Four-bar linkage for suspending a header for an agricultural implement

A suspension system for agricultural implements having at least one floating head using a four-bar linkage and permitting the floating head to accommodate variations in ground surface elevation in a lateral or transverse direction. By permitting the floating head to float, a more consistent cutting height is realized when ground surface elevation varies in a transverse direction. A main frame is provided to which the ground engaging wheels are attached. A sub-frame is connected to the main frame via the four-bar linkage. The sub-frame is pivotally attached to the arms of the four-bar linkage by spherical bearings.

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an agricultural implement, including a floating work tool. More particularly, the present invention relates to an improved suspension system for agricultural implements having one or more floating work tools.

2. Background Art

Ground on which forage crops or other foliage needing mowing is grown is rarely smooth. Such ground essentially always varies in level both in a direction of travel of the mowing machine or harvester, and in a transverse or lateral direction.

Mowing machines having a variable height cutter have been available for decades. Mounted sickle mowers used in the mid-twentieth century could be raised and lowered using the tractor lift system. Towed mowers, by necessity, were made so the header could be raised and lowered, at least between an operating position and a transport position.

In U.S. Pat. No. 6,250,055, a mower header suspension system is disclosed. The suspension system comprises a pair of lower linkage arms and a single upper suspension arm. Provision for changes in ground elevation in the direction of travel is disclosed.

Disclosed in U.S. Pat. No. 6,055,800 is a mower header suspension system providing a variable header angle compared to the longitudinal direction. The disclosed mechanism comprises two lower linkage arms and a single upper linkage arms.

The above described header suspension systems provide for changing the height of cut relative to the ground surface supporting the ground engaging wheels of the tractor or towed mower, but do not provide for a consistent cut height on ground that varies in level both in the direction of travel and in the lateral direction.

There is, therefore, a need for a method and apparatus for providing flexibility in header position to permit the header to raise and lower as ground elevation changes, and to rotate to adjust to lateral variations in ground surface levels.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a suspension system that enables a header or work tool of a towed implement to be raised and lowered, and also permit the header or work tool to follow the variable ground contour, resulting in a consistent cut height despite the variability of the ground elevation.

For the purposes of this document, including the claims, a towed implement is an implement with ground engaging means, for example wheels, independent of the source of motive power, for example a farm tractor; additionally, the towed implement has a frame or other component that may be raised and lowered relative to the ground engaging means independent of a lift, such as a standard three-point or two-point lift system of the source of motive power. Therefore, a towed vehicle is pulled by the source of motive power and may use the source of motive power's hydraulic system for raising and lowering, but does not make use of lift arms usually attached to a farm tractor.

The mower comprises two integrated frames connected by two sets of linkages to create a four-bar linkage. The two sets of linkages are maintained parallel to one another, so that the two frames are maintained at a known orientation to one another as the header is raised and lowered.

The upper linkage set comprises two “bars,” oriented at angles with respect to a longitudinal axis of the mower such that they connect to the sub-frame at points nearer the longitudinal axis than those points at which they connect to the main frame.

In contrast, the lower links are angled such that they connect to the sub-frame at points farther from the longitudinal axis than those points at which the lower links connect to the main frame.

Spherical bearings are used to connect each independent bar of the lower linkage set to the main frame and to the sub-frame. As well, spherical bearings are also used to connect the upper linkage bars to the sub-frame. The upper linkage bars are pivotally attached to the main frame by cylindrical bearings.

In a first embodiment, the upper linkage bars are permanently connected to one another where the upper linkage bars converge at the sub-frame, and are subsequently connected to the sub-frame using a single spherical bearing. In an alternative embodiment, the two bars are not directly connected to one another, but are pivotally connected to the sub-frame by independent spherical bearings in the same manner as the lower linkage bars.

The linkage arrangement herein described allows the sub-frame the ability to rotate about an axis of rotation parallel to the longitudinal axis of the mower. This ability is called “float” and refers to the capability of the mower to adjust itself automatically to a ground slope perpendicular to the direction of travel.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals indicate identical or corresponding parts throughout the several views, the present invention comprises a suspension system for an agricultural mower1, shown in its entirety inFIGS. 1a,1b,6a, and6b. The mower1comprises two integrated frames10,15. A tongue2extending over the machine is pivotally connected to a top of a main frame15, positioned at the extreme rear of the agricultural mower1. The main frame15has left and right legs mounted atop axles between two ground engaging wheels for supporting the agricultural mower1on the ground65. The axis of rotation of these wheels is substantially perpendicular to a direction of travel. A sub-frame10is pivotally connected to the main frame15, forward of the main frame15by means of a four-bar linkage system. The sub-frame10is a two part frame, suspending the work tool or cutter bar9.

The tongue2is preferably connected to an agricultural tractor (not shown). The mower1is normally drawn in a direction toward the tongue2, which direction is hereby defined as the forward direction. Based on this, the rearward direction is hereby defined for the purposes of this document, including the claims as opposite the forward direction.

A front of the mower1is likewise hereby defined as the general portion of the mower1in the lead as the mower1is drawn in the forward direction. A rear of the mower1is hereby defined as the general portion of the mower1seen when viewed from a side of the mower1opposite the tongue and facing in the forward direction.

A longitudinal direction is hereby defined as a direction parallel to the forward direction. A transverse direction is hereby defined as a direction perpendicular to the longitudinal direction, and parallel to an appropriate average of a slope of the ground surface in the vicinity of a header6.

