The invention is directed generally to improvements in asphalt pavers of the floating screed type. In particular, the invention is directed to improvements in the mounting and positioning of the auger mechanisms typically employed with such pavers.
In the laying of asphalt pavement roadways, it is common practice to utilize floating screed type paving machines. These machines typically include a tractor-like vehicle having an engine for propulsion and for material distributing functions. A material receiving hopper is provided at the front of the paver, arranged to receive hot asphalt materials from a truck, as the paving machine advances along the roadbed. Means, such as slat conveyors, are provided to convey the asphalt material rearward from the hopper and to deposit the material on the roadway, in front of the floating screed.
Directly in front of the screed, there is provided a distributing auger mechanism, comprising left and right side augers positioned in the region in which the asphalt is deposited from the slat conveyors. As the machine advances along the prepared roadbed, the raw asphalt material is first deposited by the slat conveyors and then distributed laterally outward by the augers. The distributed material then flows under the floating screed, which levels, smooths and compacts the asphalt to provide a continuous, level pavement mat.
Conventionally, the auger elements are mounted at the back of the paver in a substantially fixed position. While means typically may be provided to enable limited vertical adjustment of the augers, the nature of the known equipment is such that adjustments are rarely if ever be utilized after the initial setting. Historically, height adjustment of the auger mechanism has involved multiple manual adjustments of turnbuckles and bearing mounts, in some instances at locations which may be heavily coated with asphalt. Accordingly, adjustment of the auger height with the paver on the move has been altogether out of the question, and adjustment at other times is sufficiently complex and time consuming as to rule it out for most purposes.
In accordance with the present invention, a novel and improved arrangement is provided for constructing and mounting the auger and auger drive mechanisms for limited vertical liftability and height adjustment relative to the tractor frame, such that the auger can be instantly and effortlessly raised or lowered relative to the paver.
One of the important advantages of the mechanism of the invention resides in the fact that the auger may be set relatively close to the roadbed for normal paving operations, to achieve optimum function during paving, and yet may be instantly raised to clear roadbed obstructions, for example, such as manhole projections. In addition, for loading of the paver onto a low boy trailer or the like, for transportation to a new site, it is possible to quickly raise the auger mechanism up out of the way, providing sufficient clearance at the back of the paver to enable it to travel up a sharp incline onto the trailer bed without damaging the auger mechanism.
Pursuant to one aspect of the invention, the new liftable auger mechanism includes a drive box, which is mounted centrally, at the back of the paver, and supports the inboard ends of each of the left and right side auger elements. Support for the outboard ends of the augers is provided by means of a laterally extending cantilever beam, which is carried by the drive box and extends outward over the top of the auger elements. At one or more outboard locations, depending upon the length of the auger elements, support bearings are provided, extending downward from the cantilever beam.
In a preferred form of the invention, the entire auger mechanism is supported for limited movement by pivotal attachment of the drive box to the back of the paver frame. A hydraulic lift mechanism engages the cantilever beam at relatively widely spaced points, on opposite sides of the drive box, in order to pivot the assembly. The pivot axis of the drive box is located forwardly of the auger and generally at the same horizontal level, such that pivoting movement of the drive box is translated into generally vertical movement of the augers.
Desirably, the laterally extending cantilever beam is movably supported by the paver frame at spaced outboard locations, to provide for mechanical stability of the entire structure. Additionally, thrust resisting means may be provided respectively on the cantilever beams and paver frame, to assist in resisting the unbalanced sideways thrusting forces developed by the augers during normal paving operations.
To advantage, the new auger mechanism is constructed as a substantially unitary module, which can be installed on and removed from the paver substantially as a single unit, greatly facilitating assembly, maintenance and repair operations.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings.