilled in the art, at least 1.5 minutes are required to perform the truck exchanging operation. Therefore, it is apparent from the data in Table I that a finishing machine using the conventional supply methods cannot operate continuously at a rate greater than 200 TPH. In order to operate at a higher paving rate and still provide sufficient time to exchange trucks, the paver must stop each time the hopper's supply of paving material is exhausted. This situation is illustrated in Table II (set forth below), where the finishing machine, running discontinuously, can operate at a rate of 800-1200 TPH while still providing the necessary 1.5 minutes for the truck exchanging operation. However, this discontinuous operation of the finsihing machine results in an undesirable depression and hump on the pavement mat each time the finishing machine is stopped to perform the truck exchanging operation, as previously explained. In specification EP-A-0306152 the present applicant discloses using a self-propelled mobile apparatus for transferring asphalt-aggregate material from an independent delivery truck to an independent finishing machine. In operation, this apparatus is shuttled back and forth between delivery trucks and the finishing machine for intermittently delivering asphalt-aggregate material from the former to the latter, thereby solving the above-mentioned finishing machine stopping problem. In EP-A-0306152 which is part of the state of the art within the meaning of Article 54 paragraph 3 EPC there is disclosed an apparatus capable of receiving material from a delivery truck, which apparatus comprises inclined conveyor means mounted on chassis means, said conveyor means having an upper discharge portion and a lower inlet and a trough extending from said inlet to receive material from the delivery truck. In US-A-4765772 and DE-A-2628325 there is disclosed an apparatus capable of receiving material from a delivery truck, which apparatus comprises inclined conveyor means mounted on chassis means, said conveyor means having an upper discharge portion and a lower inlet. In order to allow a larger capacity trough to be used in the apparatus disclosed in EP-A-0306152 the present invention provides such a trough which is contractible towards the inlet for moving material into the inlet. Accordingly, there is provided an apparatus capable of receiving material from a delivery truck, which apparatus comprises inclined conveyor means mounted on chassis means, said conveyor means having a longitudinal axis, an upper discharge portion and a lower inlet and a trough which extends from said inlet to receive material from the delivery truck characterised in that said trough is retractible in the direction of said longitudinal axis towards said inlet whereby the trough volume is reduced for moving material into the inlet. The trough of the apparatus may comprise a floor which has two longitudinal edges and two side edges, the floor being pivotable at one longitudinal edge towards the inlet and provided at the other longitudinal edge with a transverse wall the trough also having two side walls extending between the side edges of the floor and the transverse wall. The apparatus may further comprise lifting means connected between the conveyor means and said trough to pivot said trough floor about said one longitudinal edge thereof where the lifting means preferably includes a hydraulic cylinder which may be connected between the conveyor means and a trough side wall. It is preferable that the transverse wall of the trough should have an upper portion projecting away from the inlet and a lip projecting approximately parallel to the trough floor. The apparatus may be provided with a trough having a first portion adjacent the inlet and comprising side walls and a bottom wall and when so provided the trough floor is pivotally connected to the bottom wall and each trough side wall is adjacent a respective first portion side wall and capable of slidable movement relative thereto. The apparatus may further comprise a gate means connected to the conveyor means for partially restricting flow of material from the trough into the conveyor means and when provided, the gate means may be adjustable. The apparatus may comprise a trough capable of holding material which defines an angle of repose such that when the material is received from the delivery truck the material must flow between the gate means and the angle of repose in order to reach the conveyor means. The invention also includes a method of transferring material from a delivery truck to a self propelled mobile apparatus which apparatus comprises an inclined conveyor means having a longitudinal axis, an upper discharge portion and a lower inlet, the method including providing a trough extending from said inlet to receive material from the delivery truck and being characterised