1. Field of the Invention
This invention relates to grain stirring apparatus and more particularly to grain stirring apparatus for stirring and aerating grain ot prevent spoilage thereof, the apparatus being effective to stir and aerate the grain in a region of generally rectangular shape. The apparatus of the invention automatically responds to variations in grain conditions and avoids undue stresses on component parts thereof. It is very efficient while being trouble-free and reliable in operation, and it is economically manufacturable.
2. Background of the Prior Art
An apparatus for stirring and aerating grain is disclosed in the Sukup U.S. Pat. No. 3,584,852 in which a stirrer is formed with a helical blade and is rotated about a vertical axis while being moved horizontally in a path such that substantially all grain in a bin may be periodically stirred and aerated. In apparatus for a circular bin as illustrated in said patent, a carriage is rotated about a central vertical axis of the bin while a carrier structure on the carriage is moved back and forth, radially inwardly and outwardly, the stirrer being suppported from the carrier structure.
A similar type of apparatus for a circular bin is shown in the Murphy U.S. Pat. No. 3,251,582 which discloses electrical circuitry for automatically controlling energization of a drive motor which effects rotation of a carriage or bridge about a central vertical axis of a bin, a stirrer or auger and an associated drive motor being supported through a universal joint from a structure which is movable radially inwardly and outwardly. The universal joint allows the stirrer or auger to tilt or trail back in response to resistance of the grain during movement through the grain and the drive motor for the auger is offset so that its gravity applies a torque about the tilt axis. A mercury switch is provided on the auger drive motor and is connected in series with the bridge drive motor, the mercury switch being opened when the auger tilts beyond a certain angle. The arrangement is limited to a circular bin in which the stirrer or auger is always moved in one direction about a central axis of the bin. It is also limited in that with rotation at a constant angular velocity about the central axis of the bin, the velocity movement of the auger and thereby the reaction forces applied thereto by the grain are proportional to the radial distance from the central axis which varies constantly during the radial inward and outward movements of the auger.
It is also known in the prior art to provide apparatus for stirring grain in a rectangular bin, using a traversing mechanism which supports and journals an upper end portion of a stirrer and which effects back and forth movements of the stirrer between opposite ends of a bin and also between opposite sides of the bin.