Tool Support

The present invention relates to groundworking farm implements having tools which trip as obstructions are encountered and automatically reset upon clearing the obstruction.

Groundworking implements having hydraulic or spring trip mechanisms for protecting tools from damage as obstructions are encountered are well known in the art. A typical implement is an automatic reset plow which includes a mechanism permitting the plow bottom to rotate and rise with respect to the main frame when resistance is encountered and, when the obstacle is passed, automatically resetting or restoring the groundworking tool or plow bottom to the operating position. Certain types of plows support the plow bottom and its standard for floating movement about a pivotal connection with the frame. This type of arrangement causes the angle of attack of the plow bottom to increase as it floats. In such an arrangement the plow floats or raises in an arc about its pivotal connection with the frame. Still other plow bottom support arrangements provide for hydraulically controlled trip mechanisms which permit tripping rotation of the bottom about its supporting pivot on the standard. (See for example, U.S. Pat. No. 3,565,180 to Arnold et al, issued Feb. 23, 1971. In this arrangement, the plow is able to float about its pivotal connection with the frame or alternately trip and rotate about its pivotal connection with the standard when obstacles are encountered. This design has met with commerical success and its a high quality trip mechanism. However, it is a comparatively expensive arrangement and does have the inherent problems associated with hydraulic systems such as leakage and plumbing problems.

There is herein provided an earthworking tool support means which permits floating movement of the tool without significant changes in its earth penetrating angle of attack, and there is further provided a biasing means in the form of a spring-loaded mechanism for yieldably resisting the vertical floating movement of the tool and the rotational movement of the tool about its pivotal connection with the standard, and for also restoring the tool to an earth penetrating configuration and then back to working position after it has been tripped.

Supporting the earthworking tool for generally vertical floating movement is a four bar linkage having two of its opposite links of approximately the same length. This linkage configuration ensures a nearly straight up and down floating movement of the plow bottom so that the tool angle of attack remains within the acceptable ground penetrating configuration as it floats. This four bar support linkage further aids in permitting the use of comparatively low force biasing or spring means as compared to that required for a single pivot support. Coupled with the four bar linkage is the spring means which acts to urge the four bar linkage down.

To resist pivotal rotation of the bottom about its supporting connection with the first four bar linkage, the spring means is also connected to the plow bottom through a second four bar linkage which has a common link with the first four bar linkage. This second four bar linkage includes toggle linkage coupled with the biasing means, which permits rotation of the bottom upon encountering forces which exceed a threshhold value, and which acts to urge the bottom back to its operational position after being tripped.

The second four bar linkage further provides a lever rigid with the tool to enable the spring to counteract the large forces encountered during earthworking operation. The toggle linkage enables the springs to yieldably resist the high obstruction forces when necessary, but immediately collapse and yield when those forces exceed a threshhold value.

With this novel biasing and tripping arrangement, the tool is able to float essentially vertically during operation in order to pass over, for example, the upper surfaces of obstacles such as embedded stones. The tool may, however, yieldably rotate or trip to clear blunt obstacles. Most importantly, however, the tool may also release from and clear obstacles that the tool point hooks under.

FIG. 1 is a side view of a plow bottom and its support or suspension mechanism utilized in mounting it on a plow frame.

FIG. 2 is a plan view of the suspension mechanism shown in FIG. 1.

FIG. 3 is an enlarged rear view of the suspension mechanism.

FIGS. 4, 5 and 6 are side views showing the plow bottom as it would move when the point of the plow bottom moves from under an obstruction and also showing the action of the tripping mechanism as the plow bottom trips and then resets prior to reentry into the ground.

FIG. 7 shows the plow bottom as it would float and move over a surface obstacle, the obstacle not being of the type which would cause a complete tripping of the supporting mechanism.

FIG. 8 shows a plow bottom as it trips and moves over an obstacle.

FIG. 1 illustrates the implement or plow in its operating configuration.

The plow has a C-shaped frame member 10 constructed so as to clamp to a conventional plow frame not shown.

Pivotally connected to the frame 10 is the four bar linkage with one link thereof being the vertically disposed rear portion of the frame member 10. Upper and lower pivots 11 and 12 support the other three rigid links 13, 14 and 15 for movement through a vertical plane between a lowered and raised position. The link 10 and coupler link 15 are of approximate equal length and generally parallel. Floating movement of the pivotal connection supporting the standard and tool is generally vertical in nature. In this way the angle of attack of the plow bottom is substantially the same as it floats over obstacles in the ground and returns to a full down working position or depth.

