Telescopic jib for a vehicular crane

1. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts comprises an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape, and

said upper profile part consists of a plurality of adjacent shell segments having an outwardly curved shape, the end portions of adjacent segments of said upper profile part meeting each other at an obtuse angle.

2. The telescopic jib as set forth in claim 1 , wherein said upper profile part and said lower profile part each consists of at least three shell segments.

3. The telescopic jib as set forth in claim 1 , wherein each of said curved shell segments is configured at least partially in the shape of a circular arc.

4. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts comprises an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape;

said upper profile part consists of a plurality of adjacent shell segments having an outwardly curved shape, the ends of adjacent segments of said upper profile part meeting each other at an obtuse angle;

wherein the endmost segments of said upper and lower profile parts comprise free ends formed as straight legs, and said upper and lower profile parts are welded to each other at their adjacent straight legs.

5. The telescopic jib as set forth in claim 4 , wherein the straight legs of said upper profile part and said lower profile part are welded in the area of the neutral zone of said at least one jib part.

6. The telescopic jib as set forth in claim 3 , wherein that at least some of said curved shell segments of said upper profile part each have the shape of a circular arc with respectively differing radii of curvature.

7. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts comprises an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape, and

said upper profile part consists of a plurality of adjacent shell segments having an outwardly curved shape, the end portions of adjacent segments of said upper profile part meeting each other at an obtuse angle and at least one intervening straight segment interposed between two of said segments having an outwardly curved shape.

8. The telescopic jib as set forth in claim 7 , wherein

said at least one intervening straight segment of said upper profile part is a central straight segment,

and said plurality of adjacent shell segments of said upper profile part having an outwardly curved shape include a first outwardly curved shell segment on each side of said central straight segment, said first outwardly curved segments having a relatively small radius of curvature, and

a second outwardly curved shell segment adjacent each said first outwardly curved shell segment, each of said second outwardly curved shell segments having a relatively large radius of curvature.

9. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts consists essentially of an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape, and

said upper profile part consists of a pair of shell segments having an outwardly curved shape, and an intervening straight segment interposed between said outwardly curved segments.

10. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts comprises an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape;

said upper profile part consists of a pair of shell segments having an outwardly curved shape, and an intervening straight segment interposed between said outwardly curved segments

wherein the endmost segments of said upper and lower profile parts comprise free ends formed as straight legs, and said upper and lower profile parts are welded to each other at their adjacent straight legs.

11. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts comprises an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape, and

said upper profile part consists essentially of a central straight segment, a first outwardly curved shell segment on each side of said central straight segment, said first outwardly curved segments having a relatively small radius of curvature, and a second outwardly curved shell segment adjacent each said first outwardly curved shell segment, each of said second outwardly curved shell segments having a relatively large radius of curvature.

12. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts consists of an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape, and

said upper profile part comprises a pair of first outwardly curved shell segments, said first outwardly curved segments having a relatively small radius of curvature, and a second pair of outwardly curved shell segments adjacent said respective first outwardly curved shell segments, each of said second outwardly curved shell segments having a relatively large radius of curvature.

13. A telescopic jib for a crane, said telescopic jib comprising a base jib part supported on said crane and a retractable and extensible telescopic jib part supported by said base jib part, wherein

at least one of said jib parts consists of an upper profile part and a lower profile part,

said lower profile part consists of a plurality of adjacent shell segments each having an outwardly curved shape, and

said upper profile part comprises at least a first outwardly curved shell segment having a relatively small radius of curvature, and a pair of outwardly curved shell segments having a relatively large radius of curvature.