Abstract
A vehicle crane comprising a jib that is raised and lowered by at least one main tensile connector, and a counter jib, where the main tensile connector extends between a first connecting point in the region of a jib head and a second connecting point in the region of a counter jib head. To reduce loading on the jib, in particular during raising and lowering and increase its bearing load overall, the jib has a third connecting point between the first connecting point and its foot opposite the head, and a secondary tensile connector extends between the third connecting point and a fourth connecting point in the region of the head of the counter jib, or the secondary tensile connector extends between the third connecting point via a seventh connecting point on the main tensile connector and a fourth connecting point in the region of the main jib foot.
Claims
1. A vehicle crane, said vehicle crane comprising: a jib that can be raised and lowered by at least one main tensile connector, and a counter jib, wherein the main tensile connector extends between a first connecting point in the region of a jib head of the jib and a second connecting point in the region of a counter jib head of the counter jib; wherein the jib has a third connecting point located between the first connecting point and a jib foot opposite the jib head, and wherein a secondary tensile connector extends between the third connecting point via a seventh connecting point on the main tensile connector and an eighth connecting point at the jib in the region of the jib foot.
2. The vehicle crane as claimed in claim 1, wherein the main tensile connector is variable in length.
3. The vehicle crane as claimed in claim 2, wherein the main tensile connector includes sections and is variable in length in the sections.
4. The vehicle crane as claimed in claim 1, wherein the secondary tensile connector is variable in length.
5. The vehicle crane as claimed in claim 4, wherein the secondary tensile connector includes sections and is variable in length in the sections.
6. The vehicle crane as claimed in claim 1, wherein the jib extends without joints between the jib foot and the jib head.
7. The vehicle crane as claimed in claim 1, wherein the jib has a plurality of girders or an individual girder extending between the jib foot and the jib head comprising lattice girders and/or box girders.
8. The vehicle crane as claimed in claim 1, wherein said vehicle crane has a superstructure that is arranged so as to be rotatable on a lower carriage and on which the jib is supported in a luffable manner via the jib foot.
9. The vehicle crane as claimed in claim 8, wherein the counter jib is supported on the superstructure.
10. The vehicle crane as claimed in claim 8, wherein one or both of the superstructure or the counter jib foot of the counter jib has a winch drive, and wherein the main tensile connector and the secondary tensile connector are each operatively connected to a said winch drive.
11. The vehicle crane as claimed in claim 1, wherein the jib has a fifth connecting point to which an auxiliary means is coupled, and wherein the auxiliary means is connected to the main tensile connector at a sixth connecting point.
12. The vehicle crane as claimed in claim 11, wherein the fifth connecting point is located between the foot of the jib and the third connecting point on the jib.
13. The vehicle crane as claimed in claim 1, wherein the region for the third connecting point, as seen in the longitudinal direction of the jib, is between 25% and 75% of the length of the jib.
14. The vehicle crane as claimed in claim 13, wherein the region for the third connecting point, as seen in the longitudinal direction of the jib, is between 40% and 60% of the length of the jib.
15. The vehicle crane as claimed in claim 1, wherein a counterweight is suspended from the counter jib.
16. The vehicle crane as claimed in claim 1, wherein the counter jib comprises a superlift jib and/or an A-block.
17. A method for reducing the loading on a jib of a vehicle crane, wherein the vehicle crane comprises the jib which can be raised and lowered by at least one main tensile connector, and a counter jib, wherein the main tensile connector extends between a first connecting point in the region of a jib head of the jib and a second connecting point in the region of a counter jib head of the counter jib, and wherein the jib has a third connecting point located between the first connecting point and a jib foot opposite the jib head with the jib being supported in a luffable manner via the jib foot, and wherein a secondary tensile connector extends between the third connecting point via a seventh connecting point on the main tensile connector and an eighth connecting point at the jib in the region of the jib foot, said method comprising: loading the jib during operation and/or during raising and lowering; and transmitting a compensating force to the jib at the third connecting point by the secondary tensile connector coupled to the third connecting point.
18. The method as claimed in claim 17, wherein said transmitting a compensating force to the jib further comprises controlling the compensating force.
19. The method as claimed in claim 18, wherein the compensation force to be transmitted is controlled in at least one of the following ways: force-controlled, path-controlled, continuously, constantly, linearly, stepwise.
