GB2058531A - Reversible plough - Google Patents

Abstract

When the plough frame of a semi-mounted rotary plough is rotated from one working position into the other, it is rotated over the mounting wheel. During this process, high moments of rotation act on the tractor so that its stability may be endangered. In order to reduce these moments of rotation, a proportion of the plough frame weight is systematically transferred to the tractor during the rotational process without notably lifting the plough frame. For this purpose, there serves the upper link rod of the three-point linkage, which link rod is designed as a hydraulic cylinder 15. <IMAGE>

Description

SPECIFICATION Reversible plough The invention relates to a method for rotating the plough frame of a semi-mounted rotary plough whose centre of gravity is laterally disposed beside the axis of rotation or turn and wherein the plough frame, which is hinged to the rotary part of the plough head, is moved, preferably into two rota tional phases, by means of rotary cylinders which engage in the rotary part of the plough head, over the mounting wheel. The invention furthermore relates to a semi-mounted rotary plough for the per formance of the method.

Because of their large working width, semi mounted rotary ploughs are of great importance for cultivating the soil and thus for the further mechan isation of agriculture. On account of the fact that the tractor and the plough form workwise one unit, the rotation of the plough frame is particularly important, due to the heavy weight thereof. During this process, the plough frame has to be moved over the mounting wheel by a robust rotating device, causing high moments of rotation to be transferred to the tractor, which may considerably affect the stability thereof. Such moments of rotation arise because the centre of gravity of the plough frame lies outside the axis of rotation.

In known methods, the plough frame is moved into the semi-rotated position when the headland is reached, is held in this position during the reversal on the headland and is then swung into the new plough position as it is introduced into the furrow.

The position of the centre of gravity of the plough frame remains substantially unaltered and outside the axis of rotation during the turning operation, the axis of rotation intersecting the point of fixing of the stabiliser on the plough head and the point of support of the mounting wheel. Due to the position of the point of gravity in relation to the axis or rotation or turn, there arise the mentioned high moments of rotation when the plough frame is rotated according to this method.

There are known semi-mounted rotary ploughs (GB PS 1 319957 and DE GM 78 34 402) wherein the plough frame is rotated according to the mentioned method with the aid of suitable rigidly designed rotary cylinders as the rotating devices. In orderto ensure a sufficient stability, the track of the tractor has to be of a corresponding width or the force exerted by the rotary device has to be of a corresponding dimension, since the plough frame weight as such cannot be reduced on account of the required stabilisation values and the centre of gravity of the system thus cannot be changed. It has turned out that wide-track tractors and special driving techniques are necessary for the provision of stability. However, vehicles of this kind are subject to special traffic and safety regulations so that their use is restricted.The task underlying the invention is to provide a method for rotating the plough frame and to design a semimounted rotary plough in such a way that the plough frame can be rotated without any special driving techniques and without endangering the stability of a tractor that has a normal track width.

According to the invention, the problem is soived in that during the preparation andlor during the rotation of the plough frame from one plough position into the other, additional weight is transferred from the plough to the tractor. By relieving the load of the plough, and thus that of the mounting wheel, the moments of rotation can be avoided altogether or at least to a considerable extent. As a result, the stability of the tractor and the semi-mounted rotary plough is decisively improved so that normal track width tractors can be used. At the same time, the work that has to be performed during the rotation is reduced by the lifting of the plough shares from the soil.

According to the invention, the desired stability of the tractor is provided, in particular, if the load of the plough is reduced only to such an extent that the arising moments of rotation are approximately zero.

The plough itself is only to be relieved of its load and is not to be lifted as a whole, the weight taken over by the plough having to be transferred through the plough head to the tractor.

For the performance of the method, there serves a semi-mounted rotary plough which comprises a plough frame, which is hinged to the plough head, and preferably a three-point linkage for connection to the tractor, the upper link rod of the three-point linkage being designed, according to the invention, as a hydraulic working cylinder.

On a semi-mounted rotary plough of such a design, the mounting wheel is relieved from pressure through the working cylinder, that is to say through the upper link rod, so that, if the relief is adequate, the moments arising during the rotation come to equal zero. Since additional weight of the plough is transferred to the tractor during this process, the stability thereof is additionally increased. In addition, that proportion of the weight that is transferred from the semi-mounted rotary plough to the tractor through the upper link rod does not have to be rotated by the rotating mechanism itself, so that the rotating operation is also facilitated. Furthermore, due to its relief, the mounting wheel can be moved more easily to the opposite position.

According to an advantageous development of the invention, provision is made for the upper link rod to be a working cylinder provided with a piston disc. By this means, it is possible to transfer a proportion of the plough frame weight to the rear-wheel axle of the tractor by means of pulling forces in the second phase of rotation and to use the tractor itself for cushioning the rotational movement. Such a working cylinder is used on both sides and is so connected in the second rotational phase that the working cylinder has to be lengthened through the weight of the plough.

