1. Field of Art
This invention relates to the improvement of an agricultural ground-working cultivator. More specifically it relates to an improvement of the cultivator hitch for towing an air cart.
2. Description of Prior Art
The need to till and cultivate soil for the planting of crops has been accomplished since the earliest days of civilization. More recently, tillage devices have increased in complexity and size, depending on the type of crops, quantity and soil being tilled. There has also been an increased emphasis on conserving natural resources resulting in these concerns being integrated in modern tillage systems. These concerns have resulted in larger and more complex tillage systems that assist in achieving these goals. A larger tillage system allows a single operator to perform tillage operations on a greater area. More sophisticated tillage systems further allow for the accomplishment of low till and no till farming techniques. Low till and no till farming encourages tilling, planting and fertilizing in a single pass of the tillage device or cultivator through the field. By only disturbing the soil a single time, there is less soil compaction, less moisture loss, less pesticides and herbicides needed and less fertilizer required. However, these larger and more complex tillage systems create complexities that were previously unknown in the art.
Previously, an agricultural tractor could pull a relatively small tillage device or cultivator. Later, a planter or similar seeding apparatus could pass over the field. However, it is now possible to make a single pass over the field. This allows both tilling and planting to be accomplished in one pass. To assist this goal, a tractor will pull a cultivator. The cultivator then pulls an air cart that can carry seeds, fertilizer or herbicide. FIGS. 1 and 2 illustrate a typical design configuration. As specifically seen in FIG. 2, there is a tractor 3 towing a large cultivator 1 or tillage device. Attached to the cultivator by a hitch is the air cart 2. The cultivator is supported by a series of castor wheels 5 located generally towards the front of the cultivator 2 and packing wheels 6, at the rear of the cultivator 1. Between the castor wheels 5 and packing wheels 6 are the tool bars 7. The tool bars 7 have various ground-working implements (not shown) attached. Usually, the ground-working tools open the soil, plants the seed and places fertilizer. The packing wheels then closes the soil. It is important that the packers track properly behind the ground working tools so that the packing is properly achieved on the row and not skewed to either side. The addition of a towed air cart 2 creates certain problems. As illustrated in FIG. 1, as the tractor (not shown) and cultivator 1 frequently move over a hills, the air cart 1 has a tendency to slide or pull the cultivator 1 to the left or right. This problem creates several undesirable effects. First, it creates `stripping`. Stripping is the resulting un-tilled ground caused when the shank pattern is skewed and pulled somewhat side-ways rather than the full till effect when the implement is tracking properly in a straight forward position. Second, ridges are created in the soil caused by packing wheels being skewed over the direction of travel. Third, failure to maintain `on-row-packing` because the packing wheels are not aligned over the seed rows. Fourth, `ridging` caused by the air cart front castor wheels skewing from a forward alignment when the air cart is out of line with the direction of travel. Fifth, when the cultivator reaches the end of a row and turns around, there is a tremendous stress placed on the cultivator when the air cart turns. This effect is similar to `crack the whip`. Complicating these issues, is the need to be able to easily transport the cultivator and air cart from field to field. After field operations, the cultivator is converted from the field mode to more compact transport mode. Typically, this involves folding the wings of the cultivator towards the center of the cultivator (as seen in FIG. 12). It is important to be able to maintain the air cart securely during transport. It would also be advantageous to minimize the operator's duties when setting up the cultivator and air cart for either transport or field modes.
The prior art has typically focused on using a cultivator hitch as illustrated in FIG. 2. This results in 2 attachment points on the cultivator and 1 attachment on the air cart. This design creates a large moment arm (d.sub.hp) from the tractor hitch 8 to the air cart 2. This large moment arm results in undesirable forces be placed on the cultivator creating the previously discussed problems.
Consequently, the need exists for an adjustable cultivator hitch for towing an air cart. Furthermore, the hitch needs to be capable of allowing the cultivator to be adjusted from the field mode to the transport mode with a minimum of operator intervention.