Arrangement for implement and implement holder

Abstract

 An arrangement for implements and implement fixtures (11) for excavators, tractors and similar, comprising an implement with two principally parallel shafts (15, 17) arranged to be gripped by an implement fixture (11) arranged on an arm of the excavator, tractor or similar. At least one of the shafts (15, 17) arranged in the implement is designed with a surface (15a, 17a) that is a part of a circularly cylindrical surface and a principally tangential surface (15b, 17b) that adjoins this, and the implement fixture (11) in a corresponding manner comprises a fork (14) with a surface that is a part of a circularly cylindrical surface and a principally tangential surface (14b) adjoining this.

Description

[0001] The present invention concerns an arrangement for an implement and an implement fixture for excavators, tractors and similar, which arrangement is arranged such that it is possible for an implement to be gripped by the implement fixture and held fixed in a safe manner by this fixture during work.

[0002] Excavators are now normally provided with an implement fixture between the excavator arm and the bucket or other implement that is supported by the excavator arm in order to make possible a simple exchange of the bucket or other implement. The possibility of rapidly being able to switch between, for example, a narrow bucket, broad bucket, peg tooth, cutting wheel, gripping bucket, hydraulic hammer, vibrator, brush, etc., make the use of an excavator significantly more efficient.

[0003] Several different types and designs of implement fixtures for such exchange of implements have long been manufactured. Given the amount of different tools and implements that are now available for excavators, it has become particularly pertinent that the exchange between such tools/implements, hereafter referred to solely as "implements", should be simple and rapid. The implement fixture is to achieve a secure connection that is free of play, and that has secure locking, between the implement and the arm of the excavator. It must be easy also for the driver to capture and release an implement and to be able to lock it fixed to the arm, without leaving the cabin and with the aid of the range of movement of the machine.

[0004] In order to be able to carry out such a gripping activity of the implement, the implement fixture has been designed with the fundamental principle that it comprises a fork that is placed around a shaft of circular cross-section on the implement, after which the fork of the implement fixture is pivoted around the shaft such that the implement is captured and lifted, whereby the weight and centre of gravity of the implement achieve a pivoting of the implement such that also a second shaft on the implement can be gripped by the implement fixture, and such that a locking mechanism of this second shaft can then lock the implement to the implement fixture.

[0005] An implement fixture must be dimensioned such that it is able to transfer the force of play that arises in the excavator arm, link arm and fixture; the force between the fixture and the attachment module for the implement; and finally the external force applied to, for example, the tooth tip of a bucket.

[0006] The implement fixture contributes additional weight, which has a negative influence on the lifting capacity and energy consumption of the excavator, and on its maintenance costs.

[0007] It is common also that what is known as an "intermediate pivot piece" or "intermediate rotor piece" is arranged at the implement fixture of the machine, and this intermediate piece has a further implement fixture to which the bucket or other implement is attached. Further additional weight arises as a result of this.

[0008] It is therefore of considerable significance that the implement fixture units, i.e. the implement fixture and the fixture parts of the implements, have design solutions that give a low weight while at the same time giving high durability and high resistance to wear. It is important also that an implement fixture can be designed with as low an added height as possible. The dimension of a bucket cylinder is normally determined for a particular bucket that is to be mounted on the excavator arm, in order to obtain an excavation force of an appropriate magnitude at the tooth tip of the bucket. If an implement fixture, and possibly also intermediate parts with further implement fixtures, is or are mounted on the excavator arm, the excavation force will be reduced as a consequence of the increase in the distance between pivot point and tooth tip. This leads also to increased consumption of energy.

[0009] In order to obtain sufficient durability and a long life, however, it has until now been customary to increase the dimensions of the shafts of the implement, which in turn has led to increased dimensions of also the implement fixture, which is directly contrary to the wishes with respect to weight and energy efficiency.

[0010] It is therefore one purpose of the present invention to achieve a new arrangement for implements and implement fixtures such that it will be possible to reduce the dimensions of the shafts of the implement, and in this way possible to reduce also the dimensions of the implement fixture, in order to increase the efficiency of the excavator, and to achieve this while maintaining, or even increasing, not only the durability but also the resistance to wear.

[0011] The purpose of the invention described above is achieved with an arrangement according to the invention, comprising an implement with two essentially parallel shafts arranged to be gripped by an implement fixture, where at least one of the shafts arranged in the implement is designed with a surface that is a part of a circularly cylindrical surface and a principally tangential surface that adjoins this, and where the implement fixture in a corresponding manner comprises a fork with a surface that is a part of a circularly cylindrical surface and a principally tangentially directed surface adjoining this.