by the steps of extending said trough in the direction of said longitudinal axis away from said inlet to expand the trough holding capacity, discharging material from the delivery truck into the trough and retracting the trough in the direction of said longitudinal axis towards said inlet whereby the trough volume is reduced, to feed material into said lower inlet of said conveyor means. The method may further comprise the step of reextending the trough after it is emptied of material. Preferably, the trough is extended by pivoting. Advantageously, the material may be discharged from a frameless trailer. The self-propelled mobile apparatus may comprise gate means projecting into the trough, in which case the method may further comprise the step of limiting the feed of material into the inlet of the conveyor means to material between the gate means and an angle of repose of material in the trough and preferably the trough has a floor and the floor of the trough is pivoted to at least the angle of repose. The method includes the case where the material is discharged from a frameless truck. In order that the invention may be well understood, a preferred embodiment of the invention, which is given by way of example only, will now be described, with reference to the accompanying drawings, in which: Figure 1 is a schematic side elevation showing a self-propelled storage vehicle disclosed in EP-A-0306 152, in association with a finishing machine and a delivery truck; Figure 2 is an enlarged side elevation of the same self-propelled storage vehicle; Figure 3 is a top plan view of the same self-propelled storage vehicle; Figure 4 is a section taken along the line 4-4 of Figure 2; Figure 5 is a section view taken along line 5-5 of Figure 2 with a portion of the discharge conveyor housing cut-away to show a portion of the discharge conveyor; Figure 6 is a diagrammatic view showing the hydrostatic drive system for the self-propelled storage vehicle and the associated hydraulic systems for the various conveyors; Figure 7 is an enlarged side elevation view of a self-propelled storage vehicle of Figures 1 to 6 equipped with a retractible trough to form the preferred embodiment of the present invention; Figure 8 is a detailed side elevation view of the retractible trough; Figure 9 is a front elevation view of the retractible trough; Figure 10 is a top plan view of the retractible trough; and Figure 11 is a side elevational view of the retractible trough shown in use with an adjustable gate feature. Referring to Figure 1, a self-propelled storage vehicle, is generally designated 10. The self-propelled storage vehicle which is shown in association with an independent finishing machine 12, and a delivery truck, 16, forms a self-propelled mobile apparatus for transferring asphalt-aggregate material from the truck 16 to the finishing machine 12. The delivery truck 16 is normally in the form of a dump truck having a pivotably mounted bed 17 with a tailgate 18. The truck 16 transfers the aggregate-asphalt material from a remote source to the storage vehicle 10 as will be explained below. The finishing machine may be supported either by endless tracks or by rubber tires and includes a hopper 14 and vibratory screed 15 which is of the floating type well known to those skilled in the art. The finishing machine also includes a conventional conveyor system consisting of longitudinally disposed conveyors 19a (shown in broken lines) and transversely disposed screw augers 19b for delivering the asphalt-aggregate material from the hopper 14 to a position just in advance of the screed 15 where it is discharged onto the subgrade. The hopper of a conventional finishing machine is open at its front and has low side walls to receive the material from the dump truck. By using the self propelled vehicle 10 described in specification EP-A-0306152, the hopper of the finishing machine may be modified so that its capacity is expanded from the standard 5 tons to 12 tons, or even as high as 20 tons. This modification can be made by providing a wall 14a at the front of the otherwise conventional hopper and by increasing the height of the side walls 14b, as shown in Figure 1. Of course, the standard supply truck 16 cannot deliver the aggregate-asphalt material to the modified hopper 14 because the truck's bed 17 discharges at an elevation well below the height of wall 14a. However, the storage vehicle 10 is able to discharge the aggregate-asphalt material into the upwardly expanded hopper 14 because the discharge conveyor can swing vertically to an adequate height, as will hereinafter be explained. Referring more particularly to Figures 2, 3 and 6, the self-propelled storage vehicle 10 includes a chassis 18 that is supported on the roadway surface by first and second wheel sets 20 and 21, respectively. It will be understood that alternative roadway