Earth working – Overload shifting – Against spring return device
Reexamination Certificate
1999-09-10
2001-06-26
Batson, Victor (Department: 3671)
Earth working
Overload shifting
Against spring return device
C172S708000
Reexamination Certificate
active
06250397
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates generally to agricultural implements and, more specifically, to a spring trip standard for tillage implements.
2) Related Art
Spring trip standards typically include a mounting bracket attached to rectangular toolbar and extending upwardly and rearwardly to a downwardly and forwardly directed spring abutment surface. A spring is compressed between the abutment surface and an upwardly directed spring abutment surface on a member pivotally connected to the lower portion of the bracket, and a tool supporting shank is fixed to the member. A tension link assembly extends from the shank supporting member through the spring and through an aperture in the spring abutment surface on the bracket to adjust the preloading of the spring and vary the vertical position of the tool connected to the shank. Such an assembly is shown by way of example in U.S. Pat. No. 3,700,039 entitled SPRING TRIP SHANK ASSEMBLY. This type of shank assembly provides good trip force characteristics but has numerous parts and is expensive and time-consuming to assemble and repair. Previously available assemblies, particularly those with numerous tension link or spring support components such as pins, straps, spacers and washers, typically require extensive instructions for assembly and disassembly.
In some shank assemblies, the tension link reduces forces on the pivot area in the at rest position, thereby introducing some looseness in the pivot joints which often is perceived as a quality disadvantage and which causes the tool to have some lateral shift during operation. Often the precompression of the spring when the tool is in the normal operating position is not sufficient to prevent some continual tripping action. The portion of the tension link extending through the aperture is subject to wear as a result of such tripping action. In spring trip shank assemblies of the type shown in U.S. Pat. No. 4,520,878 the bottom of the coil spring rests on a seat which can swivel to maintain the lower face of the spring substantially normal to the longitudinal axis of the spring and thereby reduce spring buckling forces. In another type of assembly shown in U.S. Pat. No. 3,700,039, the lower end of the coil spring is free to rock on a clamp bolt to remain normal to the centerline of the spring. These devices introduce additional wear components into the assembly.
In our commonly assigned and copending application Ser. No. 09/216,270 filed Dec. 18, 1998 and entitled SPRING TRIP STANDARD, we describe a spring trip arrangement which does not require a tension link. In commonly assigned application Ser. No. 09/325,454 filed Jun. 3, 1999 and entitled SPRING TRIP STANDARD HAVING REDUCED SPRING BUCKLING FORCES, spring seat structure is described for providing generally perpendicular alignment of the lowermost coil of the spring relative to the centerline of the coil spring in both the field-working and the tripped positions so that spring buckling and spring fatigue caused by buckling are reduced. Upstop limit for the shank is provided by the spring when the spring coils stack against each other. When a shank trips upwardly over a large obstacle to the maximum tripped position, the force can be so great on the fully compressed spring, even when properly aligned between the spring abutment surfaces on the assembly, that the spring coils slip past one another causing permanent deformation of the spring and loss of normal spring characteristics.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved spring trip assembly for an implement. It is a further object to provide such an assembly which overcomes most or all of the aforementioned problems.
It is a further object of the present invention to provide an improved spring trip assembly which has fewer parts and is lower in cost than most previously available shank assemblies and which protects the spring against damaging forces when the shank trips to the limit position over obstacles. It is another object to provide such an assembly which protects the spring against permanent deformation when heavy trip forces are encountered.
It is still another object of the invention to provide an improved spring trip shank assembly wherein the spring is protected against permanent deformation. It is another object to provide such an assembly which is easier to assemble and disassemble than at least most previously available shank assemblies.
It is yet a further object of the present invention to provide an improved spring trip standard assembly having a loaded pivot area for perceived improvement in stability and tool tracking compared to many previously available assemblies, the assembly including a positive upstop to protect the spring against deformation. It is another object to provide such an assembly which includes a positive downstop. It is another object to provide such an assembly which has fewer parts and fewer wear areas than at least most previously available spring trip assemblies.
A spring trip standard for a tillage implement includes a coil spring compressed between an upper spring-abutting surface on the mounting bracket and a lower spring abutment surface on a casting which is connected by a transverse pivot to the mounting bracket. A tool supporting shank is bolted to the casting and biased downwardly into a ground working position by the spring. The casting includes a first integral stop extending forwardly from the pivot. The stop contacts the bottom of the bracket when the shank is in the ground working position so that a tension link between the bracket and casting is eliminated. A relatively high trip force prevents unwanted tripping of the shank and prevents looseness in the shank so the desired fore-and-aft and lateral position of the tool is maintained for maximum efficiency. The casting includes a spring receiving projection to help maintain the bottom of the spring in position. The projection is slotted to receive a simple compression tool for compressing the spring to disassemble and reassemble the standard. Wear only occurs in the components of a relatively inexpensive bushing and sleeve assembly in the pivot, and these components can be easily replaced using the tool to compress the spring and remove the loading from the pivot without complete disassembly of the unit. If complete disassembly is required for any reason, the tool permits complete relaxation of the spring. The shank assembly has a minimal number of components and is relatively inexpensive and easy to assemble.
The standard also includes a second stop to limit upward pivoting to a maximum tripped position wherein the spring is in or approaches a fully compressed condition but is not forced into an overly compressed condition wherein spring deformation occurs. In one embodiment, the casting includes opposite sides defining shoulders which abut the rear edges of the rearwardly opening, channel-shaped mounting bracket when the maximum tripped position is reached. The extended contact between the shoulders and the rear edges provides a strong, positive stop. Both the downstop and upstop functions are provided by a single casting. In another embodiment, a projection extending upwardly from the rear of the shank support contacts the mounting tube on the implement to limit upward pivoting of the support so the spring is not forced into an overly compressed condition.
The casting includes a spring abutment surface having a first portion which extends generally perpendicular to the spring axis when the shank is stopped in the normal working position to support the lowermost end of the spring. The opposite side of the spring abutment surface is angled relative to the first portion and abuts the lowermost coil of the compressed spring coils in the tripped position to maintain the spring in a generally non-buckling state. A generally perpendicular alignment of the lower coil relative to the centerline of the coil spring is maintained in both the field-working and tripped posit
Hook Richard Wayne
Zaun Richard David
Batson Victor
Deere & Company
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