Abstract
A crane includes a crane pillar rotatably mounted about a vertical axis, at least one jib, connected to the crane pillar and pivotally mounted about a horizontal axis, at least one jib extension movably mounted in the jib, and at least one piston-cylinder unit for extending and retracting the jib extension relative to the jib. The first end of the piston-cylinder unit engages the jib via at least one first force-introducing region, and the second end engages the at least one jib extension via at least one second force-introducing region. The piston-cylinder unit has a central plane parallel to the horizontal axis about which the jib is pivotally mounted, and the piston-cylinder unit has a compressive deformation perpendicular to the central plane in a pressure-loaded state while the jib is being extended and a tensile deformation opposite the compressive deformation in a tension-loaded state while the jib is being retracted.
Claims
1. A crane comprising a crane pillar mounted rotatably about a vertical axis, at least one jib connected to the crane pillar and mounted pivotably about a horizontal axis and at least one jib extension mounted displaceably in the jib, and at least one piston-cylinder unit for extending and retracting the jib extension relative to the jib, wherein the at least one piston-cylinder unit with a first end engages the jib by way of at least one first force-application region, and with a second end engages the at least one jib extension by way of at least two second force-application regions, wherein the at least one piston-cylinder unit has a central plane which extends in a viewing direction parallel to the horizontal axis about which the jib is pivotably mounted, and wherein the at least one piston-cylinder unit in a compressive-loaded condition upon extension has a compressive deformation in a direction perpendicularly to the central plane and in a tensile-loaded condition upon retraction has a tensile deformation in a direction opposite to the compressive deformation, and wherein one of said at least two second force-application regions is arranged in displaced relationship with the central plane of the at least one piston-cylinder unit in the direction opposite to the compressive deformation, and the other of said at least two second force-application regions is arranged in displaced relationship with the central plane in the direction opposite to the tensile deformation.
2. A crane as set forth in claim 1 wherein the second end of the at least one piston-cylinder unit engages the at least one jib extension by way of at least four second force-application regions, wherein two of the at least four second force-application regions are arranged in displaced relationship with the central plane in the direction opposite to the compressive deformation, and two of the at least four second force-application regions are arranged in displaced relationship with the central plane in the direction opposite to the tensile deformation.
3. A crane as set forth in claim 2, wherein the at least four second force-application regions are arranged preferably symmetrically on both sides of the at least one piston-cylinder unit.
4. A crane as set forth in claim 1, wherein at least one of the two second force-application regions, by way of which the second end of the at least one piston-cylinder unit engages the at least one jib extension, comprises at least one insert segment.
5. A crane as set forth in claim 4, wherein the at least one insert segment is mounted at least region-wise in positively locking relationship in a bore of the at least one piston-cylinder unit.
6. A crane as set forth in claim 5, wherein the at least one insert segment is mounted in the bore rotatably about an axis of rotation extending parallel to the horizontal axis about which the jib is pivotably mounted.
7. A crane as set forth in claim 4, wherein the at least one insert segment has at least one straight surface.
8. A crane as set forth in claim 7, wherein the at least one insert segment bears with the at least one straight surface against at least one pivot mounting bar, wherein the at least one pivot mounting bar is connected to the at least one jib extension by way of a fixing device.
9. A crane as set forth in claim 8, wherein the at least one pivot mounting bar is mounted in an opening of the at least one piston-cylinder unit.
10. A crane as set forth in claim 8, wherein the at least one pivot mounting bar is mounted in positively locking relationship with play in an opening of the at least one piston-cylinder unit.
11. A crane as set forth in claim 1, wherein at least one of the force-application regions, by way of which the second end of the at least one piston-cylinder unit engages the at least one jib extension, is embodied by at least one bolt device.
12. A crane as set forth in claim 11, wherein the at least one bolt device is mounted at least region-wise in positively locking relationship in a bore of the at least one piston-cylinder unit.
