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 vary 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.