The present invention, relating generally to an agricultural baler for forming cylindrical bales of crop material, commonly referred to as a round baler, is directed to an improved tailgate latching apparatus. More particularly, this invention is directed toward an improved round baler tailgate latching apparatus that reduces the likelihood malfunction or damage during tailgate latching and unlatching operations.
For many years agricultural balers have been used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. Usually, a mower-conditioner cuts and conditions the crop material for windrow drying in the sun. When the cut crop material is properly dried, a baler is pulled along the windrows to pick up the crop material and form it into conveniently sized and shaped round bales. More specifically, the windrow pickup of the baler gathers the cut and windrowed crop material and lifts it into the baling chamber. In a round baler, the baling chamber consists of a pair of opposing sidewalls with a series of belts that rotate and compress the crop material into a cylindrical shape. When the bale has achieved a desired size and density, the operator wraps the bale to ensure that the bale maintains its shape and density. The operator then raises the tailgate of the baler and ejects the bale onto the ground. The tailgate is then closed and the cycle repeated as necessary and desired to manage the field of cut crop material. The utilization of rolls in combination with belts is shown by way of example in the round baler of U.S. Pat. No. 4,870,812, by Richard E. Jennings, et al., which is incorporated in its entirety herein by reference.
It is common practice to use a latching assembly to maintain a round baler tailgate in the closed position during bale formation in the chamber. Prior art latching mechanisms experienced, under certain crop conditions, excessive stress on the tailgate pivot pins when the hydraulic cylinder, employed to hold the latch in place during operation, exerts a force on the latch pin. This stress is applied as a rotational force on the tailgate pivot pins. Concurrently, a lateral force is incumbent on the tailgate during bale formation as the package of crop material expands within the chamber. Thus, the latch pin, which is being forced downwardly, transmits a downward force to the entire tailgate, which in turn produces the deleterious rotational force mentioned above, while at the same time a lateral force is being applied to the pivot pins, all of which could cause stress and ultimate fatigue if left uncorrected.
An improved latching mechanism designed to improve tailgate latching performance is disclosed in U.S. Pat. No. 7,520,215, by John H. Merritt, the descriptive portions of which are incorporated herein by reference. The Merritt reference discloses an adjustable tailgate latching mechanism for a round baler utilizing a movable arcuate hook-like latch catching structure attached to the latching mechanism that enables proper alignment of the tailgate latch to be established and maintained. Latching and unlatching movement of the mechanism is synchronized with and controlled by movement of the tailgate lift cylinder.
Experience with the improved tailgate latch mechanism shows that the latches remained prone to bending upon tailgate closure. Excessive variation in the relative position of elements of the latching mechanisms of the tailgate latches become problematic when latch movement in both the latching and the unlatching direction is synchronized with and controlled by the tailgate lift cylinder. As a result, the tailgate may be prevented from securely latching in a closed position for baling, opening to discharge a completed bale, or be subjected to excessive stresses. Correcting the misalignment is typically performed by grinding portions of the latching mechanism to obtain the proper fit or re-mounting tailgate latch pins to correct the misalignment. Such actions require significant effort. Furthermore, if misalignment in the tailgate latching mechanism occurs as a result of wear in the baler, correcting the problem generally means that the baler must be removed from operation, a correction that is rarely convenient to perform.
It would be a great advantage to provide a more durable tailgate latch mechanism for a round baler that features latching that is independent of the tailgate lift cylinders during tailgate closure, but requires hydraulic pressure in the lift cylinders to release the latching mechanism and allow tailgate opening overcomes the above-identified problems and disadvantages.