US3706207A

US3706207A - Apparatus for burying a plastic drainage pipe line in the ground

Info

Publication number: US3706207A
Application number: US117506A
Authority: US
Inventors: Werner Cornelius; Friedrich Kaminski
Original assignee: CORNELIUS WERNER KG
Current assignee: CORNELIUS WERNER KG; WERNER CORNELIUS KG TIEF-UND KULTURBAU
Priority date: 1970-02-26
Filing date: 1971-02-22
Publication date: 1972-12-19
Anticipated expiration: 1989-12-19
Also published as: AT319148B; RO57094A; PL74269B1; CS167913B2; ES415989A1; BE763437A; HU167579B; DK137687B; YU33403B; FR2078956A5; DE2008995B2; FI55380B; NL7102655A; ES199318Y; ES199318U; SE390181B; CA933761A; YU42571A; DK137687C; BG26677A3

Abstract

The apparatus comprises a coulter with a guide passage for the pipe extending therein from an opening in the upper part thereof to its rear edge and a nose projecting from the lower section of the coulter front edge. The nose is provided with a roof-like oscillatory edge member sloping upwardly from the nose peak to the coulter front edge. The apparatus suspended at a tractor and engaging the ground with its lower section can be dragged with a smaller tractor output or with higher speeds than similar tools without an oscillatory nose edge member.

Description

United States Patent Cornelius et al.

1 Dec. 119, 1972 Stoffel 172/40 [5 APPARATUS FOR BURYING A 3,538,986 11/1970 PLASTIC DRAINAGE PIPE LINE IN 2,843,068 7/1958 Smith et a]. ..6 1/72.6

THE I 3,386,517 1 6/1968 Kelley ..l72/40 3,575,006 4/1971 Rugroden ..61/72.6 [72] Inventors: Werner Cornelius; Friedrich Kaminski, both of Nordhastedt, Germany primary Examine, |acob Shapiro [73] Assignee: Werner Cornelius KG, Tief-und AtmmeyBeamafl & Beam?!" Kulturbau, Nordhastedt, Germany [22] Filed: Feb. 22, 1971 [57] ABSTRACT The apparatus comprises a coulter with a guide [21] Appl' 117506 passage for the pipe extending therein from an opening in the upper part thereof to its rear edge and a g Application Priority Data nose projecting from the lower section of the coulter Feb. 26, 1970 Germany ..P 20 08 995.6 mm edge The nose is Prfvided with a mof'like Oscil' latory edge member slopmg upwardly from the nose 52 U.S. c1. ..61/72.6, 37/193, 172/40 P to the coulter from edge- The apparatus [51] 1111.c1....' ..E02f 5/02, AOlb 3/64, F161 1/00 Suspended at a tractor and engaging the ground with 58 Field 61 Search ..61/72.6, 72.7, 72.5, 72.1; its lower section can be dragged with a smaller tractor 192/40; 377193 output or with higher speeds than similar tools without an oscillatory nose edge member. [56] References Cited 7 13 Claims, 9 Drawing figures UNITED STATES PATENTS I 3,497,016 2/1970 Ryan ..61/72.6 x

m/ /i/ I; 57 11 l 49 s l 21/ I I PATENTEBMMQW SHEET 1 OF 2 3,706,207

I I I 1 Q Fig. 2 11 12 APPARATUS FOR BURYING A PLASTIC DRAINAGE PIPE LINE IN THE GROUND BACKGROUND OF THE INVENTION The invention relates to an apparatus for burying a drainage line consisting of a finished plastic pipe provided with passage openings, said apparatus comprising a coulter adjustably suspended from a tractor and movable essentially vertically to form a narrow slot-like ditch suited for burying the plastic pipe therein, with a tubular guide passage for the pipe provided in said coulter designed in the shape of an essentially vertically extending smooth plate, said passage leading from the upper side of the coulter to the lower end of its trailing edge, the thickness of the plate of the coulter being only slightly greater than the diameter of the plastic pipe, and a nose with a roof-like edge gradually sloping upwards in a rearward direction projecting from the front side of the coulter in its underground section, the lower sole edge of said nose extending essentially horizontally and merging steadily with the lower edge of the coulter.