Yieldably urging the four bar linkage means toward its lowered position and illustrated in FIGS. 1 and 2 is the biasing means pivotally carried by the support frame 10. The biasing means includes a pair of transversely spaced horizontally disposed springs, such as at 18, mounted on separate and parallel eye bolts 16 and 17 which in turn are pivotally secured by respective pins to the support frame member 10 for swinging vertical movement. As is best illustrated in FIG. 2, each eye bolt has a nut 19 including a washer-type enlarged surface secured to the rear end thereof. A spring 18 surrounds each eye bolt and has one of its ends abutting the flat washer portion of the nut 19. A C-shaped elongated can structure 41 encloses the springs 18 and helps to maintain alignment. Secured to the forward end of the can 41 is an upstanding plate member 42 having the openings through which the eye bolts slidably pass. It is between the surface of washer 19 and this flat plate member 42 of the can which the opposite ends of the springs 18 abut.

Joining the linkage with the springs 18 is a lever 20. The lever 20 is pivotally coupled by pin 21 to the four bar linkage and by pin 22 to plates, shown only in dotted representation in FIG. 2, welded to the can between the springs 18. Accordingly, as the plow and consequently the four bar linkage are raised, the pin 22 is moved away from the frame member 10 and the can is shifted along the rods 16 and 17 thereby compressing the springs 18 that are mounted under compression between the flat washers 19 and the plate member 42. The springs 18 would thereby urge the four bar linkage towards its working position. This arrangement permits the linkage and plow to "float" or vertically move between the positions illustrated by the line AB of the envelope ABCD of FIG. 1 during operation. Upon encountering dome-like rocks or abnormal draft conditions, the linkage will raise yet be yieldably urged towards its lowered position. As is evident from FIGS. 1 and 7, the angle of attack of the plow point changes little as it floats.

The biasing means further acts through the lever 20 to maintain the plow in its ground penetrating configuration, yet to yieldably resist rotational movement of the plow away therefrom and to urge the plow towards its ground penetrating configuration after it has been tripped or rotated.

To maintain the plow in its operating configuration yet permit vertical movement of the linkage, a further coupling between the lever means and plow is provided. This coupling permits rotational movement of the plow as excessive draft forces are encountered, but prevents rotation otherwise. Included in this coupling is a second lever 30 which is rigid with the plow standard 23. The standard 23 and lever portion 30 are rotatably coupled by pin 26 to the lower end of a toggle link 25. The standard 23 and its lever portion 30 also are pivotally connected at 24 to the lower end of link 15 and the rear end of link 14. The coupling further includes a toggle linkage composed of an extension of the first lever 20 and the link 25 and having a toggle joint or pivot 27 therebetween. It should be noted at this point that while each of these links and levers are referred to as singular members, that the preferred embodiment (see FIG. 3) actually often utilizes two parallel or identical members to form the respective link or lever in order to provide a more dependable structure. Collectively the links 20, 25, the upper portion 30 of the plow standard and the coupler link 15 of the first four bar linkage form a second four bar linkage that yields to permit the plow standard 23 to swing about pivot 24. The lower toggle link 25 includes an abutment surface 28 engageable with a toggle stop 29 carried by the upper link or lever 20. As is clearly apparent in FIG. 1, the springs 18 normally hold the surface stop 29 against abutment 28. In the normal plowing operation, this toggle joint will be uncollapsed. The draft forces encountered by the plow will act through lower toggle link 25 to create a counterclockwise moment about pin 21. Offsetting this moment about pin 21 will be a clockwise moment generated by the biasing means 18 urging the lever 20 clockwise. As extremely large draft forces acting on the plow occurs, as for example would occur when the plow bottom snags under a stone, the counterclockwise moment will be increased until it exceeds the clockwise moment of the spring and the toggle joint will then collapse (see FIG. 4), permitting the plow to rotate about its pivotal connection 24 with the linkage 10, 13, 14 and 15.

