A system for reducing the overall aerial dimensions of the jib in a foldable jib crane

Abstract

 The invention relates to a system for partial folding the jib distal section (8) of a foldable tower crane (2, 3, 4) so as to allow the free training of the crane jib (6, 8) in presence of wind, without said jib interfering with any surrounding obstacles, said system comprising a tip (11) deformable under the action of a hydraulic cylinder (11b) and a metallic cable (10) located between said tip (11) and said jib distal section (8).

Description

[0001] This invention relates to a system for reducing the overall aerial dimensions of the jib in a foldable tower crane.

[0002] More precisely the invention relates to a system for partially folding the jib of a foldable tower crane so that the jib can freely swing under the wind force without said jib interfering with any surrounding obstacle.

[0003] A foldable tower crane is known, e.g. from Italian Patents No. 1179987 and No. 1206882 in the name of the applicant.

[0004] These patents disclose systems for controlling the straightening and folding of a foldable tower crane comprising a vertical crane formed by two sections and a horizontal jib, which is formed by two sections as well.

[0005] Both the above mentioned patents refer to a system for folding a crane to facilitate the crane transportation or to reduce the crane dimensions during idle periods.

[0006] According to current regulations cranes installed in yards must be let free to turn according to wind direction so as to offer a minimum resistance. In other words the horizontal jib of a crane must be free to rotate by about 360° to align itself with the wind direction.

[0007] The site where a crane has been installed not always allows such jib training (rotation), for example because of the presence of masonry obstacles or antennas for radio and TV reception. In such situations it becomes mandatory to fold the crane at the end of each dayworks.

[0008] This drawback is especially common in city centres, where cranes are often to be installed in tight spaces.

[0009] It is an object of the present invention to solve the problem of allowing a free training of a crane jib without interfering with the surrounding obstacles.

[0010] Another object of the present invention is to provide a system for partially folding the distal portion of the horizontal jib in a crane, with such system that can be easily fitted to a foldable tower crane of the type disclosed in Italian Patent No. 1 206 882.

[0011] The above and other objects of the present invention are achieved by a system as claimed in the attached claims.

[0012] The above objects will be better understood from the following detailed description of an embodiment of the invention with particular reference to the accompanying drawings in which:

Figure 1 is a schematic side view of a crane provided with a system for reducing the overall aerial dimensions according to the invention;

Figure 2a is a schematic view of the system for reducing the overall aerial dimensions according to the invention, with the crane in an operating configuration;

Figure 2b is a schematic view of the system for reducing the overall aerial dimensions according to the invention, with the crane jib in a free training configuration;

Figure 3 is a enlarged side view of a detail according to the invention;

Figure 4 is a plan view of the detail of Figure 3.

[0013] Figure 1 shows a foldable crane substantially formed by a tower mounted on a base 1 and formed by two sections 2 and 4, pivoted to each other at 3, and a jib mounted at the tower top and formed by two sections 6 and 8 pivotally connected to each other at 5.

[0014] The crane tower is provided with actuating means 7 through which the crane tower can be raised or lowered, and with other well known components and devices that will not be described in details.

[0015] Referring now to Figures 2a and 2b, the system for reducing the overall aerial dimensions of a foldable tower crane jib according to the invention comprises a deformable tip 11 having a substantially pyramidal shape, provided on the top section 4 of the crane tower. Tip 11 is deformable in that its configuration can be modified.

[0016] Such tip 11 comprises a metal frame formed by a pair of tubular members 11a and a hydraulic cylinder 11b.

[0017] The tubular members 11a are arranged to form a triangle, with an end of each tubular member being hinged or pivotally coupled to the tower top at 11c, and with the other ends of such tubular members pivoted to each other at 11d.

[0018] The case 200 of hydraulic cylinder 11b is pivotally connected (at 11e) to the top of the tower, while the piston rod 201 of the hydraulic cylinder 11b is pivotally connected (at 11d) to the jointed ends of said tubular members 11a.

[0019] The folding system according to the invention further comprises a cable 10, having one end secured to the pivot point 11d, and the other end secured to the distal section 8 of the crane jib, through a bracket 12 disposed near the jib pivot(s) 5 rotatably connecting together the proximal section 6 with the distal section 8 of the crane jib.

[0020] An articulated supporting member or swinging holder 13 is provided at pivot 5, as better shown in Figures 2 and 3, for joining together a pair of headropes 25.

[0021] Referring how to Figures 3 and 4, the articulated supporting member 13 comprises two pairs of beams 14, 15 and 16, 17, with the ends of each beam connected together in a V configuration, disposed in parallel planes and provided with holes 18 and 18' at the vertex of each pair for a rotatable connection to pivots 5 of jib 3.

[0022] The pairs of V-shaped beams 14, 15 and 16, 17 are jointed by a ledger 20 having a cantilever fork 21 secured to its middle and carrying a rotatable pulley 23 for guiding the tie cable 10 when this latter engages the pulley 23.

