Agricultural implement walking beam assembly

[0001] The present invention relates generally to wheel assemblies for ground working implements and, more specifically, to such assemblies which include a walking beam support arrangement.

[0002] Implement wheel assemblies often include a walking beam arrangement to allow relative vertical movement of two fore-and-aft offset wheels as the implement moves over irregular ground surfaces. Opposite ends of a fore-and-aft extending walking beam support the wheels, and the central portion of the beam is pivotally connected for rocking about a pivot location in line with the wheels to maintain a generally equal load on each of the wheels. Such an arrangement, although adequate for many implement configurations, can present space problems for some applications such as those requiring high crop clearance tires for row crop applications or for implements which are used to sidedress material. Currently, space-consuming larger diameter tires provide the necessary ground offset. Also, as the implements increase in size, the support structure for the increased weight and loads also has to be made larger and becomes more expensive.

[0003] To provide proper weight transfer without sacrificing crop clearance for row crop applications, two individual wheel arms are tied together by a linkage that pivots about a fore-and-aft extending axis at a location above the wheels and generally in line with a portion of the implement frame. The linkage assures a balance of weight transfer to the two transversely spaced wheels so that a single wheel is not overloaded. Spring members may be interposed between the ends of the pivoting linkage and the individual wheel arms to lower frame impact forces and reduce the size and weight of the frame structure. The structure allows two wheels to be placed side-by-side in weight-sharing relationship. An above-frame mounting arrangement reduces under-frame hardware and crop and soil flow impedance. Tools such as fertilizer openers may be advantageously arranged under the frame forwardly of the wheels, and the wheel support arrangement facilitates sufficient under-frame clearance for sidedressing fertilizer in tall crops.

[0004] These and other objects, features and advantages of the present invention will become apparent from the description which follows taken in view of the drawings.

[0010] Referring to FIG. 1, therein is shown a portion of an agricultural implement 10 having a main frame 12 supported for forward movement F over the ground by forward wheel assemblies 14 and 16 and aft wheel assemblies 18. The lowermost portions of the frame 12 lie generally along a horizontal plane P (FIG. 2). Earthworking tools 20 depend from the frame 12 and extend downwardly and rearwardly from central rockshaft structure 22 and from forward rockshaft structure 23 located ahead of the wheel assemblies 18.

[0011] As shown, the implement 10 is a high-speed nutrient applicator for applying chemicals such as anhydrous ammonia (NH₃) to the soil adjacent growing crops. The tools 20 each include a disk opener assembly 24 to open a slit in the soil and direct the chemical deep into the slit, and closing wheel structure 26 to seal the chemical within the slit. The implement 10 can operate in tall crops such as corn to sidedress NH₃, and therefore sufficient under-frame clearance is necessary to prevent damage to plants. Lift structure 30 rotates the rockshaft structures 22 and 23 about an axis transverse to the forward direction F to move the tools 20 downwardly into earthworking positions and to raise the tools from the ground for transport. The implement 10 includes folding wing sections 32, 34 and 36 which are movable upwardly and inwardly over a generally rectangular center section 12c of the main frame 12 to a transport position (not shown). In the transport position, the weight of the implement 10 is carried by the wheel assemblies 18, which are mounted to a transversely extending rear frame member 12r of the center section 12c and by a hitch 38 joined to, and projecting forwardly from, the center section 12c and being connected to a towing vehicle (not shown).

[0012] Referring to FIG. 2, the wheel assemblies 18 each include a wheel bracket structure 40 bolted or otherwise fixed to the rear frame member 12r and pivotally supporting leading or upper ends of downwardly and rearwardly inclined wheel arms 42 and 44 for rocking about respective wheel arm axes 42a and 44a. The wheel arms 42 and 44 have lower or trailing ends supporting first and second generally identical transversely spaced wheels 18w having rotational axes 18a. On level surfaces, the wheels 18w are side by side with the axes 18a generally coextensive. Linking structure 48 operably connects the wheel arms 42 and 44 for constraining the wheel arms to move generally in opposite vertical directions as the frame passes over the irregular surfaces to help equally distribute loads on the wheels 18w.