13. A crane as set forth in claim 11, wherein the at least one bolt device is connected by way of an intermediate device to at least one pivot mounting bar, wherein the at least one pivot mounting bar is connected to the at least one jib extension by way of a fixing device.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Details and advantageous embodiments of the invention which are recited in the appendant claims are described in greater detail in the specific description hereinafter by means of the Figures which have not yet been described in the introductory part of the description. In the drawings:
(2) FIG. 1 is a diagrammatic perspective view of a conventional crane;
(3) FIGS. 2a and 2b illustrate how conventional transmission force is effected when extending or retracting a jib extension relative to a jib;
(4) FIG. 3a is a diagram illustrating flexural movements or stresses in state-of-the-art piston rods;
(5) FIGS. 3b diagrammatically shows the flexural moment or stress configuration in a piston rod in the case of a force-application region arranged in displaced relationship with the central plane,
(6) FIGS. 4a and 4b show a diagrammatic perspective view (FIG. 4a) and a diagrammatic side view (FIG. 4b) of a portion of a crane, that is relevant for understanding a first embodiment of the invention,
(7) FIG. 4c shows a diagrammatic view from above on to two partial regions of the rod head in the first embodiment,
(8) FIGS. 5a and 5b show a diagrammatic perspective view (FIG. 5a) and a diagrammatic side view (FIG. 5b) of a portion of a crane, that is relevant for understanding a second embodiment of the invention,
(9) FIG. 5c shows a diagrammatic view from above on to two partial regions of the rod head in the second embodiment,
(10) FIG. 5d shows a diagrammatic cross-section of the rod head in the second embodiment, and
(11) FIGS. 6a and 6b show a diagrammatic perspective view (FIG. 6a) and a diagrammatic side view (FIG. 6b) of portions of a crane, that are relevant for understanding a third embodiment of the invention.
(12) As already stated hereinbefore the basic idea of the invention is that at least some of the force-application regions, by way of which the at least one piston-cylinder unit with its second end engages the at least one jib extension, are arranged in displaced relationship with the central plane of the piston-cylinder unit. By virtue of such eccentric application of forces in relation to the central plane of the piston-cylinder unit the force for extension and retraction of the jib extension in the deformed condition can be increased markedly in comparison with a central application of forces in relation to the central plane without the piston-cylinder unit having to be reinforced for that purpose.
(13) That effect can be seen from FIG. 3b: this Figure diagrammatically shows, like also above-described FIGS. 3a, the flexural moment or stress configuration in the piston rod, wherein sub-FIG. (1) of FIG. 3b again shows the flexural moment or stress configuration resulting from the (pure) ambient deformation f, sub-FIG. (2) shows the flexural moment or stress configuration resulting from an eccentrically applied extension force F.sub.A, wherein reference e denotes the eccentricity of the application of force, and sub-FIG. (3) shows the overall configuration resulting from superimpositioning of the components shown in sub-FIGS. (1) and (2). If now the two sub-FIGS. (3) of FIGS. 3a and 3b are compared it is directly apparent that the maximum amplitude in the case of FIG. 3b is markedly reduced in comparison with FIG. 3a. That means that the load moved by means of the piston-cylinder unit or the jib and the jib extension, with the deformation of the piston-cylinder unit remaining the same, can be markedly increased.
(14) FIGS. 4a, 4b and 4c show a first embodiment of the invention, wherein only the region of a loading crane, that is relevant to understanding the invention, is to be seen here in each case. In this first embodiment the piston-cylinder unit 6 with its first end, in this case being the end which includes the cylinder 18, engages the jib 4 by way of a first force-application region 7, while with its second end which in this case is the rod head 20 of the piston rod 19 it engages the jib extension 5 by way of four further force-application regions 8. Those four force-application regions 8 of which only two are visible in each of the Figures by virtue of the views adopted are in this embodiment respectively embodied by substantially cylindrical insert segments 26 and 26, wherein those insert segments 26 and 26 are mounted in positively locking relationship in a respective bore 30 in the rod head 20 of the piston rod 19 of the piston-cylinder unit 6, more specifically in such a way that they are mounted in the bores 30 rotatably about an axis of rotation R extending parallel to the horizontal axis H about which the jib 4 is mounted pivotably. The insert segments 26 and 26 each have on one side a respective straight surface 31, by way of which they bear against the pivot mounting bars 22, wherein those two pivot mounting bars 22 are connected to the jib extension 5 by way of a fixing device 21. The two pivot mounting bars 22 are mounted in positively locking relationship with play in two openings 29 arranged at both sides symmetrically on the rod head 20. This means that the openings 29 are somewhat larger than the pivot mounting bars 22. By virtue of that positively locking relationship with play and the fact that the insert