Mowing machine

The invention relates to a mowing machine provided with a frame with a coupling member to be coupled to a tractor or the like, with a connecting piece which is pivotable with respect to said coupling member about an upwardly extending pivot pin located near one end of said coupling member, as well as with a frame beam carrying a plurality of mowing means, which is rotatable with respect to the coupling member about an upwardly extending pivot pin located near the end of the coupling member remote from the end of the coupling member adjoining the connecting piece, whilst means are provided that do not allow the frame beam to pivot about a pivot pin before the force exerted on the frame beam exceeds a predetermined value.

Such mowing machines are generally provided with a mechanical locking mechanism comprising a spring-loaded locking pin or the like, whereby said locking pin, when a force exerted on the frame beam exceeds a predetermined value, can move out against the spring force of the spring so as to enable a pivotal motion of the frame beam carrying the mowing means opposite the direction of movement during operation.

Such mechanical locking means are exposed to rusting and fouling, however, which will affect the intended operation of the locking means.

The object of the invention is to obtain a mowing machine of the above kind, wherein the drawbacks of the known constructions can be avoided and an effective moving out of the frame beam carrying the mowing means during operation can be ensured at all times when the forces exerted on said frame beam or on the connecting piece connecting the frame beam to the coupling member, as the case may be, exceed a certain value.

According to the invention this can be achieved in that a hydraulic setting cylinder is provided between the coupling member and the connecting piece as well as between the connecting piece and the frame beam, said setting cylinders being under pressure during normal operation and being incorporated in a hydraulic circuit, in such a manner that when a predetermined force on the frame beam and/or the connecting piece is exceeded, a pivotal motion occurs between the coupling member and the connecting piece and/or between the connecting piece and the frame beam.

Since hydraulic setting cylinders are used the construction will be highly insensitive to rusting and/or fouling, so that even after prolonged use of the mowing machine the frame beam carrying the mowing means will still move out at the intended force, whereby the connecting piece and/or the frame beam may slightly pivot backwards when the force exerted on the connecting piece and/or the frame beam exceeds a predetermined value, which is already sufficient in many cases in order to keep the forces exerted on the carrying part and/or the coupling member within allowable limits, whilst generally the frame beam will not pivot further backwards before a larger force is exerted on the frame beam.

A further advantage of the construction according to the invention is that, after the mowing machine has possibly been lifted from the ground, the coupling member and the frame beam can be pivoted back to the position suitable for operation by means of the hydraulic setting cylinders, without the tractor driver having to leave his position on the tractor, whilst the setting cylinders may also be used to shift the mowing machine from an operating position into a transport position, and conversely.

The invention will be explained in more detail hereafter with reference to an embodiment of the construction according to the invention illustrated in the accompanying Figures.

Figure 1 is a diagrammatic plan view of a mowing machine according to the invention, wherein the full lines illustrate the position suitable for operation and the dotted lines indicate a transport position and a position in which the mowing machine is partially pivoted backwards.

Figure 2 diagrammatically shows the arrangement of the hydraulic cylinders that form part of the mowing machine according to the invention.

As is diagrammatically shown in Figure 1 the mowing machine comprises a coupling member 1, which is to be coupled to an agricultural implement or the like, said coupling member in the illustrated embodiment being constructed so as to be attached to a three-point hitch of a tractor or the like.

One end of a connecting piece 2 is coupled to said coupling member 1 in such a manner, that said connecting piece is pivotable with respect to the coupling member 1 about a pivot pin 3 extending at least substantially vertically during normal operation.

A frame beam 5 is attached to the end of the connecting piece 2 remote from the pivot pin 3, by means of a pivot pin 4 extending parallel to the pivot pin 3. The frame beam 5 for example supports, in a manner known per se, a plurality of mowing means or mowing drums arranged in side-by-side relationship in a row, which are rotatable about upwardly extending axes of rotation and which are arranged under a protecting plate 6 secured to the frame beam 5, when seen in Figure 1. Said mowing means can be driven from the power take-off shaft of the tractor, via driving means located in a casing 7 extending parallel to the connecting piece or frame beam 2. The construction of such a mowing machine is quite common and need not be further explained or illustrated, therefore.