engaging means, such as endless tracks, could be used in place of the wheel sets 20 and 21. As shown in Figure 6, the hydrostatic drive system for the self-propelled storage vehicle 10 consists of individual hydraulic motors 101-109 that are supplied with fluid pressure from the hydraulic pumps 110-114. (It should be noted that the intake and exhaust lines for the hydraulic motors are represented by a single line in the drawings for improved clarity.) An engine 115 provides the motive force for the pumps as is conventional in hydraulic drive systems. Wheel set 21 is driven by hydraulic propel motor 101 that is supplied with fluid pressure by propel pump 110. The wheel set 21 is also steerable by steer cylinder 102 which is supplied with fluid pressure from auxiliary pump 114 through manifold 116. Referring more particularly to Figures 2 and 3, a large capacity storage hopper 23 is mounted on the chassis 181. The hopper 23 has a capacity approximately equal to the capacity of a single supply truck 16. The hopper, open at its top, consists of sidewalls 24, 25 and a bottom including a first inclined wall 26 joined with a second inclined wall 27 by an arcuate wall portion 28. The self-propelled storage vehicle further includes an operator's platform 29 having a horizontally disposed frame 30 supporting identical operator control stations 31 and 32. The platform 29 is preferably mounted on the chassis 181 by means of a parallel linkage system (not shown) permitting the platform 29 to be swung back and forth over the hopper 23 (between the solid and broken line positions shown in Figure 2) to facilitate operating the self-propelled vehicle in both directions. Of course, each operator control station includes the various controls for operating the hydraulic drive system of Figure 6. The storage vehicle 10 also includes an inclined conveyor means in the form of a high capacity loading conveyor 33, preferably of the drag-slat type, comprising a frame 34 having side members 35 pivotably mounted to the uprights 36 of the chassis 181 by a horizontal shaft 37. Thus, conveyor 33 can be swung vertically about the horizontal shaft 37 between the loading position shown in Figure 2 and the transport position shown in Figure 1. The swinging movement of conveyor 33 is provided by a pair of hydraulic cylinders 103 and 104 supplied with fluid pressure by auxiliary pump 114 through manifold 116, as shown in Figure 6. The drag-slat conveyor 33 has slats 85 (Figures 2 and 6) mounted on endless drag chains 86 meshing with sprocket wheels 87 fixed to shafts 45 and 46. Shaft 45 is driven by hydraulic motor 105, as shown in Figure 6, and is supplied with fluid pressure from a separate loading conveyor pump 111. The inlet end of conveyor 33 includes a trough 38 with a bumper 39 adapted to abut the back end of the supply truck 16 during the truck unloading operation. An important feature of the trough 38 is that its width is substantially the same as the width of the supply truck bed 17 such that the asphalt-aggregate material can quickly and easily be dumped from the truck 16 into the trough 38. An adjustable gate 41 is movably mounted over the inlet opening of the conveyor which is defined by the conveyor frame cover plate 42 and the lip 43 of the trough. The gate 41 is secured to the cover plate 42 by a pair of adjustable screwthread assemblies 44 such that the size of the inlet opening can be varied to regulate the flow of material into the conveyor 33. While the trough 38, adjustable gate 41 and coverplate 42 may be adequate to receive material from many types of dump trucks, for example the trucks shown in Figs. 1 and 2 (a standard dump truck or standard trailer) it will not be adequate to receive material delivered in a frameless trailer. The standard dump truck and standard trailer pivot their bed about a point very near its back such that the lip of the bed is approximately two feet (0.6m) off the ground. However, a frameless trailer, which normally has a capacity of about 24-25 tons of material is pivoted on its rear wheels about a point somewhere near the mid-point of the truck bed. Accordingly, the lip of the truck bed from which material is delivered can be as low as about 7-10 inches (0.17-0.25m) off the ground when tilted to deliver material. To accommodate the use of the frameless trailer and also to provide an enlarged trough which can temporarily hold a significant volume of paving material, the conveyor can be provided with a retractible trough 122 as shown in Figs. 7-10. In more detail, in Figs. 7-10, the apparatus in the form of a self-propelled storage vehicle having a retractible trough 122, is generally designated as 120. The self-propelled storage vehicle 120 is similar to the storage vehicle 10 as illustrated in Figs. 1 to 6. Accordingly like reference numerals have been used to designate like or similar