CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application of utility model no. 202020000001774 filed on 21/04/2020, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present innovation relates to a grab bucket excavator.

In particular, the present innovation relates to a grab bucket excavator of the type comprising a self- propelled vehicle, for example a tracked self-propelled vehicle; a grab bucket comprising, in turn, two shovels movable with respect to each other between an open position and a closed position; a lifting device fitted on the self- propelled vehicle for lowering and lifting the grab bucket; and a hydraulic drive device for moving the shovels between the open position and the closed position.

BACKGROUND ART

Generally, the lifting device comprises a pair of pulling ropes, which are hooked on one side onto the bucket and on the other side onto respective winding rollers fitted on the self-propelled vehicle, and are wound around at least two return pulleys fitted at a free upper end of an upright extending upwards from the self-propelled vehicle.

The hydraulic drive device normally comprises at least one actuator cylinder connected to the shovels and at least one flexible pipe, which supplies a fluid under pressure to the actuator cylinder, and is hooked on one side onto the actuator cylinder and on the other side onto a winding roller fitted on the self-propelled vehicle.

Since the known grab bucket excavators of the type described above are used for making perforations having a relatively high depth, the flexible pipe has, inside the perforation, a relatively long length subjected to a relatively high axial traction force generated by the grab bucket and by the winding roller of the flexible pipe. The known grab bucket excavators of the type described above have some drawbacks mainly deriving from the fact that the flexible pipes currently used have a relatively high radial resistance to the fluid under pressure but a relatively reduced axial resistance to the traction. DISCLOSURE OF INVENTION

The object of the present innovation is to provide a grab bucket excavator which is exempt from the drawbacks described above and which is simple and cost-effective to manufacture .

According to the present innovation, a grab bucket excavator is provided as claimed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present innovation will now be described with reference to the accompanying drawings, which illustrate a non-limiting embodiment example thereof, wherein:

Figure 1 is a schematic perspective view, with parts removed for clarity, of a preferred embodiment of the grab bucket excavator of the present innovation; and

Figure 2 is a sectional schematic view of a detail of the grab bucket excavator of Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figure 1, reference numeral 1 indicates, as a whole, a grab bucket excavator comprising a self-propelled vehicle 2, in this case a tracked vehicle, provided with an operator cab 3 and with an upright 4 extending upwards from the self-propelled vehicle 2.

The excavator 1 further has a perforation device 5 comprising a supporting frame 6 and a bucket 7 provided with two shovels 8 rotatably coupled to the frame 6 for rotating, with respect to the frame 6 and under the thrust of a hydraulic drive device 9, between an open position

(Figure 1) and a closed position (not illustrated).

The excavator 1 is further provided with a lifting device 10 for lifting and lowering the device 5.

The device 10 comprises, in this case, two pulling ropes 11, which are hooked on one side onto the frame 6 and on the other side onto respective winding rollers 12 fitted on the vehicle 2, and are wound around at least two return pulleys 13 fitted at a free upper end of the upright 4.

The device 9 comprises at least one known and not shown actuator cylinder, which is fixed to the frame 6, has an output rod connected to the shovels 8, and is operated by a fluid under pressure supplied along a pair of flexible pipes 14, which are connected on one side to the actuator cylinder (not illustrated) and on the other side to respective winding rollers 15 fitted on the vehicle 2, and are wound around respective return pulleys 16 fitted along and at the free upper end of the upright 4.

According to what illustrated in Figure 2, each pipe 14 has a longitudinal axis 17, and comprises, in this case: an inner tube 18, which is made of polymeric material, is designed to ensure the seal of the pipe 14 to the fluid under pressure, and has an inner diameter comprised between 5 mm and 105 mm; an outer tube 19, which is made of polymeric material, and is designed to protect the pipe 14 from the atmospheric agents, from the abrasion, and from the attack of chemical substances; e six reinforcement layers 20, which are interposed between the inner tube 18 and the outer tube 19, overlap each other, and each one comprises a respective plurality of wires made of metallic material.

The layers 20 are helically wound around the axis 17 in an alternated manner in two windup directions opposite to each other.

The two layers 20 (in the following indicated by 20a) adjacent the outer tube 19 are wound around the axis 17 with respective windup angles a, which are comprised between 36° and 54°, in particular are equal to 45°, and are equal to or differ from each other.

The remaining four layers 20 (in the following indicated by 20b) are wound around the axis 17 with respective windup angles b, which are comprised between 48° and 62°, in particular are equal to 54°44', are equal to or differ from each other, and differ from the angles a.

With regard to what described above, it should be specified that: when the angles are equal to each other and the angles b are equal to each other, the difference between the angles and the angles b is comprised between 2° and 15°; when the angles differ from each other and the angles b differ from each other, the difference between the greatest angle and the smallest angle b is comprised between 2° and 15°. The pipe 14 further comprises a plurality of intermediate layers 21, each of which is interposed between two adjacent layers 20 for ensuring the adhesion between the layers 20, and is made of polymeric material. The pipe 14 further has a consolidation layer 22, which is made of textile material, and is fitted on the tube 18 for ensuring a relatively high resistance to the tube 18 both during the manufacturing of the pipe 14, and at the coupling zone of the pipe 14 to the actuator cylinder (not illustrated).

The pipe 14 further comprises a further intermediate layer 23, which is totally analogous to the layers 21, and is interposed between the layer 22 and the adjacent layer 20b so as to ensure the adhesion between the layer 22 and the layer 20b.

Of course, the inner tube 18, the outer tube 19, the reinforcement layers 20, the intermediate layers 21, 23, and the consolidation layer 22 have a length equal to a length of the pipe 14. According to some variants not illustrated, the number of layers 20b is different from four, for example equal to six or eight.

The excavator 1 has some advantages mainly deriving from the fact that the layers 20b of each pipe 14 cooperate with the relative tube 18 for ensuring to the pipe 14 a relatively high radial resistance to the fluid under pressure and that the layers 20a ensure to the pipe 14 a relatively high flexibility, elasticity and, thus, an axial resistance to the traction. The axial resistance to the traction of the pipes 14 is further improved by the difference of at least 2° existing between the angles and the angles b.