A rotation device for lifting apparatus

Abstract

 The rotation device for lifting apparatus, especially for cranes mountable on vehicles, comprises a hydraulic cylinder (2) which exhibits a stem (3), solidly connected to a fixed base (4), on which a rotating column (1) of the lifting device is mounted. The body (5) of the hydraulic cylinder (2) is constrained to translate with respect to the fixed base (4) and is externally provided with helical guides (6) in which organs (17) predisposed on a crown (7) engage. The crown (7) is coupled on the external surface of the body (5) and solidly constrained on the column (1).

Description

[0001] Especially, but not exclusively, lifting apparatus such as cranes, whether articulated or provided with a single arm, predisposed for mounting on vehicles, boats or fixed positions, exhibit a basic structure which is fixed on the bearing structure, for example the back of a truck, on which a rotating vertical column bearing the arm is constrained. The rotation of the crane is realized by producing the rotation of the column with respect to the fixed base.

[0002] A known device for realizing the rotation is constituted by a gearing fixed on the rotating part and a worm screw, connected to the fixed part, which is generally driven by an orbital hydraulic motor. This system is normally used for limited-capacity cranes which are possibly not used very frequently, because the gear-worm screw coupling requires coupling precision which could not be respected under very stressful working conditions, where relevant deformation takes place.

[0003] The prior art teaches a further system wherein the rotation function is delegated to a coupling of a gearwheel keyed on the rotating part itself with a rack powered by a hydraulic cylinder. This device, very frequently adopted, has however the drawback of requiring racks and therefore cylinders of considerable mass.

[0004] Finally, for high-capacity lifting devices, a system using a thrust bearing is used, which internally thereof houses a gearing through which it meshes with a pinion driven by a group comprising a motor, a gear reducer and a brake.

[0005] Some of the known realisations exhibit the characteristic of being useful only on large cranes.

[0006] Other realisations, even though suitable for small cranes, have the drawback of being considerably massive.

[0007] The present invention, as it is characterised in the claims that follow, obviates the lacks and drawbacks in the prior art by providing a rotation device for lifting apparatus in general and in particular for very simple and compact cranes, and 25is therefore suitable for small cranes.

[0008] An advantage of the invention is that it can be contained internally of the crane column.

[0009] Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of an embodiment of the invention, illustrated in the form of a non-limiting example in the accompanying drawings, in which:

figure 1 is a schematic section made in a vertical axial plane;

figure 2 is a schematic section made along line II-II of figure 1;

figure 3 is a schematic section made along line III-III of figure 1.

[0010] With reference to the figures of the drawings, 1 denotes a rotating column of a lifting apparatus constituted for example by an articulated crane for mounting on vehicles. The column 1 bears the articulated or single-shaft arm (not included in the drawings) of the apparatus. The column 1 is rotatably coupled on a fixed base 4 which is fixed to the frame 10 of the vehicle bearing the apparatus. A hydraulic cylinder 2 is arranged internally of the fixed base 4, a stem 3 thereof being solidly constrained to an inferior part of the fixed base 4. In particular the stem 3 is stirruped and/or hinged in such a way as to adapt unproblematically to flexional deformations to which the inferior part of the apparatus is inevitably subjected during use. The body 5 of the hydraulic cylinder 2 is vertically translated with respect to the fixed base 4 due to coupling of a projecting radial pivot 8, solidly constrained to the body 5, which engages in a straight internal vertical channel 9 fashioned in the fixed base 4.

[0011] In the present embodiment, four parallel helix guides or channels 6 are made at the external cylindrical surface of the body 5. A crown wheel 7 is arranged at the top of the fixed base 4, which 15 crown 7 is coupled, with a predetermined play, on the external surface of the body 5 and is provided with four angularly equidistanced organs 17 engaging slidably in the four helical guides 6. The crown 7 is solidly constrained to the column 1. With the above-described device a rotation can be imposed on the crown 7 and thus on the column 1 with respect to the fixed base 4, simply by causing axial sliding of the body 5 of the hydraulic cylinder 2. Starting from the configuration of figure 1 and injecting pressurised oil into the hydraulic cylinder 2, the body 5 moves upwards, vertically translated by the coupling between the radial pivot 8 and the vertical channel 9 provided in the fixed base 4. The vertical translation of the body 5 transforms, by effect of the coupling of the organs 17 in the helical guides 6, into a rotation of the crown 7 and thus of the column 1. The rotation direction of the column 1 is determined by the translation direction of the body 5 with respect to the fixed base 4. The vertical displacement of the body 5 occurs freely, by effect of the free coupling of the body 5 with the crown 7, and due to the fact that above the fixed base 4, the body 5 can freely enter in the column 1, which is hollow.

[0012] In this way, by a hydraulic command actuating the movements of the hydraulic cylinder 2, the column 1 of the crane can be rotated. The rotation device is characterized in that it has practically no external mass, as it is contained internally of the fixed base 4 and the column 1.

[0013] The device guarantees durability and a good resistance to deformation forces which are inevitably produced on the column 1 in loaded positions.

Claims

1. A rotation device for lifting apparatus of a type comprising a column (1) rotatable about a vertical axis thereof on which an articulated or single-shaft arm is arranged, characterized in that it comprises:

a hydraulic cylinder (2) exhibiting a stem (3) an end whereof is constrained to a fixed base (4) of the apparatus, on which fixed base (4) said column (1) is rotatably mounted, and a body (5) whereof is constrained to perform translation movements with respect to said fixed base (4);

means for transforming translation movements of said body (5) into rotation movements of said column (1).

2. A device as in claim 1, characterized in that said means for transforming comprise:

at least one helical guide (6) arranged coaxially to said body (5) and at an external surface thereof;

a crown (7) coupled on the external surface of said body (5) and provided with at least one organ (17) which slidably engages in said at least one helical guide (6);

said column (1) being solidly connected to said crown (7).

3. A device as in claim 2, characterized in that it comprises a plurality of helical guides (6) arranged on the external surface of the body (5) of said hydraulic cylinder (2); a like plurality of organs (17) being provided on said crown (7) and engaging one-for-one in said plurality of helical guides (6).

4. A device as in claim 1, characterized in that said body (5) is constrained to translate axially with respect to the fixed base (4) by a coupling of at least one projecting radial pivot (8) which engages in at least one straight vertical channel (9) fashioned in said fixed base (4).

Drawing