The nose with its upwardly-sloping roof-like leading edge and its essentially horizontally extending sole edge is important for the mode of operation of such a coulter. This nose on the one hand takes care that the soil is broken up before the front edge of the coulter and is not pressed away laterally and compacted. In this manner, the soil structure with its many capillaries remains intact beside and above the buried plastic pipe. The more the nose projects forwardly and the smaller the angle of pitch the more will the soil be moved up and the less will the soil be compacted at the sides of the coulter. The preferred angle of pitch with the known coulters of this type is to 70 and is of course dependent on the respective soil.

The nose also fulfills the function of stabilizing the movement of the coulter through the soil on the respectively adjusted level, namely by means of a vertically downwardly directed reaction force resulting from the nose angle of pitch and the moving up 'of the soil in front of the nose which force together with the weight of the coulter presses the coulter downward, i.e. onto that region by which the sole surface of the coulter is supported on the soil. This downwardly directed force must always be a positive one but must not become too great in order to be able to influence the respective level of the coulter by means of moderate additional control forces. Accordingly, with a long projecting nose and a small nose angle of pitch it might happen, dependant on the respective soil, that the reaction force directed downward onto the coulter together with the weight of the coulter becomes so great that the control forces available are no longer sufficient to adjust the submergence of the coulter with a sufficient speed corresponding to the desired drain pipe position.

As a rule, when arranging such a nose at the coulter plate no special surfaces need be provided in order to absorb the downwardly acting reaction forces stemming from the oblique nose surface without the coulter moving further downward under the influence of said downwardly acting forces. In soils having little ability to support loads such as moor or peat it may, however, be recommendable to provide at the coulter an essentially horizontally extending sole or wing surface which is capable of absorbing these reaction forces. This wing surface is, as a rule, but not necessarily, arranged at the lower ends of the coulter and the nose. The dimension of this sole or wing surface is likewise governed above all by the load bearing capacity of the soil.

The result of this is that with soils having a particularly low load bearing capacity it would be possible not to provide the coulter at all with a projecting nose but only equip it with an essentially horizontally extending sole plate of a greater or smaller dimension. The invention starts from the assumption that also, in such cases, a projecting nose has to be arranged in order to loosen the soil in front of the coulter and break it up. Under certain circumstances then, the sole surface may be designed to be a bit greater, in order to absorb the additionally resulting downwardly directed reaction forces In such a case it might then be recommendable to design the projecting nose to be a little narrower than the coulter itself and, if desired or required, impart to the roof-like edge of the projecting nose a slightly steeper angle of pitch. With such types of apparatus it is possible to bury a drainpipe continuously at a speed of about 2500 to 3500 m/h. This is applicable in particular when the respective depth of the coulter and along with it the slope of the slot-like ditch drawn by the coulter are checked with the aid of a th eodolite or a similar angle measuring device from a stationary point which then transmits the respectively required depth correction to the coulter via a remote control.

The known apparatuses of this type, however, show advantages in many respects. Admittedly, it is possible with the aid of heavy caterpillar, tractors to bury a drainpipe of about mm diameter at the indicated high speeds. But if the diameter of the drainpipe exceeds the indicated dimension excessively the required pulling forces can only be applied with difficulty.

In a corresponding manner it would also be desirable, even with difficult soils, to control the burying speeds indicated and to increase them, respectively. But here as well the driving force is limited.

Finally, it has been found to be more and more desirable with the laying of such drainage lines if possible to loosen the soil more effectively than before, in particular, above the drainage line thus increasing the draining effect brought about by the drainage pipe.

The invention is concerned with the problem of improving the known devices of this type in such a manner that the necessary pulling force is reduced and the soil is better loosened.

SUMMARY OF THE INVENTION The problem is solved in accordance with the invention in that the roof-like sloping edge of the nose projecting from the coulter is adapted to be oscillated by means of an oscillation generator.

Accordingly, the point is for the coulter proper to be kept invariably in its position thus being capable of securing the steady onward movement of the coulter through the soil of the desired level. Owing to the fact that the roof-like sloping edge of the nose is oscillated there results an improved loosening of the soil and an essential reduction in the pulling force required to move the coulter onward through the soil. It is possible in this manner with constant pulling force either to increase the diameter of the drainpipe or, with constant drainpipe, diameter run the apparatus at an increased travel rate or, with a constant travel rate run the apparatus with a lower machine output and with a smaller and less powered tractor, respectively.

It is recommendable that the oscillatory movements of the roof-like sloping edge of the projecting nose take place in a vertical plane.