20. The method of claim 18, wherein at least one of the following features of the vehicle crane is taken into consideration in said controlling the compensation force: bearing load points, loaded radius, counterweight radius, bearing load curve.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 shows a side view of a vehicle crane with its jib in an initial position;
(2) FIG. 2 shows the vehicle crane of FIG. 1 with its jib in a position raised with respect to the initial position, in an otherwise unchanged view;
(3) FIG. 3 shows the vehicle crane of FIG. 1 and FIG. 2 during the loading operation, in an otherwise identical view;
(4) FIG. 4 shows the vehicle crane of FIG. 1 in a first alternative embodiment, in an otherwise identical view;
(5) FIG. 5 shows the vehicle crane of FIG. 1 in a second alternative embodiment, in an otherwise identical view;
(6) FIG. 6 shows the vehicle crane of FIG. 1 in a third alternative embodiment, in an otherwise identical view;
(7) FIG. 7 shows the vehicle crane of FIG. 2 in a fourth alternative embodiment, in an otherwise identical view.
DESCRIPTION OF THE PREFERRED EMBODIMENT
(8) FIG. 1 shows a vehicle crane 1 in accordance with the invention which is standing on ground U and comprises a long jib 2 extending in its longitudinal direction X. It can be seen that the jib 2 shown here by way of example is designed as an intrinsically jointless truss girder or lattice mast girder which, because it has no telescoping capability, has a length which is fixed in this respect. The jib 2 can be composed of one individual girder or of a plurality of girders connected to another in a bending-resistant manner. Furthermore, the vehicle crane 1 has a lower carriage 3 which has a crawler track 4 in the example shown here. Arranged on the lower carriage 3 is a superstructure 5 which carries the jib 2 and which can be rotated relative to the lower carriage 3 about a vertical axis Z. The jib 2 which extends in its longitudinal direction X is supported on the superstructure 5 by means of its foot 2a and is articulated in a luffable manner via a horizontal luffing axis Y in a vertical plane in order to raise, lower or luff the jib 2 during operation. Arranged in the region of a head 2b opposite the foot 2a of the jib 2 is a first connecting point 7a which is coupled to a main tensile connector or means 7. Depending upon the configuration, such a coupling can be a fastening, deflection or a combination thereof. The main tensile connector 7 is coupled oppositely to a head 6b of a counter jib 6 in a second connecting point 7b. This counter jib 6 is also referred to as a superlift jib or derrick mast. In this case, depending upon the configuration it is also possible for such a coupling to be a fastening, deflection or a combination. The counter jib 6 is typically also designed as a lattice mast girder and is luffably mounted on the superstructure 5. A further third connecting point 8a is arranged in a region of the jib 2 located between the first connecting point 7a and the foot 2a and is coupled, i.e. fastened and/or deflected, with a secondary tensile connector or means 8. The region for the third connecting point 8a is between 25% and 75%, preferably between 40% and 60%, of the length of the jib 2, as seen in the longitudinal direction X of the jib 2. Oppositely, the secondary tensile connector 8 is coupled, i.e. fastened and/or deflected, on the head 6b of the counter jib 6 in a fourth connecting point 8b. Therefore, the main tensile connector 7 and also the secondary tensile connector 8 each extend between the jib 2 and the counter jib 6. The counter jib 6 is connected via a rearward guying arrangement 9 to the superstructure 6 or a typical further counter jib 6′ which is articulated at this location and is referred to as an A-block or support block. In the case of the types of set-up comprising a counter jib 6 and counter jib 6′, the secondary tensile connector 8 is attached only to the head 6a of the counter jib 6. At its end opposite the jib 2, the superstructure 5 supports a counterweight 10. Also, an additional counterweight 12 which is also referred to as a superlift is suspended from the head 6b of the counter jib 6 via a suspension 13. As understood herein and in the art, the main tensile connector 7 and secondary tensile connector 8 may be cables, such as single cables or multiple cables running in parallel, cables used with pulley blocks, as described below, for tensioning the connector and/or adapting its length, or may be single or multiple rods or combinations thereof, or may be chains or belts.
(9) In order to raise, luff during operation and lower the jib 2 at a later stage, the main tensile connector 7 and the secondary tensile connector 8 are variable in length in relation to the portion between the head 2b of the jib 2 and the head 6b of the counter jib 6. Pulley-block like reeving arrangements are typically provided for this purpose. In a corresponding manner, the main tensile connector 7 and the secondary tensile connector 8 are thus each fastened and deflected in their second and fourth connecting point 7b, 8b respectively. For the purpose of raising, luffing and lowering, the counter jib 6 is fixed in its operating position at a preselected angle on the superstructure 5 via the guying arrangement 9 and a support. The length of the main tensile connector 7 and the secondary tensile connector 8 is changed via winches 14 which are arranged on the superstructure 5 or on the foot 6a of the counter jib 6. The jib 2 which extends in its substantially horizontal initial position S1 can be vertically raised, luffed and then lowered by means of a corresponding change in the length of the main tensile connector 7. In parallel therewith, a tensile force in the form of a compensation force K is transmitted to the jib 2 by the secondary tensile connector 8 in order to reduce or compensate for the loading, in particular bending moments, which are produced from the empty weight of the jib 2 which is otherwise unsupported between the first connecting point 7a and its foot 2a. The control required for this purpose can be effected in many ways, including e.g. force-controlled or path-controlled, continuous, constant, linear or else stepwise. In this case, the control can take into consideration further features, such as e.g. the individual bearing load points and/or bearing load curves of the vehicle crane together with the respectively adopted rotation of its superstructure 5 relative to the lower carriage 3.