[0012] According to one preferred embodiment of the invention, also the second shaft of the implement is designed with a surface that is a part of a circularly cylindrical surface and a principally tangential surface that adjoins this.

[0013] According to a further preferred embodiment of the invention, the shafts are designed such that the surface that is a part of a circularly cylindrical surface covers approximately 180°, with the principally tangential surface further extending from one end of the surface that is part of a circularly cylindrical surface.

[0014] The invention will be described in more detail below in the form of an embodiment and with the aid of the attached drawings, where Figure 1 shows a side view of an implement fixture according to the prior art technology connected to two shafts on an implement (not shown in the drawing), Figure 2 shows a corresponding side view showing how the distribution of force acting on the load-bearing shaft is normally distributed, Figure 3 shows a side view of an implement fixture connected to shafts according to the arrangement according to the invention, Figure 4 is a detailed view of a part of the arrangement in Figure 3 showing a part of a fork of the implement fixture and the shaft attached to it, Figure 5 shows in a manner corresponding to Figure 2 the normal appearance of the distribution of force for the arrangement according to the invention, and Figure 6 shows a plan view of the normal design of an implement fixture.

[0015] Thus, Figure 1 shows a side view of an implement fixture 1 according to prior art technology. Such an implement fixture is mounted at the end of an arm of an excavator, tractor or similar. The implement fixture has at its upper part two attachment shafts 2 and 3, by which the implement fixture 1 is attached to the arm (not shown in the drawings) in a manner that allows it to pivot, and to a cylinder arrangement (also this not shown in the drawings), with the aid of which it is possible to set the implement fixture 1 at an angle relative to the arm. The implement fixture 1 has further a fork 4 at its lower part, at one end, normally denoted the "forward" end, which fork is capable of gripping a first shaft 5 on an implement. The implement fixture 1 has further a locking peg 6 that can be extended and withdrawn at the opposite end of the lower part, normally denoted the "rear" end. This locking peg can grip in under a second shaft 7 of the implement, when the implement fixture 1 has been placed such that the fork 4 has gripped the first shaft 1 on the implement and been brought into contact with the second shaft 7. The locking peg 6 is operated with the aid of hydraulic pressure from the driver's cabin of the excavator, such that it is possible for the driver to lock and unlock the locking peg as required. It is customary that the shafts 5, 7 of the implement are circularly cylindrical homogenous shafts.

[0016] The resultant force that arises from the load on the implement fixture 1 is distributed normally across the first shaft 5 of the implement during normal use of the implement. The direction and magnitude of the resultant force lie between 90 and 45 degrees to the opening of the fork in the implement fixture 1, which leads to the distribution of force that is shown in Figure 2. It can be seen that only 50 to 70% of the dimension of the shaft is used to transfer the resultant force, and this means that it is necessary to increase the diameter of the shaft by several multiplication factors, which in turn means that it is necessary to increase also the dimensions of the implement fixture, which in turn means that it is necessary to increase the weight, and this leads to increased wear. The load that is transferred between the fork 4 and the shaft 5 is transferred through a very limited area, which leads to severe wear, and play arises rapidly for this reason, which in turn leads to even more rapid wear.

[0017] It is intended to achieve with the new arrangement that is now being proposed according to the present invention a larger area of contact under load between the fork and the shaft in order in this way to reduce the surface pressure between these parts, which reduces wear and the rapid progression of wear from that experienced with a shaft of corresponding dimensions according to the prior art technology. The arrangement according to the invention thus provides the possibility either to transfer greater forces than previously using the same dimension of the shaft or to reduce the dimensions of the shaft.