The present invention provides through its toggle linkage for the forces that are encountered by the plow bottom to be transmitted along a line indicated at F.sub.1 (FIG. 1) which passes closely adjacent the axis of pin 21 and consequently has a short moment arm A.sub.1. The spring biasing means having a force F.sub.2 and countering the force F.sub.1 acts through the much longer moment arm A.sub.2 to oppose those forces.

When the plow operates at working depth, major changes in draft forces will cause the plow to "float" within the vertical range defined by points A and B on the envelope illustrated in FIG. 1. These draft forces are for the most part horizontal and are opposed by the biasing means acting through the toggle links to prevent rotation of the plow. Since these draft forces are normally well below that threshhold value required to collapse the toggle links and rotate the plow, only minor "floating" action of the first four bar linkage 10, 13, 14 and 15 occurs. By virtue of its structural configuration, the four bar linkage permits essentially vertical movement of the plow, but with little horizontal movement. Thus, the biasing force opposing vertical movement of the linkage can sufficiently be met by the spring means employed. Occasionally, minor obstacles will be encountered similar to those illustrated in FIG. 7. To clear these obstacles, the plow need not necessarily be rotated or tripped, but can simply float with the linkage up and over them with no interruption in plowing.

Infrequently, however, significant obstacles are encountered which can severely damage or ruin a plow. One example would be the ledge-type rocks prevalent in eastern Pennsylvania and as shown in FIG. 8. With the present device, the plow will release from even this type of obstruction as the plow rotates and raises to unhook the point (see FIGS. 4-6). As this type of obstacle is encountered, the present plow point will become hooked beneath the rock and then begin to rotate (see FIG. 4) as the forces cause the toggle joint to collapse. To clear the rocks, the bottom can rotate so that the point follows a path above or on curve AD shown in FIG. 1. As the plow continues to advance, the bottom rotation about pin 24 will stop as the forward end or edge 35 of the lever portion 30 of the standard 23 abuts a stop 36 carried by the lower link 14. At this point, the standard becomes rigid with link 14 and rotation of the bottom is about point 12. Rotation of the plow now is about a longer radius and movement of the plow is more nearly upwardly as the linkage is forced towards a raised position. This can clearly be seen by comparing the plow positions in FIGS. 4 and 5 and the portion DEC of the envelope in FIG. 1.

Reviewing FIGS. 4 and 5, it is clear that extensions 13E, 14E of the links 13, 14 converge toward one another and toward convergence points C.sub.1 and C.sub.2 respectively, forwardly of the frame portion 10. Referring first to FIG. 4, it becomes apparent that the force F.sub.2 created by springs 18 passes beneath the point of convergence of the links 13, 14 by a distance R.sub.1. Referring then to FIG. 5, it becomes apparent that the force F.sub.2 created by the springs 18 passes forwardly of the point of convergence of the links 13, 14 by a distance R.sub.2. Therefore, after the point crosses into the area EGC, some lift is provided to the bottom and linkage by the springs since the line of force created by the springs passes from beneath the convergence point of links 13 and 14 to above that point. In this way the resultant moment acting on the plow linkage changes from a counterclockwise moment urging the plow linkage downward to a clockwise movement urging the linkage and bottom upward. The four bar linkage 10, 13, 14, 15, therefore, is utilized to continuously reposition the convergence point of the link extensions 13E, 14E in a manner that the spring force can best be utilized to position the plow as well as counteract the draft loads of the ground or buried objects against the plow bottoms.

As the plow bottom clears the obstacle, the biasing means will act on lever 20 to reset the toggle linkage and hence the plow bottom as illustrated in FIG. 6. In this illustrated position, the four bar linkage 10, 13, 14 and 15 is in its fully lifted position and the link 14 is up against a stop 40 provided on the frame. As the springs 18 extend to reset the toggle links 20 and 25, edge 28 will come into contact with stop 29 to reposition the plow to its proper angle of attack. The springs 18 are then in a position to urge the plow back into ground contact which, aided by the gravitation force on the plow, makes for a fast return to plowing position.

While any particular dimensioning of the mounting structure can be adapted, the preferred embodiment has been provided with dimensions which permit the plow bottom to clear normal obstacles in a field. Movement of the plow point A as it floats or rotates over an obstacle can follow any path on or within the envelope illustrated in FIG. 1. Minor changes to that envelope can be made by adjusting the structural dimensions as desired without departing from the advantages provided by the present invention.