In addition, it may be recommendable to oscillate also the side walls of the projecting nose.

With an embodiment of the invention, the roof-like edge and the side walls of the projecting nose are connected with each other and may be oscillated about a horizontal axis. This axis is suitably disposed near the front point of the nose with the roof-like sloping edge of the nose being designed as a one-armed lever.

The axis may also'be arranged approximately in the center of the oscillating member whereby the driving forces may be reduced, because the oscillating member is designed like a balance. A wearing plate is arranged on the oscillating member which may be selected to be a wider dimension when pipes of larger diameters are laid.

For normal soils it is recommendable to have the rigid nose projecting from the front edge of the coulter over a distance approximately equal to the submergence of the coulter.

With a non-oscillating nose, an angle of pitch of about 45 has proved to be suitable as a rule. If, however, in accordance with the present invention one arranges the roof-like sloping edge and, if desired or required, the side face of the nose in a manner to be capable of oscillation, the angle of pitch of the nose can be reduced so as not to move the soil forwardly but move it upwardly. To carry out the invention a nose angle of approximately to 40 has proved to be especially suitable.

In accordance with the invention, the oscillation generator is driven by means of a motor arranged on the upper part of the coulter above its submergence section. This motor may be adapted to be driven from the tractor by means of a journal shaft, for example, drivingly connected with the drive motor of the tractor. It may also be provided as an internal combustion, hydraulic or electric motor being an independent driving aggregate on the tractor.

With a suitable embodiment of the invention the approximately vertical front edge of the coulter is provided with a serrated profiling which may be moved vertically up and down. Suitably, the serrated profiling is arranged on a rod which either is interposed between the oscillation generator and the oscillatory'roof-like edge of the nose or is connected with the oscillatory edge plate by means of an axle and is moved by the plate.

In another embodiment of the invention the pushrod driving the oscillatory edge plate is arranged in the rear of the coulter where it is better protected from lateral pressure. An additional rod with serrated teeth may then be supported along the front edge of the coulter. It is driven by the oscillatory edge plate via an axle bolt. This connection may be loosened in a simple manner so that the serrated rod may be removed if soils are worked in which the rod is not needed or it may be replace by a new one.

4 BRIEF DESCRIPTION OF THE DRAWING Further improvements and embodiments of the invention will be explained in further detail by way of the enclosed drawing.

In the drawing,

FIG. 1 shows a view of a known arrangement with a tractor and coulter to bury a drainage line consisting of an endless plastic pipe,

FIG. 2 shows a sectional view of the projecting nose of the coulter on an enlarged scale, taken on line IlIl of FIG. 1,

FIG. 3 shows a sectional view taken on line III-III of FIG. 1 likewise on an enlarged scale,

FIG. 4 shows a partially sectional diagrammatic view ofa coulter designed in accordance with the invention,

FIG. 5 shows a likewise partially sectional diagrammatic view of another embodiment of the coulter in accordance with the invention,

FIG. 6 shows a likewise partially sectional view of a third embodiment of a coulter designed in accordance with the invention,

FIG. 7 shows a sectional view taken on line VIIVII OF FIG. 6, and

FIG. 8 shows a sectional view taken on line VIII- VIII of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with FIGS. 1 to 3 there is a coulter suspended from a tractor I said coulter being generally referenced 2. It consists of a coulter part 3 with a passage 4 arranged along the front edge thereof which functions to supply a flexible pipe to be buried, especially a drainpipe consisting of plastic material. The flexible line is supplied to the upper end 5 of the passage 4 in some manner not shown in any more detail and leaves the coulter 2 at the rearwardly pointing opening 6. The coulter 3 is moved through the soil by means of the tractor l in the direction of the arrow I thereby ploughing a ditch. A certain supply of the plastic pipe to be laid may be supported on the tractor l but may also be supported on a special vehicle provided with an independent drive.

The coulter 2 is provided with sole wings 7 on its lower end the rear edge 8 of which terminates approximately flush with the exit opening 6 of the channel 4. The sole wings in this embodiment from an obtuse angle and meet the lower point of the roof-like sloping edge 11 to form a peak 9 pointing forwardly in the direction of movement. In order to illustrate the size attention is drawn to the fact that the drainpipe has an outer diameter of about 50 mm and the drainpipe passage is only slightly wider than the outer diameter of the drainpipe. The rear edge 8 of the sole wings 7 may then have a width of 30 mm, for example, while the length of the sole wings 7, i.e. its extension from the rear edge 8 to the point 9, may be 700 mm long. These dimensions, however, are only made in order to explain an embodiment and may change within wide limits.

