Extendible crane boom formed of telescopic box-shaped sections

Claim 2

A longitudinally extendible crane boom comprising a first boom section forming the base of said boom and a plurality of second boom sections telescopically positionable within said first boom section and extendible from said first boom section in a serially arranged manner, each of said second boom sections having a first end and a second end spaced longitudinally from the first end thereof with said first end located closer to the base of said boom than said second end thereof, each said second boom having a U-shaped configuration comprising a pair of longitudinally extending laterally spaced members and the bight portion of the U-shaped member comprising a member secured to and extending transversely of one end of said longitudinally extending members, said longitudinally extending members fitted in the retracted position within said longitudinally extending members of said boom sections located closer to the base of said boom in the extended position, wherein the improvement comprises that said longitudinally extending members are box-shaped with each having a trapezoidally shaped cross-section and in the horizontal position of the boom and upper and lower sides of the trapezoidally shaped cross-section are arranged in parallel and said lower side being narrower in the transverse direction than said upper side, said transverse member is a bending resistant member, and each said second boom section comprises a hydraulic piston cylinder extending in the longitudinal direction of said boom and said hydraulic piston cylinders of said second boom sections are located in the longitudinally extending spaces between said box-shaped members of said second boom sections.

Claim 3

A longitudinally extendible crane boom, as set forth in claim 1, wherein said box-shaped members of said second boom sections are disposed in parallel relationship to one another.

Claim 4

A longitudinally extendible crane boom, as set forth in claim 1, wherein said transverse member connecting the ends of said box-shaped members is located at the ends of said box-shaped members more remote from the base of said boom.

Claim 5

A longitudinally extendible crane boom, as set forth in claim 3, wherein at least one stiffening member is provided on the ends of said box-shaped members located opposite the ends thereof to which said transverse members are secured.

Claim 6

A longitudinally extendible crane boom, as set forth in claim 3, wherein said first boom section comprises a single longitudinally extending box-shaped member and a bending resistant member secured to and extending transversely of the end of said single box-shaped member outwardly from the base of said boom, rollers are positioned on the upper surfaces of the ends of said second boom members spaced from the end at which said transverse member is located, said rollers arranged to run on the upper inner surface of the adjacent said boom section located closer to the base of said boom in the extended position, guides are provided on the inner upper surface of said box-shaped member of said first boom section with said guides disposed at an angle of 45* relative to the upper surface of said box-shaped members of said second boom sections, and said guides being arranged to contact said next outwardly located said second boom section.

Claim 7

A longitudinally extendible crane boom, as set forth in claim 1, wherein said first boom section comprises a pair of longitudinally extending laterally spaced box-shaped members having the axes thereof disposed in parallel relationship and a bending resistant member secured to and extending transversely of the ends of said box-shaped members at the end of said first boom section spaced outwardly from the base of the boom.

Claim 8

A longitudinally extendible crane boom, as set forth in claim 1, wherein said first boom section comprises a single longitudinally extending laterally closed box-shaped member and a bending resistant member secured to and extending transversely of the end of said single box-shaped member spaced outwardly from the base of said boom.

Claim 9

A longitudinally extendible crane boom, as set forth in claim 1, wherein rollers are positioned on the upper surfaces of the ends of said second boom members spaced from the end at which said transverse member is located, said rollers arranged to run on the upper inner surfaces of the adjacent said boom section located closer to the base of said boom in the extended position, rollers positioned on each of said transverse members of said second boom members with said rollers located on the lower side of said transverse members, and each said second boom section having a running surface on its underside for running on said rollers of said transverse members of the adjacent said boom section closer to the base of said boom.

Claim 10

A longitudinally extendible crane boom, as set forth in claim 8, wherein said lower side of each of said box-shaped members of said second boom sections forms a running surface which cooperates with said rollers on said transverse member of the adjacent said boom section located closer to the base of the boom in the extended position, the axes of said rollers on said transverse member are disposed in parallel relationship with the lower sides of said box members of said second boom sections and the upper sides of each of said box members of said second boom sections has a pair of surfaces along the opposite edges thereof arranged at an inclined position to the upper surface and extending from the upper surface to the side surfaces of said box-shaped members and the inclined surfaces arranged at an acute angle to the upper and lower surfaces of said box-shaped members with each inclined edge surface of said upper side forming a running surface in contact with said rollers on the first ends of said second boom sections which said rollers have their axes extending in parallel relationship with the inclined edge surfaces of the upper side.

Claim 11

A longitudinally extendible crane boom, as set forth in claim 1, wherein each said box-shaped member of said second boom sections in the horizontal position of the boom comprises an upper U-shaped longitudinally extending sheet metal section and a lower U-shaped longitudinally extending sheet metal section with the openings of said upper and lower U-shaped sections facing toward one another and the longitudinal edges of the free ends of said upper and lower U-shaped sections being welded together.