The above definitions are defined for the purposes of this document, including the claims.

The present invention comprises a four-bar linkage system including an upper set of linkages12and a lower set of linkages11, each comprising two bars as illustrated inFIGS. 2-4and7-10. The upper linkage set12and the lower linkage set11are substantially parallel to one another when considering a side elevation view such as those featured inFIGS. 1aand1b. As shown in the plan views ofFIGS. 5aand5b, and the rear elevation view,FIG. 7, the bars belonging to the upper linkage set12are oriented in such a way as to be angled with respect to a longitudinal axis52of the mower1. More precisely, the upper links12are angled such that they connect to the sub-frame10at points nearer the longitudinal axis52than those points at which the upper links12connect to the main frame15. The lower links11are angled such that they connect to the sub-frame10at points farther from the longitudinal axis52than those points at which the lower links11connect to the main frame15.

Each independent bar of the lower linkage set11is pivotally connected to the main frame15by a spherical bearing, also known as a ball joint, at a first point and is pivotally connected to the sub-frame10by a spherical bearing, also known as a ball joint, at a second point.

As illustrated inFIGS. 7-10, each bar of the upper linkage12is pivotally connected to the main frame15by a cylindrical bearing at a first point and pivotally connected to the sub-frame10by a spherical bearing, also known as a ball joint, at a second point. In a first embodiment, the upper linkage bars12are rigidly affixed to one another where the upper linkage bars12converge at the sub-frame10, and are connected to the sub-frame10with a single spherical bearing, as shown inFIG. 7. In a second embodiment, illustrated inFIG. 8, the two bars upper linkage bars12are not directly connected to one another, but are pivotally connected to the sub-frame10by independent spherical bearings in the same manner as the lower linkage bars11. In this second embodiment, the ends of the upper linkage bars12nearest the sub-frame10are disposed closer together than their ends nearest the main frame15. In either of the first and second embodiment, the lower linkage bars11diverge from one another as they extend from the main frame15to the sub-frame10.

In a third embodiment, the lower link arms11are rigidly affixed to one another where the lower linkage bars11converge at the sub-frame10, and are connected to the sub-frame10with a single spherical bearing, as shown inFIG. 9. In a fourth embodiment, illustrated inFIG. 10, the two lower linkage bars11are not directly connected to one another, but are pivotally connected to the sub-frame10by independent spherical bearings in the same manner as the upper linkage bars12. In this fourth embodiment, the ends of the lower linkage bars11nearest the sub-frame10are disposed closer together than their ends nearest the main frame15. In either of the first and second embodiment, the upper linkage bars12diverge from one another as they extend from the main frame15to the sub-frame10.

The linkage arrangement described above allows the sub-frame10to rotate about an axis of rotation parallel to the longitudinal axis52. This ability is hereby defined as float for the purposed of this document, including the claims, and implies the capability of the mower1to adjust itself automatically to a ground slope perpendicular to the direction of travel. As illustrated especially inFIGS. 5a,5b,6a, and6b, the two independent headers6are supported independently by their respective arms8on cylindrical bearings, allowing each cutter bar9to float independently. Therefore, the undersides of the cutter bars9engage the ground surface65with greater consistency due to their floating ability.

The two arms8, pivotally mounted to the top of the forward portion of the sub-frame10, have a vertical axis of rotation. The cutter bars9mounted from these arms8are then allowed to pivot toward or away from the longitudinal axis52. As shown inFIGS. 1a,5a, and6a, in a transport position, the arms8are rotated forward, thereby decreasing a width of the mower1. In an operating mode, illustrated inFIGS. 1b,5band6b, the arms8are rotated toward the rear of the mower1such that the two separate cutter bars9form a single row perpendicular to the direction of travel. The sub-frame lift cylinder14is used to raise the sub-frame10off the ground65for transport. The sub-frame10is provided with a locking arrangement for the transport position to eliminate the risk of the sub-frame10dropping to the ground65during transport.

The present invention realizes significant benefit in that the suspension system mounts the sub-frame10in such a way as to give the sub-frame10multi-directional motion freedoms such that the underside of the cutter bar9is allowed to more consistently engage the ground surface65as the ground surface65varies. This results in the benefit of a more consistent cut height.

Another significant benefit is realized by the converging and diverging arrangements of the lower linkage bars11and the upper linkage bars12, in combination with the illustrated orientation sub-frame lift cylinder14. Due to the lower linkage bars11being in tension whenever the sub-frame lift cylinder14is retracted, the header6is self-leveling when in the transport position, while the header6is permitted to be parallel to the ground when in the operating position. Further, due to the tension in the lower linkage bars11, the header will tend to center itself relative to the main frame15on retraction of the sub-frame lift cylinder14.

An additional leveling feature is illustrated inFIGS. 11a-12b. As the header is raised from the operating position (FIGS. 11aand11b), to the transport position (FIGS. 12aand12b), and the upper linkage bars12reach an extreme raised position, they make contact with a leveling bracket75, causing the sub-frame10,62to become parallel to the ground contour in the transverse direction. A benefit is that if one side of the header becomes heavy due to accumulation of crop material, etc., it will still become level. This also keeps the sub-frame10from swaying while the agricultural mower1is in its transport position.

The embodiments of the novel suspension system herein described may be utilized for any implement making use of a floating work tool. The invention is not intended to be limited to agricultural mowers.

The above embodiments are the preferred embodiments, but this invention is not limited thereto. It is, therefore, apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.