parts. Conveyor 33 is now equipped with a retractible trough 122 extending from its inlet. The trough 122 comprises a first portion adjacent the inlet similar to the trough 38 and a second portion 160. The first portion comprises a curved bottom wall 124 which is pivotally connected to a floor 126 of the second portion at pivot hinge 128. Floor 126 has side walls 130 attached on either of its longitudinal ends, and a transverse wall 132. Side walls 130 are generally rectangular in shape but have extended portion 134 which extends about hinge 128 inside of side walls 136 of the first portion. Side wall 130 can slide relative to side walls 136. The walls 130, 136 are adjacent one another such that material may not pass between them as the second trough portion moves relative to the first trough when the trough is extended and retracted. The trough 122 is retractible in the direction of the longitudinal axis of the conveyor 33 towards the inlet whereby the trough volume is reduced for moving material into the inlet. Transverse wall 132 has angled upper portion 138 which projects away from the inlet and terminates in lip 140 which projects approximately parallel to the floor 126. Inclined plate 142 runs between floor 126 and transverse wall 132 on the inside of the trough 122 between side walls 130. This inclined plate 142 encourages material towards the inlet of the conveyor 33 and avoids wedging of paving material in the front corner 144 of the trough 122. The combination of trough floor 126, transverse wall 132, and side walls 130 define a second trough portion which is capable of holding paving material. Preferably, the trough 122 is approximately the width of the dump truck or standard or frameless trailer. When it is this width, the trough will hold approximately one ton of paving material. The trough 122 is actuated by hydraulic cylinder 146 connected to the conveyor at hinge 148 and to the trough at hinge 150. Hinge 150 is connected to the trough by bracket 152 which is welded at one end to the side wall 130. The bracket 152 has a projecting portion which is pivotally connected to the distal end of hydraulic cylinder 148. When hydraulic cylinder 146 is contracted, the second trough portion is pivoted about hinge 128 to be in an upward position with trough floor 126 approximately vertical. Side walls 130 slide inside of first portion side walls 136 during this operation and any material in the trough 122, resting on floor 126, is slid into the conveyor 33. As shown in Fig. 7, a frameless trailer, schematically shown as 154, is tilted to dump its contents of paving material into the trough 122. In this position the lower lip 156 of the bed of the frameless trailer 154 is below the trough lip 140 and between transverse wall 132 and conveyor 33. Accordingly, the contents of frameless trailer 154 are easily deposited in the trough 122. As previously mentioned, in the preferred embodiment, approximately one ton of paving material can be contained in the trough as herein described. Although the lowest edge 156 of the frameless trailer will be as low as seven inches (0.17m) from the ground when dumping paving material, in a preferred embodiment, the top of trough floor 126 will only be about five and three-quarter inches (5-3/4") (0.145m) from the ground (the conveyor itself being about one and one-half (1-1/2") (0.04m) off the ground). Thus, a frameless trailer will be able to completely empty its bed into the trough without interference from either the transverse wall 132 or the floor 126 of the trough 122. While the trough is being filled, material is piled up to a level where it will be swept into conveyor 33 by slats 85 on endless drag chains 86, as shown in Figs. 2 and 3. After the truck is emptied, it can depart from the conveyor leaving about one ton of material in the trough. After the material which naturally slides into the conveyor inlet is almost entirely fed in, the hydraulic cylinder 146 can be retracted to pivot the trough floor 126 upward thereby reducing the volume of the trough and gradually introduce the remaining material into the conveyor 33. After the hydraulic cylinder is completely retracted, and all the material has been emptied into the conveyor inlet, the hydraulic cylinder 146 is extended and the floor 126 pivoted down, parallel to the ground, returned to its empty state. The adjustable gate 41 (shown in Figs. 1-3 and described above) can be used in association with the trough 122. Application of adjustable gate 41 with the trough 122 is shown in Fig. 11. It is desirable that the flow of paving material placed in the trough is restricted by the gate 41 to, at most, the rate at which the drag chains move material to the hopper. Thus, jamming of the drag chain by the free flow of paving material in the trough is avoided. The adjustable gate 41 can be used with the trough 122 