A hydraulic setting cylinder 8 is provided between the coupling member 1 and the connecting piece 2, spaced from the pivot pin 3 by some distance. Furthermore a hydraulic setting cylinder 9 is secured to the frame beam 5. As is illustrated in Figure 2 a piston rod 10 is accommodated in the setting cylinder 9, said piston rod at both ends being provided with sealing rings 10' co-operating with the inner wall of the cylinder 9. A central portion of the piston rod 10 forms a rack 11, whilst near said rack 11 a hole 12 is provided in the wall of the cylinder 9. The part of the rack 11 located near the hole 12 is in engagement with a gear (not shown), which is provided in a gear box 13 secured to the connecting piece 2. Said gear co-operating with the rack 11 is arranged in such a manner that the central axis of said gear coincides with the central axis of the pivot pin 4, whilst the gear has a fixed position with respect to the connecting piece 2.

Lines 14 and 15 respectively are connected to the ends of the setting cylinder 9.

Said line 14 is in communication with a line 17 via a non-return valve mechanism 16, which line 17 can be coupled to the hydraulic circuit of a vehicle, such as a tractor, propelling the mowing machine during operation.

As is furthermore shown in Figure 1, the setting cylinder 8 is provided with an attaching eye 18, by means of which the setting cylinder can be attached to the coupling member 1 or the connecting piece 2.

A piston rod 19 located inside the setting cylinder 8 is at one end provided with a piston 20 secured to said piston rod 19. The end of the piston rod 19 remote from the piston 20 is passed through a stuffing box 21, whilst at its end projecting from the setting cylinder 8 said piston rod is provided with an attaching eye 22, for attachment to the connecting piece 2 or the coupling member 1.

The setting cylinder 8 is illustrated in the position which it will at least substantially occupy during normal operation of the mowing machine, i.e. with the piston rod 19 and the piston 20 attached thereto moved into the setting cylinder 8 as far as possible.

The end of the setting cylinder 8 located near the stuffing box 21 is connected to the line 14 via a line 23. The line 15 is connected to the interior of the setting cylinder 8, via a line 24, in a point located at the side of the piston 20 remote from the piston rod 19. Furthermore the free end of the line 15 may also be connected to the hydraulic circuit of a tractor or the like vehicle propelling the mowing machine during operation.

At one end located near the stuffing box 21 the interior of the setting cylinder 8 is furthermore in communication with a connector 25, via which the interior of the setting cylinder 8 is in communication with an accumulator 26, in which a pressure of e.g. 100 - 120 bar prevails during normal operation. Furthermore an adjustable pressure relief valve 27 is connected to the connector 25, which pressure relief valve shuts off the connection between the connector 25 and one end of a line 28 during normal operation. The end of the line 28 remote from the connecting piece 25 is in turn in communication with the interior of the setting cylinder 8, at a point located at the side of the piston 20 remote from the piston rod 19, near the same end of the setting cylinder 8 as to which the line 24 is connected.

The pressure relief valve 27 opens at a pressure of e.g. ± 180 bar. Another valve mechanism 29 is provided between the lines 17 and 15, via which fluid can be passed from the line 17 to the line 15 and which allows fluid to flow back into the line 15 when the pressure in the line 17 exceeds a pressure of e.g. 120 bar.

Furthermore a line 30 is provided between the valve mechanism 16 and the line 15, whose purpose will be described in more detail hereafter.

During normal operation, when both the connecting piece 2 and the frame beam 5 carrying the mowing means extend transversely to the intended direction of movement according to the arrow A, the piston rods 10 and 19 are located inside the setting cylinders 8 and 9 respectively, in the position shown in Figure 2. In the interior of the setting cylinder 8 as well as in the interior of the left-hand part, when seen in Figure 2, of the setting cylinder 9, via the lines 23 and 14, a pressure corresponding with the pressure in the accumulator 26 will prevail, i.e. a pressure of e.g. 100 - 120 bar.