(10) This tensile force is applied to the secondary tensile connector 8 preferably via a fastening winch. For this purpose, the fastening winch is driven electrically or hydraulically. It is also feasible for hydraulic tensioning cylinders to be used for this purpose which act upon the secondary tensile connector 8 directly, via cable drives or in a clamping manner.
(11) In accordance with an aspect of the present invention and the exemplified embodiments, the lower end of the jib 2 having a length corresponding to 10% of the length of the entire jib 2 is understood as being in the region of the foot 2a of the jib 2. In the case of a jib 2 designed as a lattice mast, the lower end of the jib 2 thus comprises at least the so-called foot piece, with which the jib 2 is articulated to the superstructure 5, and the so-called first intermediate piece which adjoins thereto and which is then adjoined by the sequence of the lattice mast pieces of the jib 2. Even if, in the case of a short jib 2, the foot piece and the first intermediate piece exceed the defined 10% of the length of the entire jib 2, they form in any case the region of the foot 2a of the jib 2.
(12) FIG. 2 shows one of the raised positions S2 of the vehicle crane 1, of which the jib 2 has been raised in the previously described manner via the main tensile connector 7 and the secondary tensile connector 8. By reason of the relative length of the jib 2 which changes in this case in parallel with the ground U, the changing bending moments have been taken into consideration by the control, whereupon a corresponding adaptation of the compensation force K was effected via the secondary tensile connector 8 in a manner which cannot be seen more closely.
(13) FIG. 3 illustrates an operating position S3 of the vehicle crane 1, in which its jib 2 has been raised to a relatively steep position in order to convey a picked-up load L. In the operating position S3, the jib 2 has a considerably shorter unsupported length, in particular in comparison with the initial position S1, wherein the compensation force K which can be transmitted via the secondary tensile connector 8 is now used primarily to increase its bearing load.
(14) FIG. 4 shows the vehicle crane 1 once again in its initial position S1 already illustrated in FIG. 1. The vehicle crane 1 has an alternative configuration, in which its jib 2 has a further fifth connecting point 11a which is located in a region between the first connecting point 7a and the third connecting point 8a. In the present case, in order to achieve a further relieving of the loading on the jib 2 an auxiliary tensile connector or means 11 has been coupled to the fifth connecting point 11a, which is connected at its opposite end to the main tensile connector 7 in a sixth connecting point 11b. In this case, the auxiliary tensile connector 11 extends, starting from the sixth connecting point 11b, at an expedient angle, in particular at a right angle, to the main tensile connector 7, where the auxiliary tensile connector 11 may be constructed in like manner to the main tensile connector 7. The auxiliary tensile connector 11 thus extending between the fifth connecting point 11a and the sixth connecting point 11b on the main tensile connector 7 suspends the empty weight of the jib 2, which acts between the first connecting point 7a and the third connecting point 8a, quasi onto the main tensile connector 7, which, in spite of its natural flexibility in relation to the loading thus introduced therein, contributes to a further partial compensation for the bending moments in the jib 2. Fundamentally, it is also possible to use an auxiliary tensile connector 11 at a different location or to use more than one auxiliary tensile connector 11 which are arranged spaced apart along the jib 2. A first alternative could make provision to position the third connecting point 8a for the individual secondary tensile connector 8 closer to the head 2b of the jib 2 and to provide the fifth connecting point 11a in a region between the third connecting point 8a and the foot 2a of the jib 2.