to restrict material flow into the conveyor without extending more than a fraction of the distance across the trough. This is accomplished by taking advantage of the natural angle of repose (shown as 153 in Fig. 11) which is the angle at which material is stable within the trough. That is, the material within the angle of repose will not flow downward toward the conveyor inlet. Only material outside (or above) the angle will slide toward the inlet. Thus, the material within the angle of repose acts as a flow barrier on one side while the adjustable gate 41 restricts flow of material on the other side. Only material within the two barriers (shown as 155) will move toward the conveyor inlet. The gate 41 can be adjusted to be closer or farther away from the material within the angle of repose in order to adjust the flow of material to be equal to (or less than) the capacity of the conveyor 33. Changes in the gate position are necessary to adjust for the different characteristics of the paving material being used in the particular application (which may change the angle of repose and/or the capacity of the conveyor) and for the operating speed of the conveyor. After all the material in truck bed 17 is emptied, the material remaining in the trough and within the angle of repose is fed into the conveyor by actuating the trough 122 to slowly raise the trough floor 126. The material raised above the angle of repose 153 by the raising of the trough floor 126 will slide toward the conveyor inlet. As the floor 126 reaches (and surpasses) the angle of repose 153, all the material in the trough is fed into the conveyor 33. In the event the trough floor 126 is raised too quickly, the adjustable gate will restrict flow of paving material to at most the desired maximum flow (for which gate 41 has been set). The use of the retractible trough 122 allows a frameless trailer which would not be able to completely empty its trailer into the trough 38 as shown in Fig. 2 to be used in conjunction with the self-propelled storage vehicle 120. Further, for all trucks, even standard dumps and standard trailers, the trough 122 provides for increased storage capacity at the conveyor inlet and allows the trucks to deposit their last one ton of paving material and depart the vehicle 120 for re-loading or other jobs. Also, due to the height of transverse wall 132 and the length of trough floor 126 extending under the lip of the truck or trailer, less material is scattered on the ground when the truck lowers its bed at the time of departing the conveyor. Further, paving material is less likely to be spilled during its delivery to the trough and upon departure of the delivery truck. The bottom wall of conveyor 33 terminates at a position just inside of the bottom wall 27 of the hopper such that the aggregate-asphalt material will fall into the hopper as the slats of the conveyor push the material past this position, as shown in the cut-away section of Figure 2. Mounted on the inside surface of the hopper bottom wall 26 is a first discharge conveyor 47, as shown in Figures 2, 3, 5 and 6, which is preferably of the drag-slat type. The discharge conveyor 47 includes a first set of sprocket wheels 88 fixed to shaft 48. Hydraulic motor 106 drives shaft 48 and is provided with fluid pressure by a separate discharge pump 112. A housing, consisting of a top wall 49 and a pair of opposed sidewalls 50, completely encloses the conveyor 47 except for openings 51 and 52 (Figure 5) located in the sidewalls 50 in the area of arcuate wall portion 28. The second shaft 53 (Figure 6) of the conveyor 47 extends through openings 51 and 52 and is journaled in suitable bearing assemblies 54 and 55, as shown in Figure 5. Sprocket wheels 56 and 57 are fixed to shaft 53 and mesh with chains 89 that, in turn, support the slats 58. The second shaft 53 of the conveyor 47 also functions as the shaft for the screw auger 60 that is disposed in the area of the hopper 23 defined by the arcuate wall portion 28 as shown in Figures 2, 3, and 5. Because the sprocket wheels 56 and 57 are fixed to the shaft 53, the hydraulic motor 106 also serves to rotate the screw auger 60. The rotation of the screw auger 60, in turn, conveys the aggregate-asphalt material from the lateral sides of the hopper, through the openings 51 and 52 and into the path of the first discharge conveyor 47. As the screw auger 60 rotates, it not only transports the material to conveyor 47 but also remixes the material such that a more uniform mixture of material is delivered to the finishing machine 12. This mixing action of the screw auger 60 is especially important because the aggregate-asphalt material has a tendency to separate according to particle size during transportation and handling. As is known to those skilled in the art, when the asphalt-aggregate material is discharged from the surge bin at