The advantage of relieving the mounting wheel while the rear wheels of the tractor are simultane The drawing(s) originally filed was/were informal and the print here reproduced is taken from a later filed formal copy.

ously loaded has a particularly advantageous effect in the device according to the invention if the upper link rod is so connected that it is loaded with pressure fluid at the ring end priorto or simultaneously with the rotary cylinder.

The lifting-out and the rotation of the plough frame are particularly simplified, even under difficult conditions, if the upper link rod is connected so as to communicate with the rotary cylinder. Such a connection serves for a uniform sequence of movements because shocks caused by the fact that loading of the cylinders occurs irregularly or at time intervals are prevented.

For further optimising the connection, provision is made, according to a development of the invention, for the upper link rod and the rotary cylinder to be connected so as to communicate at the piston end and for a pressure limiting valve to be arranged in the connection line to the connection at the cylinder end. By this means, the upper link rod can be used in the second rotational phase as a cushioning element which prevents the plough frame from being low ered too quickly or too jerkily.

It is advantageous to combine the pressure limiting valve with a restrictor. The restrictor may be arranged in the piston disc. The medium flowing to the upper link rod through the pressure limiting valve at the cylinder end is so influenced through the restrictor that the cushioning effect is equalised and stabilised over the entire movement cycle.

Damage to the upper link rod, which is arranged between the tractor and the plough, or to the tractor and the plough during the individual rotating and working processes is prevented, according to the invention, in that the upper link rod is pivotally mounted between the plough head and the lower fixing point of the three-point linkage. The upper link rod is capable of readily absorbing the individual movements, even during the long working paths between the individual rotational phases on the headland, and of equalising them between the tractor and the plough.

The plough head freedom of movement in the transporting position and also in the working position is ensured, any damage being simultaneously prevented, if, according to one design of the invention, the upper link rod comprises a free wheel which is operative in the semi-rotated position of the plough frame or if the piston rod and the swivel pin are interconnected by a multiple-link chain.

The invention is particularly characterised in that the moments of rotation acting on the tractor as a result of the turning of the plough frame are reduced or eliminated in an advantageous manner, the pulling force exerted by the upper link rod simultaneously loading the rear axle ofthetractorwith a proportion of the plough weight during the rotation. By this means, the negative position of the centre of gravity beside the axis of rotation or turn, which is the result of the construction of the semi-mounted rotary plough, is eliminated in a simple manner. Due to the thus obtained stability of the tractor, it is possible to use normal track width tractors for heavy semi-mounted rotary ploughs.

Further details and advantages of the subject matter of the invention will emerge from the following description of the accompanying drawings, in which, a preferred exemplified embodiment is shown with the details and components necessarytherefor. In the drawings: FIGURE 1 shows a semi-mounted rotary plough according to the invention in a side view, FIGURE 2 shows the semi-mounted rotary plough in a top view and FIGURE 3 shows a connection diagram showing the upper link rod and the rotary cylinder.

The semi-mounted rotary plough shown in Fig. 1 is a construction wherein the semi-mounted rotary plough, which is generally designated 1, consists of the plough frame 2, which carries the plough shares 3, 4, as well as the mounting wheel 5 and the plough head 7. The stabiliser 6, over which the plough frame 2 is lifted with the aid of the rotary cylinder 10, serves for supporting the mounting wheel 5 and for connection to the plough head 7. The rotary cylinder 10 engages in the rotary part 8, on the one hand, and in the plough head 7, on the other hand.

A three-point linkage, which is generally designated 12, serves for connecting the plough head 7 and thus the semi-mounted rotary plough 1 to the tractor not shown. The three-point linkage 12 consists of the two lower link rods 13, 14 and the upper link rod 15.

According to the invention, this upper link rod 15 is designed as a hydraulic working cylinder which is secured, by its upper fixing point 16, to the plough head 7, on the one hand, and, by its lower fixing point 17, to the fixing point of the three-point linkage, on the other hand, a chain 46 being provided therebetween. The lower fixing point 17 lies in the zone of the rear axle of the tractor not shown. By this means, it is possible theoretically to lift the plough frame 2 through the upper link rod 15 which is designed as a hydraulic working cylinder. The inward movement of the piston 36 causes a proportion of the weight of the plough frame 2 to be transferred to the tractor, more especially to the rear axle thereof.This load is evenly distributed to both wheels so that the moments of rotation arising during the rotation of the plough frame 2 cannot impair the stability of the tractor or can do so only to a very slight extent.

The arrangement of the upper link rod 15 is illustrated in Figures 1 and 2, Fig. 1 showing in particular that the upper fixing point 16 of the upper link rod 15 and the rotary cylinder 10 are preferably at the same distance from the rotary part 8. In addition to the chain 46, which engages in the lower fixing point 17, the upper link rod 15 may be provided with a free wheel 45, which effectively prevents too far an inward movement of the upper link rod. The axis of rotation about which the plough frame 2 has to be rotated is generally designated 43.

In Fig. 3, there is illustrated, in particular, the cooperation between the rotary cylinder 10 and the upper link rod 15 with the aid of connection symbols.

