DEVICE AT A PLOUGH

Device at a plough

This invention relates to a device at a plough compris¬ ing a plurality of plough bodies mounted vertically ad¬ justably on the plough frame obliquely one behind the other.

One disadvantage of known^"multi-share ploughs of the aforesaid kind is that, like the plough bodies also the ridge ends formed after the plough has been lowered in¬ to and taken up out of the ground are located obliquely one nehind the other. After one-way ploughing between two opposed turn-lands, therefore,the borderlines betw¬ een the turn-lands and the ploughed field are saw-tooth shaped, i.e. unploughed triangular areas project from the turn-lands into the ploughed field. At the subsequ¬ ent ploughing of the turn-lands in a direction perpend¬ icular to the preceding one, these unploughed areas must be re-ploughed over a width corresponding to the length of the plough. This requires at least two addit¬ ional plough passes per turn-land, with corresponding labour and fuel costs involved.

Thw present invention has the object to propose a dev¬ ice, by which at ploughing with a plough of the kind referred to above in the introductory portion straight borderlines between the turn-lands and the ploughed area can be obtained.

This object is achieved due to the characterizing feat¬ ures defined in the attached claims.

An embodiment of the invention is described in greater detail in the following, with reference to the accomp¬ anying drawings, in which Fig. 1 is a perspective view of a conventional plough, and Fig. 2 is a correspond¬ ing view of a modified plough according to Fig. 1 with a schematically shown device according to the invention.

OMPI The plough shown in a simplified way in Fig. 1 compris¬ es in known manner a plough frame 10 placed obliquely in the ploughing direction. A plurality of plough units 11 are attached on the frame. Each plough unit 11 com¬ prises a plough body 12, a plough beam 13 supporting the plough body, and a plough beam holder l mounted on the plough frame 10.

In order to prevent the plough bodies 12 from being dam¬ aged when the plough strikes against obstacles, for example stones and the like, each plough beam 13 is hingedly attached to the associated holder 14 via a link 15 and a release mechanism 16, so that the plough bodies when striking against such obstacle pivot rear¬ ward-upward and pass over the obstacle on its upper surface. By means of these release mechanisms iβ attach¬ ed hingedly between each plough beam and holder, a resilient pressing force acting against the plough beam 13 is made available, which force at normal plough¬ ing resistance retains the plough bodies 12 in their positions lowered into the ground and, when an obstacle of the aforesaid kind has been passed, again presses the respective plough body 12 down to its position;.*, lowered into the ground.

At the embodiment shown, the release mechanisms..16 consist of single-acting hydraulic cylinders, which via conduits 17 communicate with a hydraulic accumulator 18, which is intended to receive at maintained pre- -load the liquid volume forced aside by the cylinders when the plough strikes against an obstacle. Said cyl¬ inders also communicate with a schematically shown pressure source 19, which normally consists of the hydraulic unit of the traction vehicle (not shown) .

At ploughing with known multi-share ploughs like the afore-described one, border areas 20 remain unplough¬ edv (according to dashed lines in Fig. 1) between the

OMPI ploughing pass 21 and the turn-land 22 of the traction vehicle, due to the fact that at the arrival of the plough at the turn-land 22 all plough bodies are lifted simultaneously. Corresponding unploughed areas are obt¬ ained also at the opposed ends of the ploughing pass 21 when all plough bodies are lowered into the ground sim¬ ultaneously (not shown). At subsequent ploughing of the turn-lands in a direction perpendicular to the plough pass 21, these areas 20 must be re-ploughed over a width corresponding to the total plough body distance of the plough, which implies at least two extra plough passes at every turn-land.

In Fig. 2 a modified plough according to Fig. 1 is shown, which is provided with a schematically shown hydraulic arrangement 30 according to the invention, by means of which uniform borderlines between plough furrows and turn-lands are obtained, so that all ridges of each plough pass 21 can be started (not shown) and completed on a borderline 24 to the turn-land 22 which is perpendicular to the ploughing direction.

The plough proper according to Fig. 2 differs from the plough shown in Fig. 1 substantially only, in that the conventional release mechanisms with maintained release function are replaced by double-acting hydraulic cylind¬ ers 26.

The hydraulic arrangement 30 coupled-in with the hydr¬ aulic cylinders 26 has the structural design as follows.

Between a suction conduit 42 and a pressure conduit 33 a hydraulic pump 31 , which may be located in the tract¬ ion vehicle, and a volume flow regulator 32 are coupled- -in. The pressure conduit 33 is branched off to a hydr¬ aulic accumulator 34 via a throttle valve 35 and a stop valve 36 coupled-in parallel with the throttle valve 3 ,

_. while in each of the pressure conduits 33 (2-4) for the remaining directional valves adjustable sequential valves 38 (2-4) with stop valves 39 connected in par¬ allel are coupled-in, which stop valves block in the pressure direction of the pump.