(15) FIG. 5 shows a second alternative embodiment of the inventive vehicle crane of FIG. 1, in an otherwise identical view. In comparison with FIG. 1, the progression of the secondary tensile connector 8 has been selected differently. The secondary tensile connector 8 is fastened to the jib 2 in its third connecting point 8a at a location comparable to that in FIG. 1. From here, the secondary tensile connector 8 is not guided in the direction of the head 6b of the counter jib 6 as in FIG. 1 but instead, as known from the auxiliary tensile connector 11 of FIG. 4, is guided at an angle of less than 90°, which is inclined in the direction of the counter jib 6, to a seventh connecting point 8c to the main tensile connector 7. This angle can also be 90° if necessary. In the seventh connecting point 8c on the main tensile connector 7, the secondary tensile connector 8 is deflected and guided further in the direction of the foot 2a of the jib 2 in order to be coupled at this location in the region of the foot 2a in an eighth connecting point 8d. Starting from the eighth connecting point 8d, the secondary tensile connector 8 also forms in this case an angle of less than 90° to the jib 2. Since also in this case, in order to adjust the length of the secondary tensile connector 8, the secondary tensile connector 8 is formed, at least between the seventh connecting point 8c and the eighth connecting point 8d, in the manner of a pulley block with a corresponding reeving arrangement, the secondary tensile connector 8 in the eighth connecting point 8d is diverted on the one hand and is guided on the one hand once or multiple times back in the direction of the seventh connecting point 8c and is guided on the other hand further in the direction of the associated winch mechanism on the superstructure 5 or on the foot 6a of the counter jib 6. Fundamentally, it is also possible to arrange a winch mechanism in the region of the foot 2a in order to adjust the length of the secondary tensile connector 8 and thus replace the previously described pulley block-like formation.
(16) FIG. 6 shows a third alternative embodiment of the inventive vehicle crane 1 of FIG. 5 which corresponds substantially to the embodiment shown in FIG. 5. In order to achieve a further relieving of the loading on the jib 2, an auxiliary tensile connector 11 is coupled, in a manner comparable to FIG. 4, between a fifth connecting point 11a on the jib 2 and an opposite sixth connecting point 11b on the main tensile connector 7. In this case, the auxiliary tensile connector 11 extends, starting from the sixth connecting point 11b at a right angle to the main tensile connector 7. The fifth connecting point 11a is located in the region between the third connecting point 8a and the foot 2a of the jib 2. In this case, compared to the alternative shown in FIG. 5, the third connecting point 8a has been moved further in the direction of the head 2b of the jib 2. Fundamentally, it is also possible to use an auxiliary tensile connector 11 at a different location or to use more than one auxiliary tensile connector 11 which are arranged spaced apart along the jib 2.
(17) FIG. 7 shows a fourth embodiment of the inventive vehicle crane 1 of FIG. 2, in an otherwise identical view. In contrast to the view in FIGS. 1 to 6, the vehicle crane 1 is set up without a counter jib 6 designed as a superlift jib and is thus set up only with a counter jib 6′, also referred to as an A-block, with a foot 6a′ and a head 6b′. In this case, the main tensile connector 7 also extends, as shown in the previous FIGS. 1 to 6, starting from the region of the foot 2a of the jib 2 to the opposite head 2b of the jib 2. The progression of the secondary tensile connector 8 is comparable to that of FIG. 5. The secondary tensile connector 8 is fastened to the jib 2 in its third connecting point 8a at a point comparable to that in FIG. 1. From here, the secondary tensile connector 8 is not guided in the direction of the head 6a′ of the counter jib 6′ but instead is guided at an angle of less than 90°, which is inclined in the direction of the counter jib 6′, to a seventh connecting point 8c to the main tensile connector 7. This angle can also be 90° if necessary. In the seventh connecting point 8c on the main tensile connector 7, the secondary tensile connector 8 is deflected and guided further in the direction of the foot 2a of the jib 2 in order to be coupled at this location in an eighth connecting point 8d. Starting from the eighth connecting point 8d, the secondary tensile connector 8 also forms in this case an angle of less than 90° to the jib 2. Since also in this case, in order to adjust the length of the secondary tensile connector 8, the secondary tensile connector 8 is formed, at least between the seventh connecting point 8c and the eighth connecting point 8d, in the manner of a pulley block with a corresponding reeving arrangement, the secondary tensile connector 8 in the eighth connecting point 8d is deflected on the one hand and is guided on the one hand once or multiple times back in the direction of the seventh connecting point 8c and is guided on the other hand further in the direction of the associated winch mechanism 14 on the superstructure 5 or on the foot 6a′ of the counter jib 6′.
(18) In conjunction with the invention, the main tensile connector 7 and also the secondary tensile connector 8 can each be articulated to the tip of the head 2b of the jib 2 or the head 6b, 6b′ of the counter jib 6, 6′ or in the region thereof. The term region is hereby understood to be a portion starting from the respective outer end of the jib 2, 6, 6′ inwards with a length of up to 10% of the entire length of the respective jib 2, 6, 6′. The same applies to the connecting points on the foot 2a, 6a, 6a′ of the jib 2, 6, 6′.
(19) In conjunction with the previously described exemplified embodiments shown in FIGS. 1 to 7, the third connecting point 8a for the secondary tensile connector 8 is illustrated in the drawings always in the region of a top chord of the jib 2 designed as a lattice mast. For this purpose, it is fundamentally also possible for this third connecting point 8a to also be arranged in the region of a bottom chord of the jib 2 or in its so-called system centre line.