When, for example, the forces exerted on the frame beam and/or the connecting piece 2 via the mowing means exceed a predetermined value, the pressure in the setting cylinder 8 may become higher than the pressure prevailing in the accumulator 26, as a result of which the setting cylinder 8 will move out, whilst squeezing fluid from the setting cylinder to the accumulator. It will be apparent that consequently the connecting piece 2 and the frame beam 5 carried by the connecting piece can pivot backwards about the shaft 3, opposite the direction of movement. When the forces exerted on the frame beam 5 or the frame beam 2, as the case may be, decrease again the setting cylinder 8 can return to its original position again, because the pressurized fluid flows back from the accumulator 26 into the setting cylinder 8.

When the force exerted on the frame beam 5 and/or the frame beam 2 further increases, however, it is possible that at a given moment the pressure in the interior of the setting cylinders 8 and 9 exceeds the pressure at which the pressure relief valve 27 opens. In that case the fluid can escape from the left-hand part of the setting cylinder 9 via the lines 14 and 23, the interior of the setting cylinder 8, the open valve 27, the line 28, the line 24 and the line 15, in order to flow back into the right-hand part, when seen in Figure 2, of the setting cylinder 9 via the line 15.

In that case the piston rod 10 and the rack 11 integral therewith will move towards the left, when seen in Figure 2. It will be apparent, that the rack 11 will also move with respect to the gear fixed to the connecting piece 2 and being accommodated in the gear box 13 thereby, all this in such a manner that the frame beam 5 will pivot backwards about the pivot pin 14 with respect to the connecting piece 2, in clockwise direction, when seen in Figure 1.

After the obstacle that caused the allowable force exerted on the frame beam 5 and/or the connecting piece 2 to be exceeded has been removed and/or the mowing machine has been lifted by means of the three-point hitch of the vehicle propelling the mowing machine, the machine may be returned to the position suitable for operation. For this purpose pressurized oil may be supplied, by operating a suitable valve provided on the vehicle in question, to the line 17 of the hydraulic circuit on the mowing machine illustrated in Figure 2. Said pressurized oil will be supplied, via the valve 16 and the lines 14 and 23, to the left-hand ends, when seen in Figure 2, of the setting cylinders 9 and 8, as a result of which the piston rods 10 and 19 will be moved towards the right again, when seen in Figure 2, to the positions illustrated in Figure 2. The fluid present in the right-hand portions of the cylinders 8 and 9 in question can flow back to the hydraulic circuit of the tractor via the line 15.

The valve 27 will close automatically and the pressure in the accumulator 26 will return to the desired value of 100 - 120 bar, which is ensured by the setting of the valve 29, which will discharge fluid supplied via the line 17 to the line 15 when the desired pressure in the accumulator 26 is reached.

The above-described setting cylinders 8 and 9 may also be used in order to put the mowing machine in its transport position, in which, as indicated in Figure 1, the frame beam 5 carrying the mowing means is pivoted clockwise through ± 180° with respect to the connecting piece 2, from the normal operating position illustrated in full lines to the transport position illustrated in dotted lines, in which the frame beam 5 carring the mowing means is located at least substantially entirely behind the tractor or the like, when seen in the intended direction of movement.

In order to put the mowing machine in its transport position pressurized oil is supplied to the line 15 by suitably controlling a valve, which forms part of the hydraulic circuit of the tractor or the like. Said pressurized oil is therefore supplied to the right-hand ends, when seen in Figure 2, of the setting cylinders 8 and 9, as a result of which the piston rods 19 and 10 will be moved towards the left, when seen in Figure 2. Consequently the connecting piece 2 will be pivoted clockwise, when seen in Figure 1, about the pivot pin 3, whilst furthermore the frame beam 5 will be pivoted through ± 180° with respect to the connecting piece 2, when seen in Figure 1, about the pivot pin 4. The oil which is squeezed out of the left-hand ends of the setting cylinders 9 and 8, when seen in Figure 2, can flow back to the hydraulic circuit of the tractor via the valve mechanism 16, which is opened by the pressure in the line 30, through the lines 14, 23 and 17.

When the pressure in the line 15 exceeds a predetermined value, oil can escape from the line 15 to the line 17 via the valve mechanism 29, and flow back from said line 17 to the hydraulic circuit of the tractor.

In order to return the mowing machine from the transport position to the position suitable for operation pressurized oil may again be supplied to the line 17, as described above, as a result of which the piston rods 10 and 19 will return to the position shown in Figure 2.