[0023] At the other ends of beams 14, 16 there are formed holes 24 and 24', to each of which is fixed an end of a tie cable 25, 25'. The opposite end of each tie cable 25, 25' in turn is fixed to a structure 27 integral with the top of the crane tower and extending above said deformable tip 11.

[0024] Beams 14 and 16 are further jointed by a stiffening bar 22, and beams 16 and 17 are jointed by a stiffening bar 19.

[0025] The pair of cables 25 and 25' is driven by the lifting of the structure 27 as described in Italian Patent No. 1206882.

[0026] Further according to the disclosure of said patent, the tractive force applied by cables 25 and 25' accomplishes the folding or extending of jib thanks to the rotation of the jib distal section 8 around jig pivots 5.

[0027] According to the present invention, the forward (extending) and backward (contracting) motion of rod 201 inside the case 200 of the hydraulic cylinder 11b modifies the shape of tip 11 which takes a backward or a forward configuration in respect of the crane jib 6, 8.

[0028] Advantageously, thanks to the system according to invention, when the crane is fully extended, the jib distal section 8 can achieve an operating configuration with a forward projecting configuration of tip 11 as shown in Figure 2a, or a rest configuration with a backward configuration of said tip as shown in Figure 2b.

[0029] In the rest configuration shown in Figure 2b, the crane range is reduced while the jib distal section 8 is inclined with respect to the jib section 6, and the end thereof has been raised. The angle of jig section 8 with respect to the horizontal operating plane is comprised between 0° and 90° without reaching such limits.

[0030] This way, the risk that the crane jib can interfere with surrounding obstacles is considerably reduced and the crane jib can freely rotate by 360° in presence of wind.

Claims

1. A system for reducing the overall aerial dimensions of a jib (6, 8) in a foldable tower crane (2, 3, 4) provided with a horizontal jib formed by a proximal section (6) and a distal section (8) pivotally connected to each other at a pivot point (5), characterised in that it comprises means (10, 11) for pivotally rotating said distal section (8) with respect to said proximal section (6) when said crane is in an operating position.

2. A system according to claim 1, wherein said pivotal rotation occurs in a vertical plane, and said operating position corresponds to a configuration where said proximal section (6) is in a substantially horizontal position and said crane tower (2, 4) is in a vertical position.

3. A system according to claim 2, wherein said pivotal rotation is an upwardly directed rotation.

4. A system according to any preceding claims, wherein said rotation means (10, 11) can assume a first configuration where said distal section (8) is aligned with respect to said proximal section (6), and a second configuration where said distal section (8) is in a slant position with respect to said proximal section (6).

5. A system according to claim 4, wherein said slanted direction forms an angle comprised between 0° and 90°, the upper and lower limits being excluded, with respect to the horizontal operating plane of said jib (6, 8).

6. A system according to any preceding claims, wherein said rotation means (10, 11) comprises a deformable tip (11) secured to an end of a tie rod (10), the opposite end of said tie rod (10) being secured to said jib distal section (8).

7. A system according to claim 6, wherein said tip (11) comprises a frame formed by tubular members (11a, 11b) pivotally connected to each other.

8. A system according to claim 7, wherein said frame further comprises a hydraulic cylinder (11b).

9. A system according to claim 6, wherein said tip (11) is located on the top of said crane tower (2,4).

10. A system according to claim 9, wherein under the action of said hydraulic cylinder (11b) said tip (11) can assume a forward projecting position with respect to said jib (6, 8), corresponding to the crane operating position, and a backward position with respect to said jib (6, 8) corresponding to a free training position of said crane.

11. A system according to claim 10, wherein said tip (11) and said jib distal section (8) are further provided with means (23) for guiding said tie rod (10).

12. A system according to claim 11, wherein said guide means (23) comprise a pulley rotatably mounted to a holder (13) provided in correspondence of said jib pivot point (5), between said proximal section (6) and said jib distal section (8), and wherein said tie rod (10) is a metal cable.

13. A system according to any of claims 1 to 5, wherein said rotation means comprise:

- a hydraulic cylinder (11b) having a first end pivotally coupled to the tower crane top;

- a pair of tubular members (11a) each having one end (11c) pivotally coupled to the tower crane top and the opposite end (11d) pivotally coupled to the second end of said hydraulic cylinder (11b);

- a cable (10) having one end fixed to the pivotal connection (11d) between said cylinder (11b) and said tubular members (11a), and the opposite end fixed to the distal section (8) of said jib;

- a swinging holder (13) of a substantially pyramidal shape, having a vertex connected to said pivot point (5) between said proximal section (6) and said jib distal section (8), said swinging holder (13) comprising a pulley (23) for guiding said cable (10) during the rotation of said jib distal section (8) under the action of said hydraulic cylinder (11b).

14. A foldable tower crane incorporating a system for reducing the overall aerial dimensions of the jib according any of the preceding claims.

Drawing