the asphalt plant into the bed of the delivery truck 16, the coarser material tends to flow toward the sides of the bed of the delivery truck. Thus, this coarser material will be transported to the sides or lateral extremities of the hopper 23 since the conveyor 33 transports the material from the bed of the delivery truck to the hopper 23 without imparting transverse or lateral movement to the asphalt-aggregate material to any significant degree. Consequently, it is desirable to remix the material in the hopper 23 by imparting the requisite lateral or transverse movement of the material from the side portions to the central portion of the hopper. To this end, the screw auger 60 is designed such that each end of the shaft 53 is provided with first flight sections 61 joining with second flight sections 62. The pitch of the first flight sections 61 is greater than the pitch of the second flight sections 62. Thus, the volumes bounded by the flights of the first flight section 61 are greater than the volumes bounded by the flights of the second flight sections 62. As a result, when the coarse material, located at the lateral edges of the hopper, is conveyed from the second flight section 62 to the first flight section 61, it will not completely fill the larger volumes, thereby allowing the finer material, located in the central portion of the hopper, to enter the void spaces in these larger volumes and combine with the coarser material. This mixture of coarse and fine material is then conveyed to discharge conveyor 47. Thus, the variance in pitch between the flight sections 61 and 62 enhances the mixing capabilities of the screw auger 60. A second discharge conveyor 65 is mounted on the chassis 18 such that the infeed end of conveyor 65 is located beneath the outfeed end of the first discharge conveyor 47. Material discharged from the first discharge conveyor 47 at the top edge of bottom wall 26 falls through the chute 66 onto the second discharge conveyor 65 as shown in Figures 2, 3 and 4. The infeed end of the frame 69 of the second discharge conveyor 65 is formed with guides 67 and 68 facilitating the flow of material from the chute 66 onto the conveyor 65. Preferably, the second discharge conveyor 65 is of the belt-type having end rollers 76, 77 and an endless belt 90. Roller 77 is driven by hydraulic motor 109 supplied with fluid pressure from pump 113 as shown in Figure 6. It should be noted that a drag slat conveyor of the type already described may also be used. The frame 69 is mounted for vertical swinging movement about shaft 70 and is raised and lowered by the lift cylinder 108 extending between a first pivot point 72 located on the conveyor frame 69 and a second pivot point 73 located on a rotatable sleeve 76 supported by the chassis 181. The trunnion 74 supports shaft 70 and is mounted on a turntable supported by a suitable bearing assembly (not shown) and rotated by hydraulic cylinder 107, as shown in Figures 2 and 6, such that the discharge end of conveyor 65 may be swung beyond the lateral extremities of the storage vehicle 10. Both the vertical lift cylinder 108 and the horizontal swing cylinder 107 are provided with fluid pressure from the auxiliary pump 114 through the manifold 116. Each of the self-propelled storage vehicles 10 and 120 is able to operate in either one of two alternate modes. In the first mode of operation, illustrated in Figure 1, the storage vehicle 10, 120 shuttles between a remote location of the supply trucks 16 and the job site where the finishing machine 12 is performing the paving operation. The finishing machine 12, having the modified hopper 14 with the expanded capacity of approximately 12-20 tons, begins the paving operation with the hopper filled with aggregate-asphalt paving material. As the finishing machine 12 performs the paving operation, the storage vehicle 10, 120 travels to the remote location of the supply trucks 16 where its loading conveyor 33 is positioned adjacent the rear of one of the trucks. The paving material is dumped from the truck 16 into the trough 38, 122 where the loading conveyor 33, operating at a capacity of 800-1200 tons per hour (TPH), completely transfers the 20 tons of paving material from the truck 16 to the hopper 23, 123 in approximately one minute. The storage vehicle 10, 120 with a full load of paving material in hopper 23, 123, then travels to a position adjacent the finishing machine such that the output end of the second discharge conveyor 65 is disposed over the finishing machine's expanded hopper 14. In the time required for the storage vehicle 10, 120 to travel to the supply truck 16, transfer the paving material from the truck 16 to the hopper 23, 123, and return to the finishing machine, the supply of paving material in the finishing machine's hopper will have been nearly exhausted. Because it is desirable to