FRONT LIFTING DEVICE FOR A TRACTOR AND METHOD FOR OPERATING A TRACTOR'S FRONT LIFTING DEVICE

The present invention relates to a front lifting device, which front lifting device includes a frame component, a pushing arm, lifting arms, and cylinders for operating the lifting arms.

A front lifting device according to the prior art is shown in Figure 1. A conventional front .lifting device includes a frame component, a pushing arm, lifting arms, and cylinders for operating the lifting arms. The pushing arm, lifting arms and cylinders form the implements attachment means . The front lifting device is connected to the tractor from its frame. When implements are attached to the front lifting device, the trac- tor should be driven at precisely the correct angle relative to the implement, so that the implement can be attached to the tractor .

In addition, implements attached to the conventional attachment means of a tractor are known from the prior art, which include means for rotating the implement to the side. Such an application is disclosed in, among others, publication NL 8500976. In such a solution, each implement must include means for rotating the implement to the side. As each implement includes means for rotating the implement to the side, the use of many separate implements is accompanied by considerable manufacturing costs. In addition, the means in an implement for rotating the implement to the side are of no benefit When attaching the implement to the tractor. In addition, the means in the implement for rotating the implement to the side make the totality unnecessarily long.

The invention is intended to create a front lifting device that is more versatile in use. The characteristic features of the present invention are, that the front lifting device includes, in addition, a rotating frame, which is attached to a frame component by means of a vertical shaft, and means for attaching

an implement are attached to the rotating frame. The invention is also intended to create a method, which permits an implement to be attached more easily than before. The characteristic features of the present invention are, that the implement attaching means are arranged to be rotated horizontally relative to the chassis of the tractor.

A front lifting device is used when attaching many kinds of implement to a tractor. Such implements are used, for example, in real-estate maintenance, and, for example, in haymaking in agriculture. The tractor includes a chassis, to which the front lifting device is attached. Further, the front lifting device includes implement attachment means. In addition, the implement attachment means are rotated horizontally relative to the chassis of the tractor. The term horizontal refers to the horizontal direction, i.e. transverse direction, relative to the tractor's chassis. The term vertical refers, in turn, to the vertical direction of the tra,ctor's chassis. If the tractor tilts, the set of examination co-ordinates tilts relative to the tractor's chassis. The implement rotates horizontally relative to the tractor. When the implement rotates relative to the tractor, the implement follows a different path to that of an implement that is in the middle of the tractor. The implement, which follows a different path to the tractor, can be, for example, a brushing machine. Such a brushing machine can be run next to the kerb at intersections, even though the nose of the tractor avoids the kerb. In other words, the brushing machine can be controlled separately from the tractor.

In one embodiment, the attachment means are arranged to turn according to a selected function when the tractor turns. Thus the operator need not both steer the tractor and control the implement. It is enough for the operator only to steer the tractor and select the function. Thus, when the tractor turns, the implement attachment means in the front lifting device, and, further, the implement turns automatically in a manner controlled by the selected function. The turning of the tractor

can be based on the turning of the front wheels, the rear wheels, or the chassis. Turning can be either measured, or determined directly from a steering command.

In a second embodiment, the implement attachment means include two lifting arms. In addition, the lifting arms move vertically independently of each other. As the lifting arms move independently of each other, the attachment of implements to the front lifting device is easier than previously. In addition, the operation of implements is more versatile, as they can be tilted by moving the attachment means vertically.