Both are designed as hydraulic working cylinders provided with disc pistons 19, 20. Their cylinders 29, 35 have fixing facilities, there being provided, in the example shown, swivel eyes 30, 33 at the cylinder ends and spherical joints on swivel pins 31,34 at the piston ends. The rotary cylinder 10 is connected to the rotary part 8 through a crank arm 38, while the upper link rod is hinged directly to the lower fixing point 17.

The cylinder chamber of the rotary cylinder 10 is connected to the corresponding chambers of the upper link rod 15 through the connection 21 at the piston end and through the connection 22 at the cylinder end. In the connections 21, 22, there are arranged non-return valves 23, 24 in such a way that, at the cylinder end, the pressure medium can only flow from the upper link rod to the rotary cylinder and, at the piston end, it can only flow from the rotary cylinder 10 to the upper link rod 15. The two connections 21, 22 are, in turn, connected through the connection line 25, this connection being regulated through a pressure limiting valve 26 provided with a restrictor 27. The pressure limiting valve 26 ensures that the upper link rod 15 functions as a dashpot when the semi-mounted rotary plough or the plough frame thereof is swung downwards.

In Fig. 3, there is shown a situation in which the plough frame 2 has been swung downwards. When the tractor with the attached semi-mounted rotary plough reaches the end of the field to be ploughed, pressure medium is fed through the line 40 to both the rotary cylinder 10 and the upper link rod 15. The pressure medium is evenly applied to both, since the cylinder chambers are connected through the connection line 21 and the flow is not restricted by the non-return valve 23. There does not occur any excessive pressure build-up, since the pressure is determined by the pressure limiting valve 26.

When the upper dead centre position is reached, the flow of the pressure medium through the line 40 is stopped. When the dead centre position has been overcome by suitable measures, which will not be explained here, pressure medium is applied to the rotary cylinder 10 at the cylinder end through the supply line 41. On account of the non-return valve 24 having been connected into the connection 22, there initially does not occur any application to the upper link rod 15 at the cylinder end. Only when the pressure of the pressure medium, which is supplied from the rotary cylinder 10 at the piston end, exceeds the specified value on the pressure limiting valve 26, is the disc piston 20 of the upper link rod 15 slowly relieved so that it can be extended. In this way, the upper link 15 acts in a cushioning manner as the plough frame is swung downwards without the need of any special devices to this end.

When the end position of the rotary cylinder 10 has been reached, the rotation process is completed.

The plough frame 2 has been rotated into the furrow, and the plough can resume its work proper.

Claims (14)

1. A method for rotating the plough frame of a semi-mounted rotary plough whose centre of rotation is laterally disposed beside the axis of rotation or turn, the plough frame, which is hinged to the rotary part of the plough head, being moved, preferably in two rotational phases, by means of rotary cylinders, which engage in the rotary part of the plough head, over the mounting wheel, characterised in that additional weight is transferred from the plough to the tractor during the preparation and/or during the rotation of the plough frame from one plough position to the other.

2. A method as claimed in Claim 1, characterised in that the plough is relieved from its load only to such an extent that the arising moments of rotation are approximately zero.

3. A semi-mounted rotary plough comprising a plough frame, which is hinged to the plough head, and preferably a three-point linkage for connection to the tractor for the performance of the method as claimed in Claims 1 and 2, characterised in that the upper link rod of the three-point linkage is designed as a hydraulic working cylinder.

4. A semi-mounted rotary plough as claimed in Claim 3, characterised in that the upper link rod is a working cylinder with a piston disc.

5. A semi-mounted rotary plough as claimed in Claim 3, characterised in that the upper link rod is so connected that it is loaded with pressure fluid at the ring end before or simultaneously with the rotary cylinder.

6. A semi-mounted rotary plough as claimed in Claim 3, characterised in that the upper link rod is connected so as to communicate with the rotary cylinder.

7. A semi-mounted rotary plough as claimed in Claim 3 and Claim 6, characterised in that the upper link rod and the rotary cylinder are so connected that they communicate at the piston end and in that a pressure limiting valve is arranged in the connection line to the connection at the cylinder end.

8. A semi-mounted rotary plough as claimed in Claim 7, characterised in that the pressure limiting valve is combined with a restrictor.

9. A semi-mounted rotary plough as claimed in Claim 8, characterised in that the restrictor is arranged in the piston disc.

10. A semi-mounted rotary plough as claimed in Claim 3, characterised in that the upper link rod is pivotally mounted between the plough head and the lower fixing point of the three-point linkage.

11. A semi-mounted rotary plough as claimed in Claim 3 and Claim 10, characterised in that the upper link rod has a free wheel in the semi-rotated position ofthe plough frame.

12. A semi-mounted rotary plough as claimed in Claim 3 and Claim 10, characterised in that the piston rod and the swivel pin are interconnected through a multiple-link chain.

13. A method for rotating the plough frame of a semi-mounted rotary plough substantially as described herein.

14. A semi-mounted rotary plough substantially as described herein with reference to the accompanying drawings.