segments 26 and 26 which are connected to the pivot mounting bars 22 are mounted rotatably, overall the pivot mounting bars 22 are rotatable in the openings 29 in a limited angular range a about an axis of rotation extending parallel to the horizontal axis H about which the jib 4 is mounted pivotably. In the event of an excessively great angular deviation between the piston rod 19 and the jib extension 5 or the pivot mounting bars 22 the positively locking relationship becomes operative and the connection is so-to-speak clamped and in that way buckling of the piston rod 19 is avoided. The pivot mounting bars 22 are prevented from moving away upwardly (as seen in FIG. 4b) or downwardly by a lock member 24 fixed to the rod head 20 by means of two screws 25 on the one hand and a specific configuration in the regions 27 of the pivot mounting bars 22 on the other hand. As regards the precise arrangement of the four force-application regions 8 in this embodiment, it is to be emphasised that two of those four force-application regions 8 are arranged on the side of the rod head 20 that is visible in FIG. 4b and the other two force-application regions 8 are arranged symmetrically on the opposite side of the rod head 20. In addition, a respective one of the two force-application regions 8 present on the two sides is arranged in displaced relationship with the central plane M of the piston-cylinder 6 above same while the other of the two force-application regions 8 is arranged in displaced relationship with the central plane M below same. In other words therefore one of the two force-application regions 8 is arranged in displaced relationship with the central plane M in the direction opposite to the compressive deformation D and the other of the two force-application regions 8 is arranged in displaced relationship with the central plane M in the direction opposite to the tensile deformation Z, wherein the compressive deformation D in a compressive-loaded condition occurs upon extension of the jib extension 5 (see also FIG. 3b) and the tensile deformation in a tensile-loaded condition occurs upon retraction of the jib extension 5. This means that the force-application region 26 arranged in displaced relationship with the central plane M above it at a spacing A deploys a load-relief action in the compressive-loaded condition and the force-application region 26 arranged in displaced relationship with the central plane M below same at a spacing A deploys a load-relief action in the tensile-loaded condition.
(15) It should also be noted that FIG. 4c involves a divided view of the rod head 20 from above, wherein the left-hand part of the view shows the lock member 24 which prevents the pivot mounting bars 22 from moving upwardlythat is to say towards the viewerwhile the right-hand part of the view shows a cross-section in the region of the insert segments 26.
(16) FIGS. 5a, 5b, 5c and 5d show a second preferred embodiment of the invention, the same views being adopted in FIGS. 5a, 5b and 5c as in FIGS. 4a, 4b and 4c. The transmission of force between the rod head 20 of the piston rod 19 of the piston-cylinder unit 6 to the jib extension 5 is implemented by way of the force-application regions 8 in the same way as in the first embodiment described above. Only the kind of fixing of the pivot mounting bars 22 to the piston rod head 20 is different in this embodiment. As already stated the pivot mounting bars 22 are prevented from moving upwardly in the first embodiment by the lock member screwed to the rod head 20. In the second embodiment, in comparison therewith, that effect is achieved by means of the pivot mounting bars 22 being screwed to the rod head 20. That screw means can be seen in particular in FIG. 5d: reference 28 denotes a screw, reference 32 denotes two washers and reference 30 denotes a nut having a female thread corresponding to the screw 28.
(17) FIGS. 6a and 6b show a third preferred embodiment of the invention, wherein a respective portion of a crane that is relevant to understanding of this embodiment is to be seen therein. In that respect FIG. 6a is a diagrammatic perspective view and FIG. 6b is a diagrammatic side view. In this third embodiment the force-application regions 8, by way of which the piston-cylinder unit 6 engages the jib extension 5, are embodied by two cylindrical bolt devices 35 and 35 mounted in positively locking relationship in bores in the rod head 20 of the piston-cylinder unit 6. The ends of the bolt devices 35 and 35 project at both sides out of the rod head 20 and are mounted in slots 33 and 33 of two intermediate devices 36 in the form of substantially rectangular plates. The two intermediate devices 36 arranged at both sides on the rod head 20 are in turn mounted in openings 34 in two pivot mounting bars 22, wherein the openings 34 (to be seen in FIG. 6b) are enlarged upwardly and downwardly in such a way that the intermediate devices 36 are displaceable in respect of height relative to the pivot mounting bars. The two pivot mounting bars 22 are again (as also in the other two embodiments) connected to the jib extension 5 by way of a fixing device 21. In this third embodiment the bolt device 33 is arranged in displaced relationship with the central plane M below same at a spacing A and deploys a load-relief action in the tensile-loaded condition. The second bolt device 33 is arranged in displaced relationship with the central plane M above same at a spacing A and deploys a load-relief action in the compressive-loaded condition.
