FRONT END LOADER

Abstract: Front end loader intended to be mounted on tractors and functioning in such a way that the length of the lift­ ing arms (13) can be increased or reduced in connection with an alteration of the elevation of the lifting arms (13). The device includes a lifting arm (13) which is bent in angle and consists of a front end part (8) and a rear end part (9). These parts are moveable in relation to each other, thus permitting an elongation or a shortening of the lifting arm (13). The alternation of the length of the lifting arm (13) permits an adaption to different ap­ plications such when there are special requirements regarding lifting height or loading capacity.

Description: FRONT END LOADER TECHNICAL FIELD The invention relates to a front end loader intended to be mounted on tractors and similar vehicles and intended to be used e.g. as a loading device within agriculture. The front end loader can be equipped with different types of special devices which can be used e.g. for the handling of pallets, round or cylindrical bales and large sacks. The invention relates more specifically to a front end loader with arms with variable length, which permit an adaptation to different kinds of applications. PRESENT ART Front end loaders of the mentioned type are earlier well known and have been used to a large extent within agriculture. An increase of the length of the arms of earlier known front end loaders implies, however, that the load is moved forward in relation to the tractor, when the arms are at their lowest position. The loading device is thus exposed to huge strain when the tractor is driven carrying a load with elongated arms at their lowest position. In order to reduce the strain when using hitherto known front end loaders, it will be necessary to reduce the maximum load. The minimum length of the arms of hitherto known designs of front end loaders is furthermore limited by the space available when the arms are at their lowest position when the tractor is moved. The arms of front end loaders according to present art can be elongated in order to reach higher. The load will thus be placed far away in front of the tractor when the arms are in their driving position, i.e. their lowest position. This is a considerable disadvantage with front end loaders of known designs, specially when the tractor is driven on an uneven surface at relatively high speed, due to the fact that dynamic strain on the front end loader and on the tractor is considerable under such conditions. When using front end loaders according to present art, it is necessary to choose the length of the arms either according to the height to be reached or according to the load required. In the first case the length of the arms must be considerable and if the front end loader is designed in such a way that the arms can be elongated the maximum length of arms is chosen. This implies however the disadvantage that the loading capacity is limited and that the front end loader in its driving position iXe. in its lowest position, has the load placed far away in front of the tractor which implies huge dynamic strain on the tractor and on the front end loader when driving on an irregular surface. If the length of the arms is chosen for a maximum loading capacity, the shortest arm length should be chosen. This implies, however, that the height that can be reached will be limited. DISCLOSURE OF THE INVENTION It is an object of the invention to provide a front end loader with which the above mentioned disadvantages and limitations are eliminated. The front end loader according to the present invention is characterized by being provided with arms with variable length. The front end loader is furthermore provided with organs which achieve a length variation of the arms which is a function of the height position of the arms. The front end loader according to the present invention is designed in such a way that the arms have their shortest length when they are at their lowest position. The above mentioned organs are adjusted in such a way that their length increases if the arms are lifted, if a considerable height should be reached. In those cases when it is a primary purpose to achieve a considerable loading capacity the above mentioned organs are adjusted in such a way that the arms are shortened whilst they are lifted. The organs, which guide the length of the arms in such a way that the arm length is a function of the height of the arms, may furthermore be adjusted into one or several intermedium positions in such a way that a reduced increase of length or reduced reduction of length is obtained when lifting the arms. It is also possible to adjust the organs in question in such a way that the length of the arms is not changed when the arms are lifted. Further characteristics and advantages with the present invention will become apparent from the following description of a preferred embodiment and from the following claims. SHORT DESCRIPTION OF THE FIGURES In the following description of a preferred embodiment reference will be made to the following figures. Fig. 1 shows a side view of the front end loader, Fig. 2 is a side view, which shows how the front end part of the arms is connected to the rear end part of the arm, and Fig. 3 is a cross-section A-A in Fig. 2. DESCRIPTION OF A PREFERRED EMBODIMENT The arm belonging to the front end loader is bent in angle and has been designated with 13 on Fig. 1. The arm 13 can be elongated and consists thus of two parts, namely a rear end part 9 and a front end part 8, which is bent in angle. The rear end part 9 of the arm has a mainly tubular form with rectangular section. The rear end part 9 of the arm surrounds and encloses the rear part of the front end part 8 of the arm, which is bent in angle. Fig. 2 shows how the front end part 8 of the arm is connected to the rear end part 9 of the arm. The rear end part 9 of the arm is equipped with a rear support roller 14 and the front end support roller 15. The support rollers 14, 15 take up the forces required to carry the weight of the front end part 8 of the arm and the load. The support rollers 14, 15 serve the purpose of reducing friction to a minimum when the front end part 8 of the arm is moved inwards and outwards in the rear end part 9 of the arm 13. On Fig. 2 an ear 16 is shown, which is intended for the connection of the front end part of a piston belonging to a hydraulic cylinder. The arm 13 is lifted and lowered by means of the above mentioned hydraulic cylinder. On the front end part 8 of the arm there is a fastening device 11, which is used to attach one of the ends of a link rod 1. The other end of the link rod 1 can be attached either to two attachment points 3, 4, which are located on a support 10 or to an attachment point 17 on the rear end part 9 of the arm 13, which is bent in angle. When the rear end part of the link rod 1 is attached to the attachment point 17 on the straight part 9 of the arm 13 there is no displacement of the front end part 8 of the arm 13 in relation to the rear end part 9 when the arm 13 is lifted or lowered. The curves I, II and III on Fig. 1 show how a fore end attachment point 6 on the front end part 8 of the arm is displaced when the arm 13 is lifted or lowered. The attachment point 6 is used to attach special devices for handling of loads such as forks for handling of pallets. When the rear end of the link rod 1 is attached to the attachment point 17 there is no relative movement between the front end part 8 of the arm 13 and the rear end part 9 of the same arm. The attachment point 6 will then move according to the curve which has been designated II when the arm 13 is lifted or lowered. The attachment point 6 will be in such a position that the load will be placed as near to the tractor as possible, when the arm 13 is in its lowest position. When driving the tractor, the arm will generally be placed in its lowest position. The dynamic strain in connection with the movement of the tractor will be reduced to a minimum, if the load is placed as much rearwards as possible. In those cases when maximum lifting height should be achieved, the rear end of the link rod 1 is attached to the attachment point 4. The arm 13 will then be elongated when the arm 13 is moved upwards and the attachment point 6 will describe a curve corresponding to the one designated with III on Fig. 1, when the arm is lowered or lifted. If the rear end attachment point of the link rod 1 is moved to the attachment point 3, the arm 13 will be shortened when the arm 13 is lifted. The attachment point 6 will then describe a curve I in connection with a upwards or downwards movement of the arm 13. The choice of attachment points for the rear end of the link rod 1 thus permits a choice among different functional relations between the height position of the arm 13 and its length. If further attachment points are provided for the attachment of the rear end of the link rod 1, there will be further possibilities of adjustment to other functional relations between the height position of the arm 13 and its length. The same functional relation which has been obtained by means of the link rod 1 can also be obtained if the relative movement between the front end part 8 of the arm 13 and its rear end part 9 is achieved by means of a hydraulic cylinder which is controlled in some adequate way. Further modifications of the described embodiment are possible within the intended scope of the present invention. Such modifications will thus not imply that the modified device will trespass the limits of the claims stated in the following pages.