In the following, the invention is examined in detail with reference to the accompanying drawings showing some embodiments of the invention, in which

Figure 1 shows a front lifting device according to the prior art, Figure 2 shows schematically a bottom view of the tractor with the front lifting device according to the invention, with the rotating frame turned,

Figure 3 shows the front lifting device according to the invention, with the rotating frame turned, Figure 4 shows the front lifting device according to the invention, with the rotating frame straight and the lifting arms at different levels,

Figure 5 shows the front lifting device according to the invention, with the rotating frame turned and the lifting arms at different levels, Figure 6 shows a tractor with a front lifting device, which includes an active control system,

Figure 7a shows a tracking selector, for selecting a function, Figure 7b shows an example of the position between the front wheels of the tractor and the front lifting device, when the tracking selector is in the state shown in

Figure 7a,

Figure 8a shows the tracking selector, when the function selected is to follow the steering at the same angle,

Figure 8b shows an example of the position between the front wheels of the tractor and the front lifting device, when the tracking selector is in the state shown in

Figure 8a, Figure 9a shows the tracking selector, when the function selected is the follow the steering at a smaller angle,

Figure 9b shows an example of the position between the front wheels of the tractor and the front lifting device, when the tracking selector is in the position shown in Figure 9a, Figure 10a shows the tracking elector, when the function is not to follow the steering, Figure 10b shows an example of the position between the front wheels of the tractor and the front lifting device, when the tracking selector is in the position shown in Figure 10a, and

Figure 11 shows the front lifting device according to the invention in operation.

Figure 1 shows a front lifting device 10' according to the prior art, which is arranged to be attached to the chassis of a tractor by a frame component 12'. Further, the frame component 12' includes a pushing arm 14', lifting arms 16', and cylinders 18'. The pushing arm 14' and the lifting arms 16' form together the implement attachment means 26'. The front lifting device 10' also includes a power-take-off 20', so that the implement will receive the power it needs . As during operation the attachment means 26' remain in the same constant direction relative to the frame component 12' and further the chassis of the tractor, their operation is very restricted.

Figure 2 shows schematically a bottom view of the tractor 28, with the rotating frame 24 of the front lifting device 10

according to the invention being turned. Only the chassis 32, the front axle 34, the rear axle 36, the front wheels 38, the rear wheels 40, and the front lifting device 10 of the tractor are shown. The front lifting device 10 includes a frame com- ponent 12, from which the front lifting device 10 is arranged to be attached rotatably to the chassis 32 of the tractor. The front lifting device 10 also includes implement 30 attachment means 26, for attaching an implement 30 to the front lifting device 10. The front lifting device 10 includes, in addition, a rotating frame 24, which is attached to the frame component 12 by a vertical shaft 22. The attachment means 26 are attached to the rotating frame 24. In other words, the attachment means 26 for attaching the implement 30 rotate together with the rotating frame 24. The attachment means 26 include two lifting arms 16. A ploughing plate 42 is the implement 30 attached to the lifting arms 16.

The tractor shown in Figure 2 includes a front axle 34, for supporting the front wheels 38 on the tractor's chassis 32. The distance d between the vertical shaft 22 and the front axle 34 is less than 800 mm, preferably less than 500 mm. As the vertical shaft 22 is close to the front axle 34, the rotation of the implement 30 attachment means 26 takes place close to the chassis 32 of the tractor. This makes the operating combination formed by the tractor and the rotatably operated implement as short as possible. The short operating combination permits work in even smaller spaces than previously. In addition, the implement then goes close to the wheel, in a direction that is as close as possible to that of the wheel, thus simplifying the overall control of the implement attachment means based on the turning of the tractor.

Figure 3 shows the front lifting device 10 according to the invention, which is arranged to be attached to the tractor from the frame component 12. A rotating frame 24 is attached to the frame component 12 through a vertical shaft 22. The rotating frame 24 is rotated relative to the frame component 12 and at

the same time relative to the tractor. The lifting arms 16 rotate together with the rotating frame 24, so that the lifting arms 16 also rotate relative to the frame component 12.

The rotating frame 24 shown in Figure 3 includes an attachment point 15 for the pushing arm. The front lifting device includes the necessary number of pushing arms, so that the attachment points can be more than one. Typically there is one pushing arm. The front lifting device includes at least one lifting arm. Typically the front lifting device includes two lifting arms. However, a front lifting device, in which there is only one lifting arm, can be implemented. The lifting arms are operated by cylinders .