A nose 10 is provided between the front edge of the passage 4 for the drainpipe and the sole wings 7 the sloping roof edge 10 of which extends upwardly from the peak 9 of the nose. The oblique arrangement of the front edge 11 is important for the depth adjustment of the coulter.

The front edge 11 of the nose is pointed in the form of a wedge as will be seen at 12, however, including an angle of approximately 45. Thus, the nose con tributes to stabilize the coulter longitudinally but does not or only very little contribute to compact the displaced soil. That is important because the soil structure near the buried drainage pipe is to be changed or even disadvantageously influenced as little as possible.

The coulter part 3 which is arranged behind the drainpipe passage 4 not only stiffens the passage 4 but also adds to the longitudinal stability of the coulter by its portion extending into the soil.

The two links 16, 17 of a parallelogram guide are pivotally connected to a stand 13 of the tractor, said parallelogram guide being generally referenced 18. The two free ends of this parallelogram guide are connected by means of an intermediate carrier 19 which is pivotally engaging at the links 16, 17 via

journals

20 and 21.

The coulter 2 is fastened to a frame 22 extending essentially normally with respect to the longitudinal extension of the coulter 2. Fastening is adjustably provided by means of screws and nuts 23 so that the vertical position of the coulter may be changed by adjustment of its position within the frame 22 into the position of transport for example. After the coulter 2 has been connected with the frame 22 the two parts form a rigid assembly.

The gravity center of the tractor is referenced 24. A I

perpendicular line 26 drawn from this gravity center 24 to the ground 25 hits the ground at a point 27. Two guide tracks 28 and 29 are provided in the intermediate 7 carrier 19 in the form of two circular grooves. The circle center of the circular paths of these two grooves 28, 29 is approximately in point 27. The two grooves 28 and 29 are separated from each other by a web 30 of greater or lesser width in order to increase the stiffness of the intermediate carrier 19. But the two grooves 28 and 29 may also be combined to form one single groove. Two rollers 31 and 32 are rotatably supported on the frame 22, and roller 31 is designated as a drive roller and the other roller 32 as a counter-acting or supporting roller for reasons to be explained herebelow. The drive roller 31 engages the guide track 29 which therefore is also called the driving guide track while the counteracting or supporting roller 32 engages the guide path 28 which accordingly may also be called a supporting or counteracting guide track. The slope of the track 29 with respect to the vertical direction of movement is smaller than the slope of track 28 with respect to this direction.

The lower link 17 is bipartite. One link portion 17 is provided with a right-hand thread 33 and the other link portion 34 is provided with a left-hand thread 34 which threads 33, 34 are cooperating in a well-known manner with a clamping nut 35. The link 17 thus may be shortened and lengthened by rotation of the clamping nut 35.

The parallelogram guide 18 can be adjusted by means of the servo motor 36 which is designed in particular as a hydraulic servo motor. It is supported on the one side on the stand 13 near the pivot axis 15 and engages on the other side at the link 16 by means of a journal 37.

The rollers 31, 32, the guide tracks 28, 29, the intermediate carrier 19 and the parallelogram guide 18 are arranged symmetrically on both sides of the longitudinal center plane of the tractor 1, the frame 22 being U-shaped, for example.

By actuation of the clamping screw 35, the position of the intermediate carrier 19 and that of the coulter may be changed. With this it is possible to impart to the sole wings 7 of the coulter, a slight inclination towards the horizontal in the way of an elevator of an aircraft.

When moving the tractor 1 in the direction of arrow 1 in FIG. 1, a pull is exerted on the coulter unit comprising the parts 2 and 22, via the drive roll 31 in the driving guide track 29 of the parallelogram guide 18.

Owing to the weight of the coulter and the digging force generated by the oblique front edge of the nose 10 the coulter is pressed downward. This downwardly directed force is intercepted by the sole wings 7 pressed on the bottom of the ditch.

The tilting movements of the tractor 1 aboutpoint 27 are essentially balanced by sliding of the rollersin the guide tracks 28, 29.

Disturbances of the uniform horizontal sliding movement of the sole wings 7 are intercepted by the supporting roller 32 in the supporting track 28.

