Bearing Assembly in a Mobile Hydraulic Crane Telescopic Arm and a Mobile Hydraulic Crane Comprising Such Assembly

Abstract

The present disclosure includes a telescopic bearing assembly capable of withstanding predetermined bending loads and at the same time is fully telescopically extendable, while minimizing a wall thickness (t) in each of tubular bearing sections of an associated telescopic arm. Additionally, the present disclosure includes a mobile hydraulic telescopic crane with a telescopic arm with such an assembly.

Claims

1. A bearing assembly in a mobile hydraulic crane telescopic arm, comprising: at least two tubular bearing sections, which are inserted within each other and telescopically moveable in a controlled manner in an axial direction, wherein an outer tubular bearing section having a pre-determined length and an inner tubular bearing section having a pre-determined length L.sub.1 are complementary in shape in their transversal cross-sections, having a minimal overlapping length L.sub.9 and approximately uniform spacing along a complete circumference, wherein sliding pads within each gap between adjacent bearing section are spaced apart in the axial direction and arranged along the circumference of said sections, wherein each of said tubular bearing sections has a substantially uniform wall thickness along the complete circumference thereof, wherein a cross-section of said tubular bearing sections is also mirror-symmetric relative to a vertical axis, wherein a first smaller substantially semi-circular cross-sectional area m.sub.1 of each bearing section is is arranged above a neutral axis Y and at a suitable distance apart from said neutral axis Y, while in the area below said neutral axis Y a larger substantially semi-circular area m.sub.2 with a larger radius R.sub.2 is arranged, wherein terminal points C, C′ of the larger substantially semi-circular area are arranged below the neutral axis Y and at a suitable distance apart from it, wherein the larger substantially semi-circular area is symmetric relative to the vertical axis Z and straight sections n.sub.2, n.sub.2′ extend tangentially across said neutral axis Y at a pre-determined distance from said neutral axis Y, wherein straight sections n.sub.1, n.sub.1′ extending toward terminal points A, A′ form an obtuse angle with said smaller substantially semi-circular area.

2. The bearing assembly according to claim 1, wherein said straight sections n.sub.2, n.sub.2′, which extend tangentially with respect to said larger substantially semi-circular area m.sub.2 with larger radius R.sub.2 protrude above said neutral axis Y, are arranged parallel with each other.

3. The bearing assembly according to claim 1, wherein said straight sections n.sub.2, n.sub.2′, which extend tangentially with regard to said larger substantially semi-circular area m.sub.2 with larger radius R.sub.2 protrude above said neutral axis Y, and are inclined relative to each other and symmetrically converge towards the said smaller substantially semi-circular area m.sub.1 with smaller radius R.sub.1 relative to vertical axis Y.

4. The bearing assembly according to claim 3, wherein the radius R.sub.1 of said smaller substantially semi-circular area m.sub.1 within the tension zone above the neutral axis Y and the radius R.sub.2 of the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral zone Y fulfil the following condition:
1/4≤(R.sub.1/R.sub.2)≤3/4.

5. The bearing assembly according to claim 4, wherein a height h of each tubular bearing section defined by the distance between vertex points E, F of said substantially semi-circular areas m.sub.1, m.sub.2, relative to the width b of the tubular bearing section which corresponds to diameter of the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y, fulfil the condition:
1/2≤(b/h)≤4/5, wherein the preferred ratio between the width b and the height h is approximately 3:4.

6. The bearing assembly according to claim 5, c wherein length d, which represents the distance between the neutral axis Y and each intersection B, B′ between each tangentially from the smaller substantially semi-circular area m.sub.1 within the tension zone above the neutral axis Y and straight sections n.sub.1, n.sub.1′extending tangentially from the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis l and straight sections n.sub.2, n.sub.2′ extending towards the smaller substantially semi-circular area m.sub.1 is defined with regard to the total height h of said tubular bearing section such that the following condition is fulfilled:
h/5≤d≤h/4.

7. The bearing assembly according to claim 6, wherein the angle is selected within the range:
140°≤γ≤170°.

8. The bearing assembly according to claim 7, wherein an angle β between the normal line of each tangentially from the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis and straight sections n.sub.2, n.sub.2′ and extending along the neutral axis Y is selected within the range:
0<β25°.