In the front lifting device shown in Figure 3, the rotating frame 24 is supported on the frame component 12 by means of a vertical shaft 22. The pushing arm attachment point 15, the lifting arms 16, and the cylinders 18 are attached to the rotating frame 24. Thus the implement attachment means 26 are the pushing arm 14, the lifting arms 16, and the cylinders 18 for operating the lifting arms 16. The rotating frame in question permits the lifting arms to be rotated relative to the chassis of the tractor. In practice, this facilitates, for example, coupling an implement to the tractor. When using a front lifting device according to the prior art, the tractor must be driven at exactly the right angle relative to the implement, which makes it difficult to couple the implement. The rotating frame makes it possible to rotate the lifting arms, allowing them to be rotated as required when coupling an implement to the tractor. The front lifting device according to the invention is of benefit also in many work tasks. Such a work task is, for example, mowing.

The front lifting device according to the invention, shown in Figure 3, includes a rotating operating device 44 for rotating the rotating frame 24 relative to the frame component 12. The rotating operating device 44 is inside the rotating frame 24

and the frame component 12, but can be seen thanks to the cut-away view. The rotating device 44 is preferably a hydraulic rotating cylinder 46. The rotating cylinder is a hydraulic cylinder, as by using a hydraulic cylinder sufficient force and precision can be obtained. In addition, the operation of a hydraulic operating device is advantageous, as it is easy to attach to the tractor.

Figure 4 shows the front lifting device 10 according to the invention, to the frame component 12 of which the rotating frame 24 is attached by means of a vertical shaft 22. The rotating frame 24 is straight relative to the frame component 12 and also relative to the tractor. The implement attachment means 26 includes two lifting arms 16. In addition, the lifting arms 16 include their own lift operating devices 48, for operating the lifting arms 16. The lift operating devices 48 are hydraulic cylinders 18. The lifting arms 16 attached to the rotating frame 24 can be at different heights, as in the figure, as they are arranged to move vertically independently of each other. The lifting arms 16 are attached to the rotating frame 24 by means of pivots 52, which permit the lifting arms 16 to move vertically relative to the rotating frame 24. Because the pivots can be made to be sturdy, the lifting arms need not support each other. As the lifting arms are not supported by each other, they are free to move vertically independently of each other. This permits implements to be operated more freely than previously.

Figure 5 shows a front lifting device 10 according to the invention, in which the rotating frame 24 has ben turned relative to the frame component 12 and the lifting arms 16 are at different levels. In addition, the lift operating devices 48 are hydraulic cylinders 18. The fact that both lifting arms have their own hydraulic lifting cylinders is surprising in the light of traditional dimensioning, as traditionally the lifting cylinders have been dimensioned to lift the nominal load together. In that case, however, the lifting cylinders must operate

together, with a mechanical element transmitting the force between them.

In the front lifting device 10 shown in Figure 5, the implement 5 attachment means 26 include two lifting arms, which include their own lift operating devices 48 for operating the lifting arms 16. In addition, the lift operating devices 48 are hydraulic cylinders 18, which move the lifting arms 16 vertically independently of each other. There is no mechanical connection

10 between the lifting arms 16, which would transmit the force created by the lifting cylinders between the lifting arms, to lift the load. For this reason the lift operating devices, more specifically the hydraulic lifting cylinders, are dimensioned according to the nominal load. Though lifting power is lost,

15 the benefits achieved compensate for the lost lifting power, as nowadays there is no difficulty in creating lifting power. As a totality, the lifting arms are arranged to move in the vertical direction independently of each other, thus achieving a greater degree of freedom in controlling the implement. The

20 power required by the implement is taken from the power-take-- off 20.