The adjustment of the center point of the circularsectional guide tracks 28 and 29 to the tilting point 27 of the tractor is obtained by rotation of the clamping nut 35 thereby adjusting the inclination of the intermediate carrier 19.

The digging depth of the coulter 2, however, may be changed also by height adjustment of the parallelogram guide by means of the servo motor 36, changing thereby the angle of pitch of the coulter.

Provisions may also be made for the stand 13 to be pivotable on the tractor in a manner not shown in more detail about an axle arranged near the tractor lower end. In this connection, a hydraulic servo motor 38 is provided which controls the position of stand 13 and with it also the position of the intermediate carrier 19 dependant on the vertical position. In FIGS. 1, 4, 5 and 6 the coulter 2 is shown in its vertical position so that the sole wings 7 are disposed horizontally. It may be recommendable to control the coulter 2 and the sole wings 7 with the aid of servo motor 38 dependant on the vertical in such a manner that the sole wings 7 and the lower edge of the coulter, respectively, always have a certain positive or negative inclination of some angular degrees with respect to the horizontal, thereby facilitating the automatic guidance of the coulter along a predetermined inclination.

According to FIG. 4, the coulter 39 is provided with sole wings 40 which carry a pointed shoe 42 at their peak 41. This pointed shoe 42 may become so small that the wear plate coincides with the point and overlaps the shoe.

The oblique roof-like edge 43 of the shoe 42 is extended further in an oscillatory member 44 having a replaceable wear plate 60 screwed thereto and being supported pivotally about the axis 45. The oscillation drive of the oscillatory member 44 is effected by means of an eccentric 46, which is supported in the upper portion of the coulter 39. Drive of the eccentric 46 is effected by means of an electric or hydraulic motor 57 which is likewise supported on the upper portion of the coulter.

ported to perform oscillations about an axis 48 which is arranged near the peak 41 of the nose. Thus, the oscillatory member 47 is designed as a one-armed lever. The pushrod 50 engages at the other end of this lever in the axis 49, said pushrod being vertically moved up and down by means of an eccentric drive 46. Teeth 51 are mounted on the pushrod front edge in order to cut the soil.

FIG. 6 shows a construction in which the pushrod 59 is arranged in the rear part of the hollow member 39 of the coulter. A second rod 61 is connected with the oscillatory member 44 by means of an axle 62. It is retained in its position by a sliding member 63. Serrated teeth 51 are arranged on the front edge of the rod FIG. 7 shows a sectional view taken on line VII-VII across the coulter nose of FIG. 6. A wear plate 60 is replaceably fastened on the oscillatory member 44. The oscillatory member is designed as a wedge 64 at the bottom in order to push away the soil placing itself therebetween during the up and down movements. Also the nose member 65 disposed therebelow is shaped like a wedge in order to avoid cloggings. The sole wings 40 are arranged below the nose member.

FIG. 8 shows a sectional view taken on line VIII- VIII across the coulter of FIG. 6.

The pushrod 59 is arranged in a protected place within the coulter 39; the plastic drain pipe 66 to be buried is guided through the pipe channel 4. The additional rod 61 carrying the serrated teeth 51 is arranged in front of the coulter 39. As this latter rod is subjected to considerable wear, it may be removed simply by loosening the connection at 62 in FIG. 6.

It will be seen that the coulter only draws a narrow slot-like ditch at the bottom of which the plastic pipe is placed. The slot-like ditch is so narrow that as a rule it will be filled again by itself with the soil falling back into the ditch. This is also enhanced by the fact that the soil is loosened in front of the coulter by means of the shaking or oscillating nose. Under certain circumstances it may be recommendable to provide scrapper sheet members at the rear edge of the coulter to enhance the filling-up of the slot-shaped ditch by the soil.

In the embodiment shown by way of example in FIG. 9 the pointed shoe 42 of FIGS. 4, and 6 is clipped and the wear plate 60 simultaneously forms the peak and overlaps the shoe. As the axis 45 is near the peak the front portion of the oscillatory plate will oscillate at the same frequency although with a reduced amplitude. In this manner there results an especially good loosening effect in that also the soil in the immediate neighborhood of the drainpipe to be buried is broken up.

The plastic pipe may be surrounded either entirely or partly by a filter material.