9. The bearing assembly according to claim 8, wherein a wall thickness t of each tubular bearing section relative to the width b thereof is selected within the range:
3 mm≤t≤(b/20).

10. The bearing assembly according to claim 9, wherein length L.sub.9 of the mutually overlapping area, in which each internal tubular bearing section having the length L.sub.1 and consisting of steel is fully extended from each external tubular bearing section having the length L.sub.0 and consisting of steel in the axial direction, with regard to the height h of said internal tubular bearing section fulfils the following condition:
1.5 h≤L.sub.9≤3 h.

11. The bearing assembly according to claim 10, wherein each of said tubular bearing sections in the telescopic bearing assembly consists of a cold formed steel plate shaped as a continuous shell and is welded in the area of the vertex point F on the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y.

12. The bearing assembly according to claim 10, wherein each of said tubular bearing sections in the telescopic bearing assembly consists of a cold formed steel plate shaped as continuous shell and is welded in the areas C, C′ of transition from the larger substantially semi-circular area m.sub.2 into each associated tangential straight sections n.sub.2, n.sub.2′ within the compression zone below the neutral axis Y.

13. The bearing assembly according to claim 12, wherein each of said substantially semi-circular areas m.sub.1, m.sub.2 above and below the neutral axis Y is formed by bending a metallic sheet having a pre-determined thickness t, and is approximated by a regular equilateral polygon having at least 16 sides.

14. The bearing assembly according to claim 13, wherein each of said substantially semi-circular areas m.sub.1, m.sub.2 above and below the neutral axis Y is formed by bending a metallic sheet having a pre-determined thickness t, and is approximated by a regular equilateral polygon having at least 24 sides.

15. A mobile telescopic hydraulic crane, comprising: a bearing platform adapted for mounting of said crane on a motor vehicle and is furnished with at least a pair of telescopic supporting legs suitable for supporting said crane on the ground during transporting of a load in order to ensure its carrying capacity and stability, a column having a first area within a first terminal portion and a second area within a second terminal portion attached pivotally around a vertical geometric axis to a primary bearing arm of the crane, which is supported and pivoted around said horizontal geometrical axis by a hydraulic cylinder; telescoping secondary bearing arm, which is pivotally attached by its first end portion to the second terminal portion of said primary arm and which is equipped with an attachment point suitable for mounting a grabber or other suitable assembly for manipulating a load, wherein said telescopic secondary arm is supported and pivoted around said horizontal geometric axis by means of a hydraulic cylinder on said primary arm, which is directly or indirectly pivotally connected to said primary arm and to said secondary arm via a suitable linking mechanism, wherein said secondary arm comprises an extendable bearing assembly that is extendable in the longitudinal direction X.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present disclosure will be further explained by embodiments and in connection with attached drawings, wherein:

[0023] FIG. 1 presents a mobile hydraulic crane, which is suitable for mounting on a motor vehicle (not shown) and comprises a telescopic arm with a bearing assembly according to the present disclosure;

[0024] FIG. 2 shows a schematic view of a telescopic bearing assembly consisting of two tubular bearing sections according to the present disclosure, which are inserted within each other;

[0025] FIG. 3 shows the first embodiment of one of the tubular bearing sections, a cross-section along the plane II-II according to FIG. 2; and

[0026] FIG. 4 shows the second embodiment of one of the tubular bearing sections, a cross-section along the plane II-II according to FIG. 2.