have the finishing machine travel continuously, the storage vehicle operator controls the propel motor 101 so that the output end of conveyor 65 remains over the hopper 14 of the moving paving machine 12. As the two machines travel in tandem down the roadway, the auger 60, first discharge conveyor 47, and second discharge conveyor 65 are operated at a high capacity rate of 500-1200 TPH such that the 20 tons of paving material are completely transferred from the storage vehicle 10, 120 to the finishing machine hopper 14 in approximately one minute. Thus, the finishing machine may run continuously while the storage vehicle 10, 120 repeats this shuttle loading operation. In the second mode of operation, the self-propelled storage vehicle 10, 120 always travels adjacent the finishing machine 12, rather than shuttling between the remote location of the supply trucks and the finishing machine as in the first mode of operation. To coordinate the relative speeds of the two vehicles as they travel together down the roadway surface, a control linkage 80 is used between the finishing machine 12 and storage vehicle 10, 120 as shown in Figure 6. The control linkage 80 consists of a rigid finger 81 fixed to and extending from the front end of the finishing machine 12. This finger contacts a movable lever 82a of sensor 82 located on the storage vehicle 10, 120. The sensor 82 is operatively connected to an output control 83 of the propel pump 110 such that the speed of the storage vehicle 10, 120 is controlled to maintain a constant pressure on the sensor lever 82a by the finger 81. Thus, the speeds of the two vehicles, and consequently, the distance between the two vehicles are maintained constant as they travel down the roadway. It will be understood that the control linkage 80 could be eliminated and the propel motor 110 controlled by an operator to maintain the speed of the vehicle 10, 120 substantially the same as the finishing machine. Continuing with a description of the second mode of operation, the paving operation begins with the storage machine hopper 23, 123 and the finishing machine hopper 14 fully loaded with paving material. As the paving operation progresses, the storage vehicle 10, 120 begins to transfer the paving material from its hopper 23, 123 to the finishing machine hopper 14 while the two vehicles travel along the roadway together. However, unlike the first mode of operation, the paving material is discharged at a rate approximately equal to the paving rate of the finishing machine. Thus, a steady-state flow of material occurs between the storage vehicle 10, 120 and finishing machine 12. Because the paving material of the storage vehicle 10, 120 is slowly discharged onto the finishing machine hopper, it is not necessary to use a modified finishing machine with the expanded hopper 14. Thus, a conventional finishing machine may be used. However, it is preferable to use the expanded hopper 14 because the greater the combined storage capacity of the storage vehicle 10, 120 and the finishing machine 12, the fewer trucks needed to keep the storage vehicle 10, 120 loaded, which, of course, translates into a cost reduction for the paving operation. In either the first or second mode of operation, the vertical and horizontal swinging of the second discharge conveyor 65 allows the storage vehicle 10, 120 to feed the finishing machine hopper 14 even when the two machines are riding on surfaces having different elevations or when the machines are travelling offline or side by side. The horizontal swinging movement of the conveyor 65 also facilitates the feeding of the material when the vehicles are rounding corners. The paving method and apparatus described herein provide a more efficient loading capability for the finishing machine that results in a higher quality paved surface. As illustrated in Table III (set forth below), the storage vehicle and finishing machine, when used in the first mode of operation, can pave continuously at a rate of 500 TPH while still allowing a 1.5 minute truck exchange time. This is a 300 TPH increase over the prior art system referred to in Table I. Moreover, in the second mode of operation, where the supply of paving material from the storage machine is continuous, the paving rate of the system is increased such that it is substantially equal to the maximum paving rate of the finishing machine. In either mode of operation, the paving operation runs continuously to provide a higher quality paved surface having no undesirable depressions or lumps. Although the invention has been described in its preferred forms with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only. Numerous changes in the details and construction of the combination and arrangement of parts will be apparent without departing from the spirit and scope of the invention, as defined in the appended claims.