[0018] Figure 3 shows in a side view corresponding to Figure 1 how an arrangement according to the invention is designed. The implement fixture 11 is, in principle, designed similarly to the implement fixture 1 in Figure 1, but differs with respect to, among other parts, the parts that are in direct contact with the implement. The implement fixture 11 has at its upper part two attachment shafts 12 and 13, with which the implement fixture 11 is connected to the arm and to the cylinder arrangement of the excavator in a manner that allows it to pivot. The implement fixture 11 has at its lower part, at its forward end, a fork 14 that can grip around a first shaft 15 of the implement. Furthermore, the implement fixture 11 has a locking peg 16 that can be extended and withdrawn at the rear end. This locking peg can grip in under the second shaft 17 of the implement, when the implement fixture 11 has been placed such that the fork 14 has gripped the first shaft 15 on the implement and been brought into contact with the second shaft 17. That which significantly distinguishes the design according to the present invention from the prior art technology is that the shafts 15 and 17 are not circularly cylindrical: they demonstrate, at least adjacent to the ends at which they come into contact with the fork 14, a surface 15a and 17a that is a part of a circularly cylindrical surface and that adjoins a surface 15b and 17b that is principally tangentially directed and that extends away from the part of the adjoining surface and that is a part of a circularly cylindrical surface. The surface 15b that is principally tangentially directed constitutes the lower surface of a peg 15c that extends at least a distance that corresponds to the width of the fork 14 along the shaft 15 in its longitudinal direction. Figure 4 shows the shaft 15 in greater detail, with a part of the fork 14 also shown. The peg 15c with the surface 15b that is principally tangentially directed on the shaft 15 has an extent that ensures that it extends a considerable distance beyond the centre of the shaft, preferably a distance that corresponds approximately to the diameter of the shaft. The fork 14 has, in a corresponding manner, a support surface 14b against which the surface 15b that is principally tangentially directed on the shaft can be supported, and in this way a greater contact area between the fork 14 and the shaft 15 is achieved. The shaft 17 is designed in the same manner as the shaft 15 but it has its surface 17b that is principally tangentially directed such that it extends in the opposite direction, i.e. away from the shaft 15.

[0019] It is preferable that the surface 15b, 17b of the shafts that is principally tangentially directed is designed such that it is completely plane, but it may alternatively have a curved surface, either somewhat convex or somewhat concave. It is appropriate that also that part of the fork 14 that is intended to make contact with the surface of the shaft that is principally tangentially directed is completely plane, but if the shaft has a curved surface, either somewhat convex or somewhat concave, then the fork has a curved surface, either somewhat concave or somewhat convex, in order to give as tight a contact as possible with the curved surface, either convex or concave, of the surface of the shaft that is principally tangentially directed. This is shown in Figure 4, which shows a part of the fork 14 with the shaft 15, and where the area of the shaft 15 indicated by the arrow A demonstrates a concave curvature, while the fork 14 demonstrates a convex curvature.

[0020] As is shown in Figure 3 and Figure 4, an indentation has been formed in the shaft 15, as also in the shaft 17, above the peg 15c, such that the circularly cylindrical part of the shaft does not pass all the way around and meet the upper surface of the peg. The possibility is in this way created for the complete dimension of the shaft 15 to be less than the diameter of the shaft, if the fork 14 is continued around over the shaft 15 in the direction of the arrow B in Figure 4. It may be a question of a difference of only a few millimetres, but even this makes it significantly easier to grip the shaft 15, 17 with the aid of the fork 14, and also to release the shaft.

[0021] Figure 5, which shows the resultant force that is exerted on the implement fixture 11 according to the invention as it is normally distributed when using the implement, shows that a significantly greater distribution of the forces over the shaft is obtained with the design of the shaft and fork according to the invention. It can be seen that pretty much the complete dimension of the shaft is used to take up the load. With the design of the shaft 15, 17 according to the invention, a shaft for which the diameter amounts to 60 mm obtains a considerably larger area of contact, and thereby larger area for the absorption of force, than that obtained by a shaft according to the prior art of diameter 80 mm. This then leads to the maximal load becoming lower, and this means that the dimension of the shaft 15 can be reduced from that of the shaft 5 according to the prior art. This leads also to the wear becoming lower, and the lifetime of the shaft can increase. Thus the dimensions of the shafts 15, 17 can be reduced with maintained or improved absorption of force and reduced wear.

[0022] Compared with a completely round shaft, a shaft according to the invention with a diameter of 60 mm has the same area of contact as a completely round shaft with a diameter of 150 mm. Thus, this makes it possible to reduce considerably the dimensions, and in particular the added height, of the parts that are components of the arrangement.