DETAILED DESCRIPTION

[0027] A bearing assembly 40 in a mobile hydraulic crane telescopic arm 4 according to FIG. 1 and FIG. 2 and comprises at least two tubular bearing sections 44, 45, which are inserted within each other and are in a controlled manner telescopically moveable along each other in the axial direction thereof by a suitable driving means. In the example shown and for simplification, only one external tubular bearing section 44 having a pre-determined length L.sub.0 and one inner tubular bearing section 45 having a pre-determined length L.sub.1 are shown, wherein due to their similarity and complementary shape of their transversal cross-sections, insertion of the internal tubular bearing section 45 into the external bearing section 44 is enabled by simultaneously assuring a minimal overlapping length L.sub.9 and approximately uniform spacing between said sections 44, 45 along the complete circumference thereof. Suitable sliding pads 46′, 46″ are inserted within each gap between adjacent bearing sections 44, 45, which are correspondingly spaced apart from each other in the axial direction of the arm 4 and are also properly arranged along the circumference of said sections 44, 45 in order to enable suitable matching between said mutually abutting bearing sections 44, 45 by simultaneously allowing required movements relative to each other in the axial direction X in order to maintain friction as low as possible. Each of said tubular bearing sections 44, 45, when observed in its cross-section, is designed with a substantially uniform wall thickness t along the complete circumference thereof, while at the same time said cross-section is also mirror-symmetric with regard to the vertical geometric axis Z, in the direction of which the load F.sub.Q weight force extends when assembly 40 of the crane is exposed to static loads and stresses resulting from a bending moment around the horizontal geometrical axis Y as a neutral axis of each effective bearing cross-section of each bearing section 45, below which a compression zone is located, while a tension zone is located above said neutral geometrical axis Y.

[0028] The telescopic assembly 40 has bearing sections 44, 45 such that a smaller substantially semi-circular area m.sub.1 with a smaller radius R.sub.1 is arranged in the area of said tension zone above and at a suitable distance from said neutral axis Y, while in the area within the compression zone below said neutral axis Y a larger substantially semi-circular area m.sub.2 with a larger radius R.sub.2 is arranged, which ends in its terminal points C, C′ below and at a suitable distance from the neutral axis Y, and is on both sides symmetric relative to the vertical axis Z tangentially extended by straight sections n.sub.2, n.sub.2′, which extend across said neutral axis Y, such that each of them coincides with a complementary straight section n.sub.1, n.sub.1′ at a pre-determined distance d apart from said neutral axis Y and at an obtuse angle γ and symmetric relative to the vertical axis Z, by which said substantially semi-circular area m.sub.1 with a smaller radius R.sub.1 extends in each of its terminal points A, A′.

[0029] According to one of the embodiments of each of the tubular bearing sections 44, 45 of the bearing assembly 40 according to the present disclosure (FIG. 3), the straight sections n.sub.2, n.sub.2′, which extend tangentially with respect to said larger substantially semi-circular area m.sub.2 with a larger radius R.sub.2 and protrude above said neutral axis Y, are arranged parallel to each other.

[0030] According to a further embodiment of the tubular bearing sections 44, 45 of the bearing assembly 40 according to the present disclosure (FIG. 4), the straight sections n.sub.2, n.sub.2′, which extend tangentially with regard to said larger substantially semi-circular area m.sub.2 with a larger radius R.sub.2 and protrude above said neutral axis Y, are inclined relative to each other and converge towards the said smaller substantially semi-circular area m.sub.1 with a smaller radius R.sub.1 symmetrically relative to said vertical axis Z.

[0031] The radius R.sub.1 of the smaller substantially semi-circular area m.sub.1 within the tension zone above the neutral axis Y and the radius R.sub.2 of the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral zone Y are determined in such a manner that the condition 1/4≤(R.sub.1/R.sub.2)≤3/4 is fulfilled.

[0032] The height h of each tubular bearing section 44, 45, namely the distance between the vertex points E, F (FIGS. 3 and 4) of said substantially semi-circular areas m.sub.1, m.sub.2, relative to the width b of the tubular bearing section 44, 45, which corresponds to diameter of the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y, is determined in such manner that the condition 1/2≤(b/h)≤4/5 is fulfilled, however the preferred ratio between the width b and the height h is approximately 3:4.

[0033] The length d, which represents the distance between the neutral axis Y and each intersection B, B′ between the smaller substantially semi-circular area m.sub.1 within the tension zone above the neutral axis Y extending straight section n.sub.1, n.sub.1′ and the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y extending straight section n.sub.2, n.sub.2′ in the direction towards the smaller substantially semi-circular area m.sub.1 is relative to the total height h of said tubular bearing section 44, 45 determined in such a manner that the condition h/5≤d≤h/4 is fulfilled.

[0034] The angle γ between the smaller substantially semi-circular area m.sub.1 within the tension zone above the neutral axis Y extending straight section n.sub.1, n.sub.1′ and the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y extending straight section n.sub.2, n.sub.2′ is selected within the range of 140°≤γ≤170°.