The submergence depth of the coulter in the soil is not constant, but the bottom of the ditch drawn by the coulter has a certain angle of inclination so that the 8 ground water seeping through its passage openings into the pipe may drain off pressureless. This angle of inclination is very small (in many regions only a head of 0.1 percent is available) but it must be maintained accurately so that the water is not accumulated and may drain off.

Frequently, with the aid of the invention, a wheeled tractor may be used instead of the illustrated tread type tractor. The wheeled tractor is much easier to maneuver than a tread type tractor when the place where to employ the coulter is changed; this may lead to a considerable reduction in the costs for laying the drainpipes. The wear plate which is provided to be replaceable in accordance with the invention may be selected to have a width exceeding that of the coulter when drain pipes of larger diameters are to be laid.

What we claim is: g

1. Apparatus for burying a conduit in the earth comprising, in combination, a movable coulter support, a coulter vertically suspended from said support having an upper region, a front edge, a rear edge, and abottom edge, a nose mounted on said coulter bottom edge projecting forwardly beyond said front edge and having a forward end, an oscillating edge member movably mounted upon said coulter above said nose and having a first end disposed adjacent said nose forward end and a second end disposed rearwardly with respect to the direction of movement of said coulter, said edge member being obliquely disposed to the horizontal inclining upwardly from said first end to said second end, and oscillating drive means connected to said edge member for producing oscillation thereof.

2. Apparatus in accordance with claim 1, wherein said coulter defines a plane and the oscillation movement of said edge member is in said coulter plane.

3. Apparatus in accordance with claim 1, wherein said nose projects beyond said coulter front edge a distance approximately equal to the submergence depth of the coulter bottom edge.

4. Apparatus in accordance with claim 1, wherein said oscillating drive means includes a motor mounted on said upper region of said coulter.

5. In an apparatus as in claim 1, an elongated serrated member movably mounted upon said coulter front edge adjacent said edge member for vertical movement on said coulter, said oscillating drive means being connected to said serrated member.

6. Apparatus in accordance with claim 5, wherein said serrated member is formed as a rod connecting said oscillating drive means with said edge member.

7. Apparatus in accordance with claim 5, wherein said serrated member is formed as a first rod driven by said drive means and said edge member is connected with said drive means by a second rod.

8. In an apparatus as in claim 1, pivot means mounting said edge member upon said coulter for pivotal movement about an axis transverse to the length of said nose whereby said edge member oscillates in a substantially vertical plane substantially parallel to the direction of movement of said coulter.

9. Apparatus as in claim 8 wherein said pivot means is located adjacent said nose forward end and said edge member constitutes a lever. i

10. Apparatus in accordance with claim 8, wherein said edge member comprises a two-armed lever.

9 10 11. Apparatus in accordance with claim 10, wherein produce lever oscillation s oi small amplitude at said the axis of oscillation of said two-armed lever is first end. disposed approximately in the center thereOf- 13, Apparatus in accordance with claim 8, wherein 12. Apparatus as in claim 10 wherein said edge member first end projects ahead of said nose in the S direction of coulter movement and said pivot means is disposed adjacent to, but spaced from, said first end to said edge member is inclined towards the horizontal by to 40.

Claims

1. Apparatus for burying a conduit in the earth comprising, in combination, a movable coulter support, a coulter vertically suspended from said support having an upper region, a front edge, a rear edge, and a bottom edge, a nose mounted on said coulter bottom edge projecting forwardly beyond said front edge and having a forward end, an oscillating edge member movably mounted upon said coulter above said nose and having a first end disposed adjacent said nose forward end and a second end disposed rearwardly with respect to the direction of movement of said coulter, said edge member being obliquely disposed to the horizontal inclining upwardly from said first end to said second end, and oscillating drive means connected to said edge member for producing oscillation thereof.

9. Apparatus as in claim 8 wherein said pivot means is located adjacent said nose forward end and said edge member constitutes a lever.

11. Apparatus in accordance with claim 10, wherein the axis of oscillation of said two-armed lever is disposed approximately in the center thereof.

12. Apparatus as in claim 10 wherein said edge member first end projects ahead of said nose in the direction of coulter movement and said pivot means is disposed adjacent to, but spaced from, said first end to produce lever oscillations of small amplitude at said first end.

13. Apparatus in accordance with clAim 8, wherein said edge member is inclined towards the horizontal by 20* to 40* .