Abstract:
An auger/cut off assembly for a floating screed asphalt paver. The auger/cut off assembly consists of an auger mechanism with an axis of rotation and a cut off mechanism. The cut off mechanism has a concave cut off panel that rotates about the axis of the auger mechanism from an open strike off position to a closed cut off position. Because the concave cut off panel closely conforms to a portion of the circumference of the auger mechanism, the cut off mechanism provides for low ground clearance. The concave cut off panel serves the dual function of striking off the paving material when in the open strike off position and cutting off the deposit of paving material when in the closed cut off position.

Description:
FIELD OF THE INVENTION 
   This invention relates to a floating screed asphalt paver, and more particularly, relates to a floating screed paver having a floating screed and an auger/cut off assembly. The auger/cut off assembly includes an auger mechanism for distributing asphalt paving material evenly in front of the floating screed and a cut off mechanism for cutting off the flow of paving material to the floating screed when the cut off mechanism is in a closed cut off position and for striking off the paving material in front of the floating screed when the cut off mechanism is in an open strike off position. 
   BACKGROUND OF THE INVENTION 
   Most asphalt pavers employ a floating screed in which asphalt paving material is distributed in front of the floating screed as the paver moves along the roadbed to be paved. Particularly, such a conventional floating screed paver consists of a self-propelled power unit, a floating screed connected at the rear end of the power unit, a hopper at the forward end of the power unit for receiving paving material from a dump truck, a gravity feed hopper or a conveyor system for moving the paving material from the hopper to the roadbed in front of the floating screed, an auger assembly between the conveyor system and the floating screed for evenly distributing the paving material across the width of the floating screed, and a fixed strike off plate between the auger and the floating screed to control buildup of paving material in front of the floating screed. 
   The self-propelled power unit is typically mounted on tracks or rubber tires. The self-propelled power unit thereby provides the motive force for the paver along the roadbed as well as power for the operation and control of the various paving functions of the paver including functions associated with the hopper, the conveyor system, the auger, and the floating screed. 
   The hopper, mounted at the front end of the power unit, contacts the dump truck, and the power unit of the paver pushes the dump truck along the roadbed as the dump truck progressively dumps its load of paving material into the hopper. 
   The conveyor system on the paver or gravity moves the paving material from the hopper for discharge onto the roadbed. The screw auger spreads the paving material in front of and across the width of the floating screed. The fixed strike off plate controls the buildup of paving material in front of the floating screed. 
   The floating screed is commonly connected to the power unit by pivoting tow or draft arms, which allow the screed to float on the paving material. The depth of the paving material is controlled by a depth screw at each end of the screed. The screed functions to level, compact, and set the width of the paving material thereby leaving the finished asphalt slab with a uniform and smooth surface. 
   At the end of a paving pass with a conventional floating screed paver, the loose paving material that has been discharged by the conveyor system to the auger in front of the floating screed will remain on the roadbed and must be removed with a shovel by hand. In order to eliminate the labor involved in such a cleanup, prior art floating screed pavers have employed a cut off gate comprising a hinged cut off plate located in front of and below the auger. When the conventional cut off plate was activated by a hydraulic cylinder, the cut off plate would swing rearwardly into contact with the fixed strike off plate to eliminate the discharge of loose paving material onto the roadbed below the auger. The swinging cut off plate below the auger required additional ground clearance for its operation and thereby restricted how low the auger could be positioned. 
   In order for the auger to be lowered with minimum ground clearance, there is a need for a paving material cut off mechanism that does not require additional ground clearance. Moreover, there is a need for a cut off mechanism that is adjustable to varied the degree of strike off of paving material ahead of the floating screed and that can eliminate the deposit of loose paving material at the end of a paving pass. 
   In addition, there is a need for a auger/cut off assembly which may be divided into sections across the width of the paver. The auger sections can be independently operated, and the cut off mechanism sections can be independently opened and closed to control of the feed of paving material to the floating screed in discrete sections across the width of the floating screed. 
   SUMMARY OF THE INVENTION 
   The present invention satisfies the above-described need for an improved auger/cut off assembly by providing an auger/cut off assembly consisting of an auger mechanism and a cut off mechanism. The auger mechanism consists of a auger support member for supporting an auger for rotation about an axis. The cut off mechanism consists of at least one concave cut off panel that is rotated by means of an actuator about the axis of the auger between an open strike off position and a closed cut off position. Because the concave cut off panel closely conforms to a portion of the circumference of the auger, the auger/cut off assembly allows low ground clearance. 
