| 摘要 |
<p>PRESS GRAIN DRILL A press grain drill includes an elongated main frame tool bar supported above the ground by at least one castored wheel, an elongated tow tube mounted in parallel, spaced-apart relation and movable with respect to the main frame tool bar by pairs of links pivotably coupled to the main frame tool bar and the tow tube and a plurality of opener units, each of which includes a selfpenetrating shovel and a press wheel and is pivotably coupled to the tow tube. The tow tube which normally resides in an operative position with the shovels and the press wheels disposed within the ground at selected depths is raised to a towing position by pneumatic cylinders to raise the opener units off the ground, a lift tube disposed in parallel, spaced-apart relation relative to the tow tube and coupled to the links via bracket members engaging the different opener units to pivot the opener units upwardly as the tow tube is raised. Each opener unit includes a plurality of elongated elements pivotably coupled to each other and to the tow tube to form a pair of parallelograms which support the selfpenetrating shovel and the press wheel respectively. Changes in the vertical position of the shovel produce changes in the vertical position of the press wheel at a greater rate and in a ratio which is fixed to provide constant depth control of the shovel and press wheel. The design configuration of the opener unit is such that the draft load on the shovel and the force provided by an included spring translate into a downward pressure on the press wheel and shovel which is substantially constant for different angular positions of the opener unit, providing a selfpenetrating unit which uniformly compacts the soil over seed deposited by the shovel.</p> |
