The present invention relates to an implement coupling for excavators or loaders and of the type described in the introductory part of claim 1.

Implement couplings of this type is used to be able to shift quickly and easily between different implements, for instance between excavator buckets with different width or between excavator and loader bucket. The implement coupling may comprise an either manually operated shift mechanism requiring that the operator leaves the cabin, or a remote controlled shift mechanism, which may be operated from the cabin, for instance by means of a hydraulic hand pump.

At both manually and hydraulically operated implement couplings a good security is required against failure and/or mis-operating of the locking function of the shift mechanism of the implement coupling.

The purpose of the invention is to provide an implement coupling for excavators or loaders of the type mentioned in the introducty part, and which by simple provisions makes it possible to obtain extraordinary good security against unintended disengage¬ ment of the implement.

The implement coupling according to the invention is distinctive in that the swing arm mechanism opposite the locking splice comprises a basic joint being pivotally arranged on a central, fixed pivot axle, and said basic joint via a bent axle in a distance from the pivot axle being pivotally connected with the locking splice by means of an intermediate arm, that the basic joint has a projecting arm part, which is adapted to be swung into a position mainly parallel with the intermediate arm, so that an end part of the projecting arm part is placed behind the locking splice, when this is in lock engagement with the hook-shaped locking part of the implement, and when said bent axle is placed in a dead center position at the opposite side of the connecting line between the locking splice and the pivot axle, and that the basic joint for operation of the shift mechanism furthermore is connected with a manual operating handle and/or a hydraulic activiation cylinder. By simple technical provisions extraordinary good security against unintended disengage¬ ment of the implement by releasing the locking function of the coupling is hereby obtained.

Appropriately the implement coupling according to the invention is such provided that a pressure cylinder with a piston rod, a piston and a powerful pressure spring are inserted in said intermediate arm.

When the implement coupling according to invention is adapted to be manually operated it appropriately may be such provided that the operating handle is connected with the projected arm part at the side opposite the intermediate arm, and that in con¬ nection with the operating handle is a pivoting locking pawl being adapted to lock the operating handle, when it is swung in parallel with the intermediate arm, that is in the locking position of the implement coupling.

While the implement coupling according to the invention, when it is adapted to be hy- draulically operated, advantageously may be such provided, that a piston rod of the hydraulic activation cylinder is connected with an activiation arm part of the basic joint projecting from the latter opposite the projecting arm part, that is at the side opposite of the intermediate arm, which by means of said end part engage behind the locking splice, when the activation arm part is led to the rear by the piston rod, and that the hydraulic activation cylinder is provided with an internal pressure spring affecting the piston rod in the direction towards the activation arm part, that is maintaining the locking function of the implement coupling, if the hydraulic pressure should disappear.

The invention is explained in more detail in the following with reference to the drawing, in which: -

Fig. 1 shows a plane partial view - seen from above - of an embodiment for an imple¬ ment coupling according to the invention, while

Fig. 2 shows a side view - partly in section - of the implement coupling shown in Fig. 1.

The shown implement coupling 2 consists of two parallel bearing plates 4 with bearings 6 and 8 by means of which the implement coupling 2 is intended to be mounted at an outer end of an excavator arm or a loader arm respectively to be connected with a yoke for a hydraulic cylinder for swing of the implement coupling respectively the imple- ment, for instance an excavator bucket or a loader bucket 10 (Fig. 2).

The implement coupling 2 is at an end provided with hook-shaped connecting parts 12 being adapted to grasp around fixed connecting dowels at each its side of the imple¬ ment, for instance the excavator bucket 10, which at the opposite side is provided with a hook-shaped locking part 16, which is intended to be lead into the implement coupling 2 through a central side opening 18.

When the connecting parts 12 are lead over the connecting dowels 14 the hook-shaped locking part 16 is lead through the central side opening 18 and a locking splice 20, which is displacable arranged between gliding rails 22 of the implement coupling 2, is lead forward into locked position with the hook-shaped locking part 16, which is carried out by swinging a basic joint 24 either manually by means of a projecting arm part 26 and an operating handle 28 or hydraulically by means of an activation cylinder 30 and an activation arm part 32, so that the locking splice 20 may be lead forward by means of an intermediate arm 34.

The intermediate arm 34, which comprises a pressure cylinder 36 with a piston rod 38 and an enormous pressure spring 40, is inserted between the locking splice 20 and a bent axle 42 of the basic joint 24. The bent axle 42 is placed in a distance from a fixed pivot axle 44 for the basic joint 24, so that the springy intermediate arm 34 may be dis- placed inwards passing the direct connecting line between the pivot axle 44 and a turning point 46 between the locking splice 20 and the intermediate arm 34 to a dead center position 48, where and end part 50 of the projecting arm part 26 is swung further inwards to a position just behind the locking splice 20, that is that extraordinary big security is obtained that the locking splice 20 unintended may be lead out of the locking engagement with the hook-shaped locking part 16.

The hydraulic activation cylinder 30 may appropriately be placed at the opposite side of the implement coupling 2, so that the activiation cylinder 30 by means of a pistion rod 52 may affect the activation arm part 32 and with that the basic joint 24 for releasing the locking engagement between the locking splice 20 and the locking part 16. Also in this situation the displaced bent axle 42 is used for establishment of a self-locking dead center position, where extra good security towards unintended disengagement of the locking engagement between the locking splice 20 and the locking part 16 by means of the projecting arm part 26 also is obtained, of which arm part an end part is placed just behind the locking splice 20. The activation cylinder 30 is further provided with an internal pressure spring 54, which affects the piston rod 52 in the direction towards the

activation arm part 32, and which thereby assists to maintain the locking function of the implement coupling, if the hydraulic pressure should disappear.

Regardless the implement coupling according to the invention is adapted to be manually or hydraulically operated extraordinary good security against unintended disengagement of the locking engagement between the locking splice 20 and the locking part 16 is ob¬ tained, namely because of the following:

Manual:

A: Intermediate arm 34 comprises pressure cylinder 36

B: Intermediate arm 34 fixed in dead center position 48

C: End part 50 of projecting arm part 26 placed behind the locking splice 20 D: Short free length of stroke of the pressure cylinder 36

£: Operating handle 28 locked in locking position.

Hydraulic:

A Intermediate arm 34 comprises pressure cylinder 36 B Intermediate arm 34 fixed in dead center position 48 C End part 50 of projecting arm part 26 placed behind the locking splice 20 F Activation cylinder 30 comprises pressure spring 54 G Projecting arm part 26 functions as signal marker