   With the concave cut off panel in the open strike off position, the bottom of the auger is exposed so that the paving material can be discharged from the auger onto the roadbed. In addition, when the cut off panel is in the open strike off position, the leading edge of the concave cut off panel functions as a strike off edge. Moreover, because the cut off panel can be rotated between the open strike off position and the closed cut off position, the degree of engagement of the strike off edge can be continuously varied by the actuator to insure that the proper amount of paving material is removed by the strike off edge of the concave cut off panel. 
   In the closed cut off position, the concave cut off panel forms a trough beneath the auger to catch the loose paving material so that the loose paving material is not deposit on the roadbed at the end of a paving pass. Because the ends of the concave cut off panel are open, the loose paving material can be moved along the trough formed by the concave cut off panel and discharged through the open ends outboard of the floating screed paver for filling potholes or trenches for example. 
   Consequently, the concave cut off panel performs the dual function of striking off the paving material when the concave cut off panel is in the open strike off position and cutting off discharge of the paving material in front of the floating screed when the concave cut off panel is in the closed cut off position. In one embodiment of the invention, the auger/cut off assembly comprises a single auger mechanism and a single cut off mechanism. In another embodiment of the invention, the auger cut off assembly comprises a plurality of auger mechanisms and a plurality of cut off mechanisms. Particularly, in one embodiment, the concave cut off panel comprises two independently controlled concave cut off panels, and the auger comprises two independently controlled augers. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation view of a floating screed asphalt paver in accordance with the present invention. 
       FIG. 2  is a top plan view of a floating screed asphalt paver in accordance with the present invention. 
       FIG. 3  is a rear perspective view of an auger/cut off assembly for a floating screed asphalt paver in accordance with the present invention with the cut off mechanism in an open strike off position. 
       FIG. 4  is a rear perspective view of an auger/cut off assembly for a floating screed asphalt paver in accordance with the present invention with the cut off mechanism in a partially closed cut off position. 
       FIG. 5  is a side elevation view of an auger/cut off assembly for a floating screed asphalt paver in accordance with the present invention with the cut off mechanism in the open strike off position. 
       FIG. 6  is a side elevation view of an auger/cut off assembly for a floating screed asphalt paver in accordance with the present invention with the cut off mechanism in the closed cut off position. 
       FIG. 7  is a front elevation view of an auger/cut off assembly for a floating screed asphalt paver in accordance with the present invention with the cut off mechanism in the partially closed cut off position. 
       FIG. 8  is a rear perspective view of an auger/cut off assembly for a floating screed asphalt paver in accordance with the present invention with one section of the cut off mechanism in a closed cut off position and a second section of the cut off mechanism in the open strike off position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention is an auger/cut off assembly for a floating screed paver. The auger/cut off assembly comprises an auger mechanism and a cut off mechanism. The auger mechanism consists of an auger support member attached to the floating screed paver which supports an auger for rotation about an axis. The cut off mechanism consists of at least one concave cut off panel that is rotated by means of an actuator about the axis of the auger between an open strike off position and a closed cut off position. In one embodiment, the auger mechanism consists of two independently controlled augers, and the cut off mechanism consists of two concave cut off panels that are independently rotated by means of independent actuators about the axis of the augers between an open strike off position and a closed cut off position. 
   Turning to the figures,  FIG. 1  is a side elevation view of a floating screed asphalt paver  10  in accordance with the present invention. The floating screed paver  10  is designed to lay a finished slab of asphalt on a roadbed  12 . In connection with the following description of the floating screed paver  10 , references to “left” and “right” will be from the perspective of an operator at the rear of the paver  10  facing forward. Consequently, the elements shown in  FIG. 1  are the left hand elements of the paver  10 . By contrast in  FIG. 7 , the left side of the drawing represents the right hand side of the paver  10  and vice versa. With further reference to  FIG. 1 , the floating screed paver  10  comprises a self-propelled power unit  14 , an operator deck  20 , a hopper  24  with a left wing  26  and a right wing  28 , a floating screed  30 , an asphalt material conveyor system  52 , and an auger/cut off assembly  58 . 
   The self propelled power unit  14  includes a frame  15 , a motor  16 , generally a diesel engine, a hydraulic system (not shown), and crawler tracks  18 . The motor  16  provides the prime motive power for the self propelled power unit  14 . Typically, the motor  16  drives a hydraulic pump (not shown) which in turn drives hydraulic motors and cylinders to power the various functions of the floating screed paver  10 . For example, a pair of hydraulic motors (not shown) propel the paver  10  along the roadbed  12  on the crawler tracks  18 . In other embodiments of the paver  10 , rubber tires may be used instead of the crawler tracks  18 . 
   The floating screed paver  10  is controlled by an operator from the operator deck  20  by means of a control panel  22 . 