To the return connections at the inlet ends of the valves 37 (1-4) a return conduit 40 common to all ret¬ urn conduits is coupled-in to a tank 4l.

Each valve 37 is connected at the outlet ends to the two ends of the associated hydraulic cylinder 26 through conduits 27 and 28, respectively.

The plough and the hydraulic arrangement 30 are intend¬ ed to co-operate as follows.

At normal ploughing all directional valves 37 (1-4) are set in the position opposed to the position accord¬ ing to Fig. 2, i.e. all conduits 28 are coupled-in with associated pressure conduits 33_■ so that all cylinders 26 (1-4) are entirely extracted and retain the plough bodies in their swung-down positions. When one (or'-.more) of the plough bodies, for example the rearmost one, meets an obstacle, the piston rod is pressed into the associated cylinder 26 (4), whereby hydraulic liquid flows back through the conduit 28, valve 37 (4), stop valve 39, to the stop valve 36 and into the hydraulic accumulator 34, which at substantially unchanged press¬ ure receives the liquid volume forced aside. When the plough body has passed the obstacle, the hydraulic liquid is pressed back by the accumulator 34 through the throttle valve 35_. to the associated sequential ; 1 valve 38 (4), the conduit 28 and again into the hydraul¬ ic cylinder 26 (4), so that the plough body 12 again is pressed down into the relatively softer soil. Upon rel¬ ease caused by a stone, thus, a plough according to the invention operates in the same way as a conventional plough.

When the foremost plough body 12 (1) of the plough dur¬ ing the ploughing operation arrives at the borderline 24 at the turn-land 22, the ploughman adjusts the elec¬ tronically controlled directional valves 37 (1-4) to the position shown in Fig. 2. In this position all cond¬ uits 27 are coupled-in with the pressurer conduits 33- The foremost plough body 12..(1) hereby is lifted immedi¬ ately to the position according to Fig. 2 when the hydraulic liquid through the conduit 27 presses in the associated piston rod to the entirely retracted posit¬ ion. Due to the fact, that in the pressure conduit to the next following hydraulic cylinder 26.(2) a sequent¬ ial valve 38 (2) is located, which requires a higher pressure for opening the fluid passage to the second cylinder 26 (2), this piston rod is not retracted imm¬ ediately, but first after the time required before this higher pressure has been built up in the pressure cond¬ uit 33. This time can be adjusted to the desired value by adjusting the sequential valve 38 (2) to a corres¬ pondingly high opening pressure, i.e. to an opening pressure so high that the sequential valve 38 (2) opens after the time, which depending on the speed of the traction vehicle has passed from the moment when the first plough body 12 (1) has started the lifting-up movement until the second plough body 12 (2) arrives at the borderline 24 of the turn-land 22. In a corres-

Q--.PI ponding manner, the next following sequential valve 38 (3) is adjusted to an opening pressure higher than the preceding one, so that the directional valve 38 (3) ^' opens after the time having passed from the moment when the second plough body 12 (2) has started the liftings -up movement until the third plough body 12 (3) arrives at the borderline 24. The last sequential valve 38 (4) finally is adjusted to a still higher opening pressure, so that it opens first when the last plough body 12 (4) arrives at the borderline 24.

At the subsequent movement of the plough on the turn-^' -land, the plough frame 10 in known manner may require to be lifted for a greater ground clearance; in the case when it is supported by means of the draw-bars and top or pressure bar of the traction vehicle (not shown), in the case when it is partially supported or towed in addition and, respectively, only by elevating the frame axles of the supporting wheels (not shown) .

Prior to ploughing from a turn-land, the plough frame 10 again is lowered with all plough bodies in their swung-up positions. When the first plough body 12 (1) arrives at the borderline of the turn-land to the ^"-. =. ^• ploughing area, the ploughman adjusts all directional valves 37 (1-4) to the position opposed to- the position shown in Fig. 2. The plough bodies are lowered in a corresponding way and in the same order as described above for their li ting-up movement, so that all plough bodies 12 (1-4) also start the ploughing on a common line perpendicular to the ploughing direction.

When the plough has more plough bodies than the number shown, the hydraulic arrangement can be completed with additional cylinders 26, directional valves 37 and sequ¬ ential valves 38 with associated stop valves 39 and conduits. Alternatively the sequential valves 38 and stop valves 39 can be abolished entirely while all pressure cond¬ uits 33 are coupled-in directly with associated direct¬ ional valves 37. These valves in such a case can be ad¬ justed, for example, from an electronic sequential con¬ trol, which emits adjusting signals at time intervals, which can be adjusted to the normal speed of the tract¬ ion vehicle, but which also can be controlled by a speed or path transmitter coupled-in with a wheel of the traction vehicle, whereby variations in the speed of the plough (not shown) automatically can be compens¬ ated for.