Claims: An apparatus (120) capable of receiving material from a delivery truck, (16) which apparatus comprises inclined conveyor means (33) mounted on chassis means (181), said conveyor means having a longitudinal axis, an upper discharge portion and a lower inlet and a trough (122) which extends from said inlet to receive material from the delivery truck characterised in that said trough (122) is retractible in the direction of said longitudinal axis towards said inlet whereby the trough volume is reduced for moving material into the inlet. An apparatus as claimed in claim 1, wherein the trough (122) comprises a floor (126) which has two longitudinal edges and two side edges, the floor being pivotable at one longitudinal edge towards the inlet and provided at the other longitudinal edge with a transverse wall (132), the trough also having two side walls (130) extending between the side edges of the floor and the transverse wall. An apparatus as claimed in claim 2, further comprising lifting means (146) connected between the conveyor means (33) and said trough (122) to pivot said trough floor (126) about said one longitudinal edge thereof. An apparatus as claimed in claim 3, wherein the lifting means comprises a hydraulic cylinder (146). An apparatus as claimed in claim 4, wherein said hydraulic cylinder (146) is connected between the conveyor means (33) and a side wall (130). An apparatus as claimed in any one of claims 2 to 5, wherein the transverse wall (132) has an upper portion (138) projecting away from the inlet. An apparatus as claimed in any one of claims 2 to 6, wherein said transverse wall (132) has a lip (140) projecting approximately parallel to the trough floor (126). An apparatus as claimed in any one of claims 2 to 7 wherein said trough has a first portion adjacent the inlet and comprising a bottom wall (124) and wherein the trough floor (126) is pivotally attached to said bottom wall. An apparatus as claimed in any one of claims 2 to 7 wherein the trough has a first portion adjacent the inlet and comprising side walls (136) and a bottom wall (124), and wherein the trough floor (126) is pivotally connected to the bottom wall (124) and each trough side wall (130) is adjacent a respective first portion side wall (136) and capable of slidable movement relative thereto. An apparatus as claimed in claim 9, wherein the bottom wall (124) is curved. An apparatus as claimed in any one of the preceding claims, further comprising a gate means (41) connected to the conveyor means (33) for partially restricting flow of material from the trough (122) into the conveyor means. An apparatus as claimed in claim 11, wherein the gate means (41) is adjustable. An apparatus as claimed in claim 11 or 12 wherein the trough (122) is capable of holding material which defines an angle of repose (153), and wherein the material received from the delivery truck must flow between the gate means (41) and the angle of repose in order to reach the conveyor means (33). A method of transferring material from a delivery truck (16) to a self propelled mobile apparatus (120), which apparatus comprises an inclined conveyor means (33) having a longitudinal axis, an upper discharge portion and a lower inlet, the method including providing a trough (122) extending from said inlet to receive material from the delivery truck and being characterized by the steps of extending said trough in the direction of said longitudinal axis away from said inlet to expand the trough holding capacity, discharging material from the delivery truck into the trough and retracting the trough in the direction of said longitudinal axis towards said inlet whereby the trough volume is reduced, to feed material into said lower inlet of said conveyor means. A method as claimed in claim 14, further comprising the step of re-extending the trough (122) after it is emptied of material. A method as claimed in claim 14 or 15, wherein the material is discharged from a frameless trailer (154). A method as claimed in claim 14, 15 or 16 wherein the self-propelled mobile apparatus (120) further comprises gate means (41) projecting into the trough, the method further comprising the step of limiting the feed of material into the inlet of the conveyor means to material between the gate means and an angle of repose (153) of material in the trough. A method as claimed in claim 17 wherein the trough (122) has a floor (126) and the floor of the trough is pivoted to at least the angle of repose (153).

Inventors: BASSETT JAMES HOWARD, BROCK JAMES DONALD, RENNECK JOHN PHILLIP, SMITH DONALD W, BASSETT, JAMES HOWARD, BROCK, JAMES DONALD, RENNECK, JOHN PHILLIP, SMITH, DONALD W.
Applicants: ASTEC IND, ASTEC INDUSTRIES, INC.
Application year: 1989
Main classification: E01C19
IPC codes: B60P1, E01C19