[0023] The design of the shafts 15 and 17 according to the invention allows, as has been described above, the dimensions of the actual shafts to be reduced from the previous dimensions, and it also makes it possible to reduce the dimensions of the side plates 18 in which the shafts 15 and 17 are mounted, in particular the height of these plates. These side plates are in turn attached to the implement, normally by being welded directly onto the implement. The design of the shafts 15 and 17 also results in the shafts obtaining a significantly longer area of contact at the area of contact with the side plates 18, due to the protruding pegs, and this means that the connection with the side plates, which is normally achieved through welding, obtains a significantly greater area and thereby greater strength. The weld between shafts and side plates has previously been a weak point. The side plates 18 can even be designed, with the new design of the shafts, so low that the upper part of the shafts 15, 17 protrudes above the side plates 18, as is shown in Figure 5. This leads to the added height being further reduced, as is also the weight of the component parts.

[0024] The side plates 18 and the shafts 15, 17 thus form the connection at the implement, and these parts together are normally referred to as the "gate". It is appropriate that this gate be designed with mirror symmetry, such that the pegs 15c, 17c on the shafts 15, 17, which face - as has been described above - away from each other, are located on the implement in a manner that has mirror symmetry, such that the implement fixture can grip the implement from two different directions, and the implement in this way will be reversible.

[0025] The implement fixture 11 has traditionally been designed as a largely rectangular body such as that seen in plan view in Figure 6, with the forks 14 located in connection with one end of the implement fixture, on each side of the fixture, and with the locking peg 16 located at the other end of the implement fixture, where the width of the implement fixture essentially agrees with the length of the shafts 15, 17 and with the distance between the side plates 18 at the implement. The implement fixture has support surfaces 19 at the end that comprises the locking peg 16, which support surfaces make contact with the upper surface of the shaft 17 when the locking peg 16 is protruding and makes contact with the lower side of the shaft 17 for locking the implement to the implement fixture.

[0026] It is thus possible with an arrangement according to the invention to achieve not only improved fixing between the implement and the implement fixture, and thereby reduced wear and the subsequent increased length of life. The invention also provides the possibility, as has been described above, to reduce the added height of the arrangement, which leads to a reduction in weight, which reduction is achieved at the farthest extent of the active excavating unit. This leads to improved efficiency of the excavator, with a reduced energy consumption and thus a lower impact on the environment. This effect is larger than the effect that can normally be achieved by the fine-tuning of engines.

Claims

1. An arrangement for implements and implement fixtures (11) for excavators, tractors and similar, comprising an implement with two principally parallel shafts (15, 17) arranged to be gripped by an implement fixture (11) arranged on an arm of the excavator, tractor or similar, characterised in that at least one of the shafts (15, 17) arranged in the implement is designed with a surface (15a, 17a) that is a part of a circularly cylindrical surface and an essentially tangential surface (15b, 17b) that adjoins this, and that the implement fixture (11) in a corresponding manner comprises a fork (14) with a surface that is a part of a circularly cylindrical surface and a principally tangentially surface (14b) adjoining this.

2. The arrangement according to claim 1, characterised in that the two shafts (15, 17) of the implement are designed with a surface (15a, 17a) that is a part of a circularly cylindrical surface and an essentially tangential surface (15b, 17b) that adjoins this.

3. The arrangement according to claim 1 or 2, characterised in that the principally tangentially directed surface (15b, 17b) constitutes a lower surface of a peg (15c, 17c) that extends along the shaft (15, 17) in its longitudinal direction.

4. The arrangement according to claim 3, characterised in that the peg (15c, 17c) extend a considerable distance out from the centre of the shaft (15, 17).

5. The arrangement according to claim 3 or 4, characterised in that the shaft (15, 17) above the peg (15c, 17c) is designed with an indentation that extends along the shaft in its longitudinal direction.

6. The arrangement according to any one of claims 1-5, characterised in that the surface (15c, 17c) that is principally tangential on the shaft (15, 17) is arranged solely next to the ends of the shaft (15, 17).

7. The arrangement according to any one of claims 1-6, characterised that the surface (15c, 17c) that is principally tangential on the shaft (15, 17) and the surface (14b) of the fork (14) that is principally tangential are plane surfaces.

8. The arrangement according to any one of claims 1-6, characterised in that the surface (15c, 17c) that is principally tangential on the shaft (15, 17) demonstrates a curved surface that is somewhat concave or convex, and the surface (14b) of the fork (14) that is principally tangential demonstrates a curved surface that is somewhat convex or concave.

9. The arrangement according to any one of the preceding claims characterised in that the shafts (15, 17) of the implement are arranged on the implement in a manner that has mirror symmetry such that they can be gripped by the implement fixture (11) from both directions.

Drawing