Disc Standard Assembly

This invention relates to a cushioned standard assembly in a disc harrow implement.

"C" type springs are used in typical disc harrows to attach the disc gang to the harrow frame and to absorb motion shock therebetween. In normal harrow operation, the discs on one end of the disc gang may be less deeply sunk into the earth than the discs on the other end. This unequal depth may produce unequal working forces which act upon the two ends of the disc gang. In a harrow with conventional "C" type spring supports, these unequal working forces cause unequal deflections of "C" type spring supports associated with the disc gang. This unequal deflection causes the disc gang to pivot in a horizontal plane relative to the harrow frame so that the desired angle of the discs to the direction of travel is not maintained. It would be desirable to provide a disc gang support assembly which, while absorbing the shock due to collisions between the discs and obstacles, would reduce horizontal pivoting of the disc gang during normal operation.

It is an object of this invention to provide a disc harrow support assembly which readily yields to absorb the shock of collisions between the discs and obstacles.

It is a further object of this invention to provide a shock absorbing support assembly which substantially eliminates horizontal shifting or pivoting of the disc gang during normal operation.

These and other objects are achieved according to the applicant's invention in that it provides an improved shock absorbing support assembly for attaching a disc gang to a disc harrow frame. A pair of support assemblies support each disc gang from the harrow frame. Each support assembly includes a rigid standard with an upper end fixed to the harrow frame member. The upper end includes a rearward extending flange. The standard extends downward and slightly forward to a lower end. A bearing arm includes one end pivotally attached to the lower end of the standard. The other end of the arm carries a bearing which supports the gang bolt of the disc gang. A coil spring is attached between the flange and a yoke on the central portion of the bearing arm. An adjusting bolt, threadably attached to the yoke, extends through a bore in the flange and through the center of the coil spring and limits the separation between the arm and the flange to adjust the preload compression of the spring so that the discs are maintained at a desired depth during typical operating conditions. Disc scraper assemblies may be suspended from a frame member attached to a bracket at the rearward end of the flange.

FIG. 1 is an oblique view of a disc harrow including applicant's invention;

FIG. 2 is a top view of a disc gang assembly including applicant's invention;

FIG. 3 is a side view in the direction of arrows 3--3 of FIG. 2; and

FIG. 4 is a view of a conventional "C" type support assembly.

Referring to FIGS. 1, 2 and 3, a disc harrow 10 includes a plurality of disc gangs 12 each suspended from a frame member 14 of rectangular cross-section by at least two support assemblies 16. Each disc gang 12 includes an elongated gang bolt 18 upon which a plurality of earthworking discs 20 are mounted in a fixed axial spaced relationship.

Referring now to FIGS. 2 and 3, each support assembly 16 includes a rigid standard 22 with an upper end or frame engaging portion 23 fixed or bolted to the frame member 14. The upper end 23 includes a generally upwardly opening recess 21 which engages and receives a portion of the frame 14. The upper end of standard 22 includes a substantially rearwardly and slightly downwardly extending flange 24 with a bore or aperture 25 extending therethrough. A leg 27 of standard 22 extends substantially downward and slightly forward from upper end 23 to a lower end 26. Each support assembly 16 also includes a rigid bearing arm 28 with a forward end pivotally attached at 30 to the lower end 26 of leg 27. The pivot at 30 allows arm 28 to pivot in a vertical plane, but prevents arm 28 from pivoting in a horizontal plane relative to the leg 27. A bearing assembly 32 is bolted to the rearward end of arm 28. The bearing assembly rotatably carries the gang bolt 18 which extends therethrough. The horizontal spacing between the pivot 30 and the bearing assembly 32 is larger than the vertical spacing therebetween. Furthermore, note that the radius of the disc 20 is greater than the length of arm 28 so that the spacing between the pivot 30 and the bearing assembly 32 is not greater than the radius of the disc 20. A yoke 34 is pivotally attached to a central portion of bearing arm 28 intermediate its forward and rearward ends. The shank of a bolt 36 extends through bore or aperture 25 with a threaded end received by yoke 34. The head of bolt 36 is engagable with an upper surface of flange 24, thus limiting the downward pivoting of arm 28 and maintaining a predetermined preload or compression of a spring 38. Spring 38 is shown as a coil spring, but those skilled in the art will recognize that other types of springs may be utilized. Coil spring 38 coaxially surrounds the shank of bolt 36 and is compressed between yoke 34 and a lower surface of flange 24. The rearward end of the flange 24 terminates in a bracket 40 to which is bolted a tubular cross member 42. A plurality of disc blade scraper assemblies 44 are pivoted to the cross member 42 and biased into engagement with discs 20 by springs 45.