   The hopper  24  receives asphalt paving material from a dump truck (not shown) at the front end of the paver  10 . The wings  26  and  28  are controlled by means of hydraulic cylinders (not shown) to open in order to expand the width of the hopper  24  in order to receive paving material and to close in order to minimize the width of the hopper during transportation and maneuvering. 
   As shown in  FIG. 2 , the conveyor system  52  along the bottom of the hopper  24  delivers the paving material from the hopper  24  to the roadbed  12  in front of the floating screed  30 . The conveyor system  52  is divided in half across the width of the hopper and consists of a left conveyor  54  and a right conveyor  56 . Each conveyor  54  and  56  consists of the series of slats mounted at each end on a continuous chain. Each conveyor  54  and  56  is independently driven by a hydraulic motor to control the amount of paving material delivered to each half of the roadbed  12  in front of the floating screed  30 . The conveyor system  52  could also consist of a single conveyor instead of the left conveyor  54  and the right conveyor  56 . Alternatively, the conveyor system  52  could also consist of multiple conveyors extending across the width of the hopper  24 . Moreover, the conveyor system  52  may comprise a gravity feed from the hopper. 
   The floating screed  30  is attached to the power unit  14  by means of a left draft arm  40 , a right draft arm  42 , a left pivot pin  32 , and a right pivot pin  34  so that the floating screed  30  is pulled by the power unit  14  along the roadbed  12 . The floating screed  30  is raised for transportation by means of hydraulic cylinders such as left side hydraulic cylinder  36 . The floating screed  30  is supported on a left side skid  48  and on a right side skid  50  which contact the roadbed  12  when the paver  10  is not involved in a paving operation. During a paving operation, the relative height of the floating screed  30  with respect to the roadbed  12 , and therefore the thickness of the finished slab, is controlled by a left side depth screw  44  and a right side depth screw  46 . Particularly, the left side depth screw  44  and the right side depth screw  46  very the angle of attack of the floating screed  30  on each end of the floating screed  30 . 
   In order to insure proper operation of the floating screed  30 , the auger/cut off assembly  58  includes an auger mechanism  59  and a cut off mechanism  104 . The auger mechanism  59  receives the paving material from the conveyor system  52  and distributes the paving material evenly across the width of the floating screed  30  including any screed extensions for producing wider paving widths. The cut off mechanism  104  has an open strike off position ( FIGS. 3 and 5 ) and a closed cut off position (FIGS.  4  and  6 ). In the open strike off position, the cut off mechanism  104  strikes off the paving material in order to control buildup of the paving material in front of the floating screed  30 . In the closed cut off position, the cut off mechanism cuts off the flow of paving material from the conveyor system  52  to the roadbed  12  in front of the floating screed  30  thereby eliminating the deposit of loose paving material on the roadbed  12  at the end of a paving pass. 
   Turning to  FIGS. 3 and 5 , the auger/cut off assembly  58  is shown in the open strike off position. As previously stated, the auger/cut off assembly  58  consists of the auger mechanism  59  and the cut off mechanism  104 . With reference to  FIG. 7 , the auger mechanism  59  consists of an auger support member  60  and a left auger  80  and a right auger  90 . The auger support member  60  has a left mounting bracket  62  and a right mounting bracket  64  for mounting the auger support member  60  to the self-propelled power unit  14  between the outlet of the conveyor system  52  and the floating screed  30 . Auger bearing supports  66 ,  68 , and  70  extended below the auger support member  60  and carry auger bearings  72 ,  74 ,  76 , and  78 . The left auger  80  is journaled for rotation in auger bearings  72  and  74 , and the right auger  90  is journaled for rotation in auger bearings  76  and  78 . The left auger  80  and the right auger  90  both rotate about a common auger axis of rotation  100 . The left auger  80  is driven by a left hydraulic motor  82  by means of a left motor sprocket  84 , a left auger sprocket  86 , and a left drive chain  88 . Likewise, the right auger  90  is driven by a right hydraulic motor  92  by means of a right motor sprocket  94 , a right auger sprocket  96 , and a right drive chain  98 . Each of the hydraulic motors  82  and  92  are independently controllable in the forward or reverse direction by the operator from the controlled panel  22 . Also, the speed of each of the hydraulic motors  82  and  92  is independently controlled by the operator from the control panel  22 . Consequently, the augers  80  and  90  can be independently controlled to move paving material at different and variable rates from the center outward, from the sides inward, to the left, or to the right. 
   With reference to  FIG. 3 , the auger support member  60  is hollow with a series of inlet vents  65  along the length of the bottom of the support member  60  and outlets vents  67  along the front of the support member  60 . A source of vacuum (not shown) is attached to outlets vents  67  in order to draw fumes from the paving material into inlet vents  67  and away from of paving material in close proximity with the operator of the paver. In that way, the fumes can be collected and processed before being released to the atmosphere away from the operator of the paver. 