[0035] In cases where the straight sections n.sub.2, n.sub.2′ are not parallel to each other (FIG. 4), the angle) β between the normal line of the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y extending straight section n.sub.2, n.sub.2′ and the neutral bending axis Y is selected within the range 0<β≤25°. In the case where the straight sections n.sub.2, n.sub.2′ are parallel to each other (FIG. 3), the condition β=0 is fulfilled.

[0036] It is understood by a person skilled in the art that each tubular bearing section 44, 45 is in the area above the neutral axis equipped with an additional longitudinal crease, which is consists of two straight sections n.sub.1, n.sub.2; n.sub.1′, n.sub.2, which converge at an obtuse angle γ and each individually belong to the larger substantially semi-circular areas m.sub.1, m.sub.2.

[0037] Such a concept of creating such a cross-section results in substantial reinforcement of each tubular bearing section 44, 45 from the perspective of strength and deformations and at the same time also leads to a substantially more effective fitment between sections 44, 45 even in the case of the smallest length L.sub.9 of mutual overlapping.

[0038] Consequently, the wall thickness t of each tubular bearing section 44, 45 can be selected within the range 3 mm≤t≤(b/20). Furthermore, the length L.sub.9 of the mutually overlapping area of the sections 44, 45 in the case that internal tubular bearing section 45, having the length L.sub.1 and consisting of steel is fully extended in the axial direction from each external tubular bearing section 44 having length L.sub.0 and consisting of steel fulfils the condition 1.5 h≤L.sub.9≤3 h where h is the height of said internal tubular bearing.

[0039] In one embodiment of the present disclosure, each of said tubular bearing sections 44, 45 in the telescopic bearing assembly 40 consists of a cold formed steel plate and is shaped as a continuous shell and welded in the area of the vertex point F on the larger substantially semi-circular area m.sub.2 within the compression zone below the neutral axis Y. In an alternative embodiment of the present disclosure each of said tubular bearing sections 44, 45 in the telescopic bearing assembly 40 consists of a cold formed steel plate shaped as continuous shell and is welded in the transition areas C, C′ from the larger substantially semi-circular area m.sub.2 into associated tangential straight sections n.sub.2, n.sub.2′ within the compression zone below the neutral axis Y.

[0040] However, if manufacturing of perfectly or approximately rounded areas m.sub.1, m.sub.2 is too complicated using the required technical equipment each of said substantially semi-circular areas m.sub.1, m.sub.2 above and below the neutral axis Y could be approximated by bending of a metallic sheet having a pre-determined thickness t and approximating a regular equilateral polygon, which has at least 16 sides, preferably having at least 24 sides. Even in this case, by approximating a circular arc with an inscribed or circumscribed polygon with a sufficiently large number of vertices provides sufficiently similar rounded areas mm.sub.1, m.sub.2, which may provide the same advantages with regard to deformations and fitment between sections 44, 45.

[0041] The scope of the present disclosure also includes a mobile telescopic hydraulic crane with a bearing platform 1, which is adapted for mounting of said crane on each motor vehicle and is optionally furnished with at least a pair of telescopic supporting legs 11, which are suitable for supporting said crane on the ground during transporting of a load in order to ensure carrying capacity and stability. A first terminal portion 23 of platform 1 is pivotally attached to column 2 around the vertical geometric axis, furthermore, a first terminal portion 31 of a primary bearing arm 3 of the crane is pivotally attached around the horizontal geometric axis to the second terminal portion 22 of said column 2 and is supported and pivoted around said horizontal geometrical axis on said column 2 by means of a hydraulic cylinder 21, which is pivotally connected on one side with said column 2 and on the other side with said primary bearing arm 3. A telescoping secondary bearing arm 4 of the crane is attached by its first end portion 41 pivotally around the horizontal geometric axis to the second terminal portion 32 of said primary arm 3 and is on its second free terminal portion 42 equipped with an attachment point 5, which is suitable for mounting a grabber 6 or any other suitable assembly for manipulating a load. Said telescopic secondary arm 4 is supported and pivoted around said horizontal geometric axis on said primary arm 3 by means of a hydraulic cylinder 34, which is directly or indirectly connected to said primary arm 3 and said secondary arm 4 by a suitable linking mechanism.

[0042] The secondary arm 4 may comprises an extendable bearing section 40 which extends in the longitudinal direction X according to any of the previously described features.