[0013] The linking structure 48 includes a transversely extending beam or connecting member 50 pivotally connected to the wheel bracket structure 40, which is fixed to the frame member 12r, for rocking about a fore-and-aft extending axis 50a having an upward extending component in the rearward direction (see FIG. 3). Opposite ends of the member 50 are connected by links or upright members 52 and 54 to the wheel arms 42 and 44, respectively, at locations on the wheel arms offset from the pivotal axes 42a and 44a so that as one of the wheels 18w moves downwardly over uneven terrain, the linking structure 48 constrains the opposite wheel 18w to move upwardly to evenly distribute loading between the two wheels 18w.

[0014] The bracket structure 40 is shown as a single casting or weldment (FIG. 5) particularly constructed for being mounted to the rear frame member 12r, which is defined by a tubular member having a rectangular cross-section, and for this purpose includes a transversely extending portion 60 which is reverse J-shaped in cross-section (FIG. 3) and has an upright apertured rear wall or leg 62 positioned against a rear wall of the rear frame member 12r, a horizontally disposed leg 64 abutting a bottom of the rear frame member and extending forwardly to an apertured front leg or wall 66 that embraces a front wall of the rear frame member 12r. Upper bolts 68 (FIGS. 2 and 3) extend through the rear frame member 12r and apertures in the rear leg or wall 62. Lower bolts 70 extend through apertures in the front leg or wall 66, through the rear frame member 12r and through apertures in the rear leg or wall 62. The bolts 68 and 70 firmly secure the bracket structure 40 to the frame 12. Pivot brackets or wheel arm supports 72 and 74 depend from opposite ends of the bracket structure 40, and a beam pivot bracket 78 extends rearwardly and upwardly from the rear wall or leg 62 and the bottom wall or leg 64.

[0015] The wheel arms 42 and 44 are similar in construction and each includes a pair of spaced side plates 80 having upper forward ends connected by pivot pins 82 and 84 to bushings 86 and 88 centrally located on the pivot brackets 72 and 74 of the wheel bracket structure 40 at a location below the rear frame member 12r. The pair of side plates 80 of each of the arms 42 and 44 extend rearwardly from the pivot pin locations, are joined by a transversely extending connecting member 90 (FIG. 2) located behind the rear frame member 12r, are disposed on opposite sides of an associated one of the wheels 18w and have lower or trailing ends respectively coupled to opposite ends of the wheel axle. An extension arm 92 is fixed to the connecting. member 90 in centered fore-and-aft alignment with the associated wheel 18w and extends upwardly and rearwardly from the connecting member 90 to a location spaced to the rear from an upper region of the plates 80 to an aft end pivotally connected to the lower portion of the corresponding upright link 52 or 54. Transversely extending pivot pins 96 and 98 respectively extend through the arms 92 and through the lower portions of the respective links 52 and 54.

[0016] The transversely extending beam or connecting member 50 includes first and second fore-and-aft spaced plates 100 pivotally connected to the frame 12 by a pin 102 extending through bushings 104 and 106 in the pivot bracket 78 and spaced from each other along the beam axis 50a. The upper ends of the upright links 52 and 54 extend between the plates 100 and are pivotally connected to the ends of the connecting member 50 by fore-and-aft extending pins 112 and 114. To provide necessary link freedom of motion as the member 50 pivots and as the wheels 18w pivot in opposite vertical directions about the respective arm pivotal axes 42a and 44a, additional pivotal connections are provided at link locations 116 and 118 by a transversely extending upper pivot pin 122 and a lower fore-and-aft extending pivot pin 124 to define universal joint connections between the opposite ends of the connecting member 50 and the respective wheel arms 42 and 44. The pivotal connections provide multiple degrees of freedom of movement between the wheel arms and the connecting member 50.

[0017] The above-described linking of the connecting member 50 to the wheel arms 42 and 44 provides some load transfer from the wheels 18w to the frame 12 at a location rearwardly of the wheel arm pivotal axes 42a and 44a to reduce wheel arm pivot loads. The pivotal axis 50a of the pin 102 is approximately perpendicular to a plane passing through the wheel axes 18a and the wheel arm pivotal axes 42a and 44a when the wheels 18w are side-by-side on a level surface.

[0018] In the embodiment shown in FIG. 4, links 52′ and 54′ include cushioning members 152 and 154. As shown, the cushioning members 152 and 154 are elastomeric blocks which absorb shock impacts and reduce loading on the wheel bracket structure 40′, although other cushioning or resilient members such as springs, air bags, hydraulic cylinders or accumulation devices could also be used. A single cushioning member could also be used instead of two or more members.

[0019] Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.