Patent Application
20080223591
The present invention relates generally to hitches between motorized vehicles and implements and, more particularly, to push-steer hitches between motorized vehicles and implements.
In addition to their non-agricultural uses, tractors can be hitched to many agricultural implements to achieve a variety of desired applications, such as tillage, seeding, cutting or harvesting. Formerly, the implements were hitched to the tractors and pulled behind the tractor. However, in an effort to increase productivity, it can be desirable to push one implement and pull another to increase an operating width that is up to twice the transport width of the implements.
Making implements wider can also increase efficiency, but there are problems associated with transporting the tractor/implement combination between different fields. In response to this problem, some tillage and seeding implements can be hydraulically folded into narrow transport widths. For example, in a mower conditioner arrangement, one mower conditioner is carried on the front of the tractor and two mower conditioners are pulled behind the tractor that are hydraulically folded for transport. Alternately, bidirectional tractors have included one mower conditioner mounted at the front end and another mower conditioner having a pivot tongue is pulled behind the tractor. Each of these configurations requires a tractor having front three point hitches and a power take-off (PTO), or specially designed implement frames, or implements that themselves must be specially designed, thereby greatly increasing the costs of these components.
What is needed is an implement hitch that is compatible with tractors lacking specially configured fronts, i.e., three point hitches or PTO, the hitch requiring minimal change to existing implements.
The present invention relates to a system for push-steering an implement. The system includes a pair of links, each link connecting the implement to a front portion of a motorized vehicle having a first axis. The implement has a second axis and rotatably carries at least two spaced wheels, one of the links being pivotably connected to the implement. The remaining connections between the pair of links and the front portion of the motorized vehicle and the implement are rotatable connections. The pair of connected links between the motorized vehicle and the implement are non parallel to each other. In a home position, one link of the pair of links is disposed at a first angular position with respect to the first axis and the second axis is disposed at a second angular position with respect to the first axis. An extension of the pair of links defines an instantaneous center forward of the front portion and between the at least two wheels. In response to the motorized vehicle traveling at a first predetermined steering angle with respect to the first axis, causing the motorized vehicle and the implement to travel along a substantially arcuate path, a traction element is developed between the at least two wheels of the implement and the driving surface. The traction element rotatably urges the one link toward a predetermined offset angle from the first angular position in a rotational direction opposite of the first predetermined steering angle. The pair of links simultaneously rotatably urges the implement to be steered toward a second predetermined steering angle from the second angular position in the same rotational direction as the first predetermined steering angle. The predetermined offset angle and second predetermined steering angle define a substantially stable position in response to the first predetermined steering angle.
The present invention further relates to a system for push-steering an implement. The system includes a pair of links, each link connecting the implement to a front portion of a motorized vehicle having a first axis. The implement has a second axis and rotatably carries at least two spaced wheels, one of the links being pivotably connected to the implement. The remaining connections between the pair of links and the front portion of the motorized vehicle and the implement are rotatable connections. The pair of connected links between the motorized vehicle and the implement are non parallel to each other. A weight transfer system connects the one link of the pair of links to the front portion of the motorized vehicle. In a home position, one link of the pair of links is disposed at a first angular position with respect to the first axis and the second axis is disposed at a second angular position with respect to the first axis. An extension of the pair of links defines an instantaneous center forward of the front portion and between the at least two wheels. In response to the motorized vehicle traveling at a first predetermined steering angle with respect to the first axis, causing the motorized vehicle and the implement to travel along a substantially arcuate path, a traction element is developed between the at least two wheels of the implement and the driving surface. The traction element rotatably urges the one link toward a predetermined offset angle from the first angular position in a rotational direction opposite of the first predetermined steering angle. The pair of links simultaneously rotatably urges the implement to be steered toward a second predetermined steering angle from the second angular position in the same rotational direction as the first predetermined steering angle. The predetermined offset angle and second predetermined steering angle define a substantially stable position in response to the first predetermined steering angle.
The present invention yet further relates to a method for constructing a push-steering system for an implement. The method includes providing a pair of links and connecting each link to an implement. The method further includes connecting each link to a front portion of a motorized vehicle having a first axis, the pair of connected links between the motorized vehicle and the implement being non parallel to each other. The implement has a second axis and rotatably carries at least two spaced wheels, one of the links being pivotably connected to the implement. The remaining connections between the pair of links and the front portion of the motorized vehicle and the implement are rotatable connections. The pair of connected links between the motorized vehicle and the implement are non parallel to each other. In a home position, one link of the pair of links is disposed at a first angular position with respect to the first axis and the second axis is disposed at a second angular position with respect to the first axis. An extension of the pair of links defines an instantaneous center forward of the front portion and between the at least two wheels. In response to the motorized vehicle traveling at a first predetermined steering angle with respect to the first axis, causing the motorized vehicle and the implement to travel along a substantially arcuate path, a traction element is developed between the at least two wheels of the implement and the driving surface. The traction element rotatably urges the one link toward a predetermined offset angle from the first angular position in a rotational direction opposite of the first predetermined steering angle. The pair of links simultaneously rotatably urges the implement to be steered toward a second predetermined steering angle from the second angular position in the same rotational direction as the first predetermined steering angle. The predetermined offset angle and second predetermined steering angle define a substantially stable position in response to the first predetermined steering angle.
An advantage of an embodiment of the present invention is that operating efficiencies can be significantly improved.