Figure 6 shows a tractor 28, in which there is a front lifting device 10 according to the invention. The front lifting device

25 10 includes an active control system 54 for turning the rotating frame 24 according to a selected function, when the tractor 28 turns. In other words, when the tractor 28 turns, the rotating frame 24 is turned on the basis of tractor steering measurement data 56 obtained from the tractor's 28 control

30 system 60. The tractor steering measurement data 56 is transmitted to the rotating frame's 24 control system 54 using measurement-data 56 transmission means 58. The tractor's steering, i.e. turning data can be indirectly taken from the data going to the tractor's control system. On the other hand, the

35 turning of the tractor can be measured directly. The active control system 54 of the rotating frame 24 preferably includes a steering-angle sensor 62, for determining the turning of the

tractor 28 and controlling the rotating frame 24 on its basis. In other words, the active control system 54 commands the rotating frame 24 to turn according to a selected function relative to the tractor 28. The active control system 54 of the rotating frame 24 includes turning-data 64 transmission means 66, for controlling the operating device 48 of the rotating frame 24.

The active control system 54 of the rotating frame 24, shown in Figure 6, includes a turning-angle sensor 68, for measuring the turning of the rotating frame 24. Turning measurement data 70, which are sent to the processing unit 74 by turning measurement data transmission means 72, are obtained from the turning-angle sensor 68.

The active control system 54 of the rotating frame 24, shown in Figure 6, includes function selector means, i.e. a tracking selector 76, by means of which the ratio between the steering-- angle sensor and the turning-angle sensor is arranged to be defined. The tracking selector 76 includes a first regulating element 78 and a second regulating element 80. Function selection data 84 go from the tracking selector 76 to the processing unit 74, in order to create the rotation data 64.

The active control system of the front lifting device according to the invention, shown in Figure 7a, includes a tracking selector 76, for selecting the desired function. In other words, the tracking selector 76 acts as a user interface, by means of which function selection data 84 is given to the processing unit 74 (Figure 6) . A second selector element 80, which is preferably a stepped regulating element 88, is used to select the basic mode. A stepped regulating element is used in selecting the basic mode, as an alternative from one of the basic modes is selected for use. In the front lifting device according to the example, there are four basic modes. For its part, the first regulating element 78, which is preferably a stepless regulating element 86, is used to adjust the basic

mode more precisely. The basic mode is adjusted more precisely using the stepless regulating element 86, as the stepless regulating element permits the desired response between the turning of the tractor and that of the rotating frame.

In Figure 7a, the stepped regulating element 88 has been used to select basic state 1 for use. In basic state 1, the turning of the rotating frame is not affected by the steering of the tractor. In other words, the operator can turn the rotating frame as desired, independently of the turning of the tractor. When the stepless regulating element is rotated to the extreme clockwise position, the rotating frame is in the extreme position to the right, irrespective of the tractor's steering. In turn, when the stepless regulating element 86 is rotated to the extreme counterclockwise position, the rotating frame 24 is in the extreme position to the left, irrespective of the tractor's steering (Figure 7b) .

Figure 7b shows an example of the alignment between the front wheels 38 of the tractor 28 and the rotating frame 24 of the front lifting device 10, when the tracking selector is in the state shown in Figure 7a. In the basic state 1, the front wheels 38 and the rotating frame 24 can be turned in opposite directions, as the position of the rotating frame does not depend on the position of the front wheels. In the basic state

1, the position of the rotating frame is adjusted using the first regulating element 78 (Figure 7a) .

Figure 8a shows the tracking selector 76, in which the stepped regulating element 88 has been used to select the basic state 2 for use. The stepped regulating element 88 is preferably a selector switch 92. When the selector switch 92 is used to select the basic state 2, the rotating frame follows the steering of the tractor. In other words, when the wheels turn, the rotating frame also turns. In that case, the stepless regulating element 86 is used to adjust the ratio between the tractor's steering and the turning of the rotating frame. The

stepless regulating element 86 is preferably a potentiometer 90. The use of the selector switch and the potentiometer makes the user interface simple. As such, computer control and, for example, adjustment taking place through a display, would also be possible.

Figure 8b shows an example of the alignment between the front wheels 38 of the tractor 28 and the rotating frame 24 of the front lifting device 10, when the tracking selector is in the state shown in Figure 8a. The front wheels 38 and the rotating frame 24 are turned in the same direction at the same angle, as the alignment of the rotating frame depends on the alignment of the front wheels. In basic state 2, the ratio of the turning of the rotating frame relative to the front wheels is regulated using a potentiometer 90. If, in basic state 2, the potentiometer 90 is rotated clockwise to the maximum value of the selector scale (Figure 8a) , the rotating frame 24 will follow the front wheels being in the same angle as them.