Claims: CLAIMS 1. Front end loader adapted to be mounted on tractors mainly consisting of a pair of parallel arms, which are bent in angle in such a way that an obtuse angle is formed by the straight parts of each arm, said arms being simultaneously pivotable around a pivoting axis located at one end of the arms, said pivoting axis being perpendicular to the planes defined by the straight parts of each individual arm, c h a r a c t e r i z e d thereby that the front end loader is equipped with organs which permit the straight parts of the arms which are located closest to the pivoting axis automatically to be elongated or shortened successively and continuously when the opposite end of the arms located farthest away from the pivoting axis are lifted. 2. Front end loader according to claim 1, c h a r a c t e r i z e d thereby that the mentioned organs which permit the elongation of the arms can be adjusted in such a way that several different functional relations are obtained between the length of the arms and their elevation position. 3. Front end loader according to claims 1 or 2, c h a r a c t e r i z e d thereby that the mentioned organs which permit the elongation of the arms consist of a link rod with its front end attached to a fore end part of the lifting arm and its rear end attached to a support or a similar part which is not moveable in relation to the tractor. 4. Front end loader according to any of the claims 1-3, c h a r a c t e r i z e d thereby that the rear end of the link rod, which constitutes the organ for elongation and shortening of the arm, can be attached to three different points which gives three different functional relations between the length of the arms and its elevation position.

Inventors: MELIN, KARL HARVID
Applicants: MELIN, KARL HARVID
Application year: 1982
Main classification: A01D87
IPC codes: E02F3, A01D87