   The cut off mechanism  104  of the auger/cut off assembly  58  consists of a left concave cut off panel  106  and a right concave cut off panel  118 . As can best be seen in  FIG. 4 , the left concave cut off panel  106  has a partial hub  108  attached at one end and a partial hub  110  attached at the other end. Likewise, the left concave cut off panel  118  has a partial hub  120  attached at one end and a partial hub  122  attached at the other end. The partial hubs  108 ,  110 ,  120 , and  122  are all journaled for rotation about the augers axis of rotation  100 . The partial hubs  108  and  122  at the end of each of the concave cut off panels  106  and  118  are open. The concave cut off panels  106  and  118  have a circumference that closely matches of the circumference of the augers  80  and  90 . In addition and as shown in  FIG. 7 , the left concave cut off panel  106  has a left strike off edge  112 . Likewise, the right concave cut off panel  118  has a right strike off edge  124 . 
   The rotation of the left cut off panel  106  about the axis of rotation  100  is independently controlled by a left actuator which includes a hydraulic cylinder  114  connected between a left upper bracket  115  and a left lower bracket  117 . Likewise, the rotation of the right cut off panel  118  about the axis of rotation  100  is independently controlled by a right actuator which includes a hydraulic cylinder  126  connected between a right upper bracket  127  and a right lower bracket  129 . The upper brackets  115  and  127  are fixed to the support member  60  and the lower brackets  117  and  129  are connected to the left concave cut off panel  106  and the right concave cut off panel  118  respectively. 
     FIGS. 3 and 5  illustrate the open strike off position of the cut off mechanism  59 , and  FIGS. 4 and 6  illustrate the closed cut off position of the cut off mechanism  59 . During the continuous paving operation, the concave cut off panels  106  and  118  are rotated by means of the hydraulic cylinders  114  and  126  to the open strike off position shown in  FIGS. 3 and 5 . In the open strike off position, the strike off edges  112  and  124  of the concave cut off panels  106  and  118  strike off the paving material delivered from the conveyors  54  and  56  to the augers  80  and  90 . The depth of engagement of the strike off edges  112  and  124  can be varied by extending and retracting the hydraulic cylinders  114  and  126  thereby allowing more or less paving material to reach the leading edge of the floating screed  30 . 
   Once the paver reaches the end of paving run, the hydraulic cylinders  114  and  126  are extended so that the concave cut off panels  106  and  118  rotate to the fully closed cut off position shown in FIG.  6 . If paving material remains in the augers  80  and  90  at the time the concave cut off panels  106  and  118  are move to the closed cut off position, the augers  80  and  90  may continue to run thereby delivering the paving material to the outside ends of the concave cut off panels  106  and  118 . Because the partial end hubs  108  and  122  are open, the paving material is carried along the concave cut off panels  106  and  118  by the augers  80  and  90 , and the paving material is thus expelled from the concave cut off panels  106  and  118  on either side of the paver  10 . In that manner, loose paving material is not left on the roadbed  12  at the end of the finished slap at the end of the paving run. Any excess material is either carried in the concave cut off panels  106  and  118  or is extruded out of the ends of the cut off panels  106  and  118  to the side of the slab and out of the way. By extruded paving material out of the ends of the cut off panels  106  and  118 , the paver can be used to deliver paving material to potholes or trenches along the side of the paver. 
   Because the concave cut off panels  106  and  118  are closely fit to the diameter of the augers  80  and  90  and because the concave cut off panels  106  and  118  rotate about the augers&#39; axis of rotation  100 , the concave cut off panels  106  and  118  extend below the augers  80  and  90  only by the thickness of the concave cut off panels  106  and  118  themselves. Consequently, the configuration of the concave cut off panels  106  and  118  and their rotation about the augers&#39; axis of rotation  100  allows the augers  80  and  90  to be position close to the roadbed  12 . 
     FIG. 8  illustrates the auger/cut off assembly  58  with the left cut off panel  106  in the closed cut off position and the right cut off panel  118  in the open strike off position. With the cut off panels  106  and  118  independently position by the actuators  114  and  126  as shown in  FIG. 8 , the paver  10  can be used to pave a strip that is half the width of the paver. 
   The present invention thus contemplates an auger/cut off assembly with a single auger and single cut off panel, an auger/cut off assembly with two independently controlled augers (such as augers  80  and  90 ) and two independently controlled cut off panels (such as cut off panels  106  and  118 ), and an auger/cut off assembly with multiple independently controlled augers and multiple independently controlled cut off panels. 
   Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description.