Figure 9a shows the tracking selector, the selector switch 92 in which is used to select basic state 2 for use. The potentiometer 90 is rotated to half-way on the selector scale.

Figure 9b shows an example of the alignment between the front wheels 38 of the tractor 28 and the rotating frame 24 of the front lifting device 10, when the tracking selector is in the state shown in Figure 9a. The front wheels 38 and the rotating frame 24 are turned in the same direction, and the alignment of the rotating frame depends on the alignment of the front wheels. As the selector switch 92 is rotated to basic state 2 and the potentiometer 90 is rotated to half-way on the selector scale (Figure 9a), the rotating frame follows the front wheels at half of their angle. In other words, the rotating frame turns half of what the wheels turn. For example, when the wheels turn 26 , the rotating frame turns 13 .

Figure 10a shows the tracking selector, the selector switch 92 in which is used to select basic state 2 for use. The potentiometer 90 is rotated to its counterclockwise extreme position on the selector scale. 5

Figure 10b shows an example of the alignment between the front wheels 38 of the tractor 28 and the rotating frame 24 of the front lifting device 10, when the selector switch is in the state shown in Figure 10a. The front wheels 38 are turned as

10 shown in Figures 8b and 9b, but the rotating frame is parallel to the direction of the tractor's chassis. Even though, in basic state 2, the turning of the rotating frame affects the turning of the wheels, when the potentiometer 90 is in the extreme counterclockwise position on the selector scale (Figure

15 10a), the rotating frame is parallel to the tractor's chassis.

The selector scale of the potentiometer shown in Figures 8a - 10a is linear and the selector switch 92 is in the basic state 2. When the potentiometer 90 is at the extreme counterclockwise

20 position of the selector scale, the value given by the potentiometer 90 is 0 %. When the potentiometer 90 is, in turn, at the extreme clockwise value, the value given by the potentiometer is 100 %. When the potentiometer 90 is half-way on the linear selector scale, the value given by the potentiometer is

25 50 %. The selector switch is used to select that the rotating frame will follow the steering of the tractor, more specifically, of the front wheels. The value given by the potentiometer depicts how the rotating frame will follow the turning of the tractor .

30

The stepped regulating element belonging to the selector switch shown in Figures 7a - 10a can also be used to select the basic states 3 and 4. In these basic states, the turning of the rotating frame is affected by the turning of the tractor. The

35 values given by the potentiometer differ in these applications to those above. The values can be, for example, 0 - 200 %, in which case the rotating frame will turn twice as much as the

tractor turns. In addition, when the basic state changes, the scale of the potentiometer can become non-linear.

In Figure 11, a rear mower 96 is attached to the tractor's 28 rear lifting device 94. A front mower 98 is attached, in turn, to the front lifting device 10. The front mower 98 and the rear mower 96 are attached in such a way that they can be used to mow the widest possible area. The rear mower 96 is attached to the rear lifting device 94 in such a way that it mows hay from the rear wheel 40 outwards. The mowing width of the rear mower can be, for example, 2,5 - 3,5 m. There is no benefit in trying to use the rear mower to mow hay behind the rear wheel, as the hay will have been crushed there. For its part, the front mower 98, the width a of which can be, for example 2,5 - 3,5 m, is attached in such a way that it mows the hay in front of the tractor 28. When the tractor is driven straight, even a front mower according to the prior art will have no problem in mowing the hay effectively, but an unmown area 100 will remain in the curves. The front lifting device 10 according to the invention, which includes a rotating frame 24 attached to a frame component by a vertical shaft 22, will permit the front mower 98 to follow a new mowing line 102.

The examples described above are only some of the several benefits that can be achieved using the front lifting device and method according to the invention.