A further advantage of an embodiment of the present invention is that the improved operating efficiencies are achieved while minimizing costs.
A still further advantage of an embodiment of the present invention is that the system reduces the number of new parts and associated inventories.
A yet further advantage of an embodiment of the present invention is that the system pushes the implement in a stable fashion without requiring special configuring of the front portion of a motorized vehicle.
A further advantage of an embodiment of the present invention is that the system utilizes the same implement frame as used with the pull type movement.
A still further advantage of an embodiment of the present invention is that the system incorporates steering stops to prevent unstable oversteering of the implement.
A yet further advantage of an embodiment of the present invention is that the system incorporates a weight transfer system from implement to motorized vehicle.
A still yet further advantage of the present invention is that the system utilizes spring centering to help stabilize steering speed.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Referring to the drawings for a description of a hitch or push-steering system which employs the present invention,
As shown in
In addition, the three rotational connections in conjunction with the two or more wheels on the implement allow the implement to adjust to terrain relative to the tractor.
It is to be understood that while links 16, 18 are shown and referred to as a pair, it is possible that additional links can be used to help guide the push-steer system of the present invention. Therefore, the phrase “pair of links” can include more than two links, so long as the kinematic operation of the primary two links, such as links 16, 18 connecting implement 14 and tractor 12 in a manner described in further detail below is not prevented.
As shown in
The weight transfer system compensates for the center of gravity of the implement being in front of the implement wheels and causing a lifting force on the front wheels of the tractor. The adjustable weight transfer system allows the operator to distribute the weight between the implement wheels and tractor wheels to a desired ratio, such as 1:1, for stable operation.
Upon collar 62 reaching a desired position with respect to adjustment fixture 64, fastener 68, which was previously unengaged with opening 66, is then directed into engagement with both collar 62 and an aligned opening 66. In the engaged position, collar 62 is maintained in a fixed position with respect to frame 56. Extended or stretched springs 70 apply a retraction force between frame 56 and link 16 urging the end of link 16 adjacent connection 24 in rotational direction 90 (
In addition to being in connection with weight transfer system 84, link 16 is connected to implement 14 at connection 24 and which implement 14 pivots with respect to link 16 about axis 47. As shown in
Links 16, 18 of push-steering system 10, in combination with front portion 20 of tractor 12 and implement 14, form a four bar mechanism that is utilized to steer implement 14 in the same rotational direction that tractor 12 is being steered as shown in
As further schematically shown in
To provide basis for further orienting tractor 12 with respect to home position 100 and respective steering/steered positions 102, 104,
In a similar fashion to orienting wheel 32 of tractor 12 with respect to home position 100, links 16, 18 of push-steer system 10 and implement 14 are also oriented in
It is to be understood that the portions of connections for link 16, 18 are fixed with respect to each other, i.e., connections 22, 24, 26, 28. Since the distance between connections 22, 26 is greater than the distance between connections 24, 28, links 16, 18 are maintained non parallel to each other at all times.
As further shown in
As shown in
Also, as further shown in
Additionally, in response to tractor 12 traveling at steering angle 78′ and the rotatable urging of link 16 from angular position 72 toward offset angle 72′, implement 14 is simultaneously rotatably urged to be steered toward a steering angle 74′ from angular position 74. Steering angle 74′ is rotated in a rotational direction opposite that of steering angle 78′. Stated another way, from the perspective of the tractor driver facing toward front portion 20 of tractor 12, steering angle 78′ represents tractor 12 executing a left hand turn or steering the tractor 12 in a rotational direction toward a left hand turn. Similarly, from the tractor driver's perspective, steering angle 74′ represents implement 14 executing a left hand turn or steering the implement 14 in a rotational direction toward a left hand turn.
The rotatable urging of implement 14 is due to the geometry of links 16, 18 of push-steering system 10, which in combination with front portion 20 of tractor 12 and implement 14, forms a four bar mechanism. The rotatable/pivotable connections 22, 24, 26, 28 between links 16, 18, as previously discussed, and front portion 20 and implement 14 provide for rotatably urging implement 14 toward predetermined offset angle 74′ from angular position 74 in response to a given rotational movement of link 16 of offset angle 72′ from angular position 72. As appreciated by those understanding kinematics, adjustments to the locations of connections 22, 24, 26, 28 can similarly change the relative magnitudes of offset angle 72′ and 74′ for a given steering angle 78′.
Importantly, for a range of steering angles 78′ of tractor 12, there exists corresponding steering angles 74′ of implement 14 that are in equilibrium with the corresponding traction force 94. In other words, if the magnitude of steering angle 78′ were to be increased from that shown in
It is to be understood that while steering angle 78′ for tractor 12 only depicts a left hand turn, push-steering system 10 can also be used for right hand turns. Thus, tractor 12 can drive along a path resembling an “S” or serpentine path. Moreover, while link 16 is shorter that link 18 as shown in the Figures, the push-steering system of the present invention exhibits minimal biasing with respect to left hand and right hand turns. That is, while turning response for the push-steering system is not identical in each turning direction, the differences based upon kinematic studies have been minimal.
It is possible to convert an implement 14 used in a pull behind configuration, where the implement has pin connection similar to connection 24. In one embodiment, after disconnecting a hydraulic cylinder (not shown), the link used to connect the tractor to the implement 14 in a pull behind configuration can be rotated 180 degrees, acting as link 16.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