Claim 12

A longitudinally extendible crane boom, as set forth in claim 10, wherein said lower U-shaped section having a greater material thickness than said upper U-shaped section.

Claim 13

A longitudinally extendible crane boom, as set forth in claim 1, wherein each said hydraulic piston cylinder comprises a housing and a piston rod extendible from said housing, the free end of each said piston rod which projects from said housing is connected to said transverse member of one of said second boom sections and its housing is secured at its end from which said piston rod projects to said transverse member of said second boom section next closer to the base of said boom in the extended position.

Claim 14

A longiTudinally extendible crane boom, as set forth in claim 12, wherein each said housing of said hydraulic piston cylinders has a longitudinally extending guide, and a roller positioned on the next outwardly disposed housing at the end spaced from the end from which the piston rod extends so that said roller rides in said guide as said second boom sections are extended and retracted.

Claim 15

A longitudinally extendible crane boom, as set forth in claim 1, wherein the innermost said hydraulic piston cylinder in the extended position of said boom is secured at the end of its housing opposite the end from which said piston rod extends to said transverse member of said second boom section located adjacent said base boom section in the extended position of said boom and the free end of said piston rod is secured to said base boom section.

Claim 16

A longitudinally extendible crane boom comprising a first boom section forming the base of said boom and a plurality of second boom sections telescopically positionable within said first boom section and extendible from said first boom section in a serially arranged manner, each of said second boom sections having a first end and a second end spaced longitudinally from the first end thereof with said first end located closer to the base of said boom than said second end thereof, each said second boom having a U-shaped configuration with the legs of the U-shaped configuration comprising a pair of longitudinally extending laterally spaced members and the bight portion of the U-shaped member comprising a member secured to and extending transversely of one end of said longitudinally extending members, said longitudinally extending members fitted in the retracted position within said longitudinally extending members of said boom sections located closer to the base of said boom in the extended position, wherein the improvement comprises that said longitudinally extending members are box-shaped with each having a trapezoidally shaped cross-section and in the horizontal position of the boom the upper and lower sides of the trapezoidally shaped cross-section are arranged in parallel and said lower side being narrower in the transverse direction than said upper side, said transverse member is a bending resistant member, said first boom section comprises a pair of longitudinally extending laterally spaced box-shaped members having the axis thereof disposed in parallel relationship and said bending resistant member secured to and extending transversely of the ends of said box-shaped members at the end of said first boom sections spaced outwardly from the base of the boom, each said second boom comprises a hydraulic piston cylinder extending in longitudinally direction of said boom and said hydraulic piston cylinders of said second boom sections are located in longitudinally extending spaces between box-shaped members of said second boom sections, a support guide secured to and extending inwardly from the inwardly facing side surfaces of said box members of said first boom section, and rollers secured to the sides of said innermost hydraulic piston cylinder in the extended position of said boom and fitted into said support guides on said box members of said first boom section.

Claim 17

A longitudinally extendible crane boom comprising a first boom section forming the base of said boom and a plurality of second boom sections telescopically positionable within said first boom section and extendible from said first boom section in a serially arranged manner, each of said second boom sections having a first end and a second end spaced longitudinally from the first end thereof with said first end located closer to the base of said boom than said second end thereof, each said second boom having a U-shaped configuration with the legs of the U-shaped configuration comprising a pair of longitudinally extending laterally spaced members and the bight portion of the U-shaped member comprising a member secured to and extending transversely of one end of said longitudinally extending members, said longitudinally extending members fitted in the retracted position within said longitudinally extending members of said boom sections located closer to the base of said boom in the extended position, wherein the improvement comprises that said longitudinally extending members are box-shaped with each having a trapezoidally shaped cross-section and in the horizontal position of the boom the upper and lower sides of the trapezoidally shaped cross-section are arranged in parallel and said lower side being narrower in the transverse direction than said upper side, said transverse member is a bending resistant member, said first boom section comprises a pair of longitudinally extending laterally spaced box-shaped members having the axis thereof disposed in parallel relationship and said bending resistant member secured to and extending transversely of the ends of said box-shaped members at the end of said first boom sections spaced outwardly from the base of the boom, each said second boom comprises a hydraulic piston cylinder extending in longitudinally direction of said boom and said hydraulic piston cylinders of said second boom sections are located in longitudinally extending spaces between box-shaped members of said second boom sections, a support guide secured to and extending inwardly from the inwardly facing side surfaces of said box members of said first boom section, and rollers secured to the sides of said innermost hydraulic piston cylinder in the extended position of said boom and fitted into said support guides on said box members of said first boom section.