In the operation of the disc harrow 10, the discs 20 are pulled through the earth typically in a direction such as indicated by the arrow 50 as shown in FIG. 2 and at a desired angle with respect to the vertical planes of the discs 20. The passage of the discs 20 through the earth may produce typical working forces which act upon the disc gangs 12 in a direction with a relatively small incline with respect to the horizontal plane and in a direction opposite to the direction of travel of the discs 20. These working forces may act unequally upon opposite ends of the disc gang 12, for example, when one end of the disc gang is deeper in the earth than the other end. These unequal working forces tend to pivot the disc gang 12 in a horizontal plane relative to the frame member 14.

Now, with the applicant's support assemblies 16, the bearing arm 28 extends generally horizontally and rearwardly from the lower end 26 of standard 22 when the disc harrow is in operation. Because of this, and because the pivotal connection at 30 between standard 22 and arm 28 prevents arm 28 from pivoting in a horizontal plane with respect to standard 22 and frame member 14, the gang bolt 18 and the discs 20 are constrained to move substantially only in a vertical direction and are prevented from moving in a horizontal or lateral direction under the influence of the above mentioned unequal working forces. Thus, the pair of applicant's support assemblies 16, spaced apart between the disc gang 12 and the frame member 14, prevents pivoting of the disc gang 12 in a horizontal plane relative to the frame member 14, and maintains the desired angle between the planes of the discs 20 and their direction of travel.

The typical working force acts upon the discs 20 in the direction of arrow 54 viewing FIG. 3. This force tends to pivot arm 28, gang bolt 18 and discs 20 upwards and clockwise relative to the frame member 14 and standard 22 when viewing FIG. 3. However, the bolt 36 may be turned to adjust the compression of spring 38 so that the bias or preload of spring 38 may be maintained sufficiently large to substantially prevent upward pivoting of the arm 28 and discs 20 during normal operation. Thus, the support assembly 16 acts like a rigid member under normal tillage conditions.

However, when one of the discs 20 encounters a rock or other obstruction in the soil, then that disc may be subjected to an obstruction force in a direction with a larger incline with respect to the horizontal plane such as indicated by arrow 60 of FIG. 3. The larger vertical component of the obstruction force overcomes the bias of spring 38, causing arm 28 and disc 20 to pivot clockwise about 30 to raise the disc 20 over the obstruction. In this mode, the spring 38 absorbs and dissipates the energy of the collision between the disc 20 and the obstruction, thus preventing damage to the components of the disc harrow 10.

An understanding of the operation of applicant's support assembly 16 may be aided by a discussion of the "moment arm" concept as it applies to this invention. During normal working operation, the typical working force 54 acts to pivot arm 28 through a moment arm of length A, as shown in FIG. 3. However, during a collision with an obstruction, the more steeply inclined obstruction force 60 acts through a much longer moment arm B. In fact, from viewing FIG. 3, it can be understood that the moment arm through which any force acts upon arm 28 decreases as the angle of that force with respect to the horizontal plane decreases. Conversely, with the typical "C" type spring shown in FIG. 4, the moment arm A', upon which acts the slightly inclined typical working force 54', is larger than the moment arm B', upon which acts the more steeply inclined obstruction force 60'. This is due to the fact that the disc 20' pivots about a pivot point 30' which is located near the upper end of the "C" type spring. In contrast, in applicant's support assembly 16, the disc 20 and the arm 28 pivot about a pivot point 30 located substantially below the level of the frame member 14 and near to the vertical level of the axis of the gang bolt 18. Since the obstruction force also tends to be larger than the typical working force, the resulting moment of force which tends to pivot arm 28 and one of the discs 20 upwards during a collision between that disc and an obstacle is much larger than the moment of force which results during typical operation. Thus, the applicant's support assembly 16 is substantially rigid during typical working operation, but yields as desired when one of the discs 20 encounters an obstacle.