Structural design of boom section with inverted {37 a{38 {11 frame cross-section

Claim 2

In combination in a crane: a support; a boom having at least one hollow boom section mounted for vertical pivotal movement on said support; and boom hoist means for effecting vertical pivotal movement of said boom, said boom section comprising: a top plate defining an upper side of said boom section, which upper side is the side furthest away from said support, a bottom plate narrower than said top plate and defining a lower side of said boom section, which lower side is the side closest to said support, and two side plates connected between the lower surface of the top plate and the upper surface of the bottom plate, each side plate being wider than said bottom plate, and each side plate defining an angle between its inner surface and the upper surface of said bottom plate which is greater than 90* but less than 120*.

Claim 3

A combination according to claim 1 including two elongated side plate stiffeners, each extending along the length of said boom section and connected between the outer surface of one side plate and said bottom plate.

Claim 4

A combination according to claim 2 wherein each side plate stiffener connects to its respective side plate along a line which is approximately 1/6 of the width of the side plate above said bottom plate to thereby increase the buckling strength of said side plate by a factor of approximately five.

Claim 5

A combination according to claim 3 and wherein said one boom section is fabricated of steel plate, wherein said two side plates are welded between the lower surface of said top plate and the upper surface of said bottom plate, and wherein each of said side plate stiffeners is welded to the outer surface of its associated side plate and to an edge of said bottom plate.

Claim 6

A combination according to claim 4 wherein said one boom section is a base section and wherein said boom hoist means comprises a pair of boom hoist cylinders on opposite sides of said boom and connected between said support and said boom base section and spaced from each other a distance greater than the width of the bottom side of the boom but less than the width of the top side of said boom whereby said boom base section nests therebetween when in lowered position.

Claim 7

In combination in a crane: a support; a telescopic boom comprising a hollow base section and at least one other hollow section mounted for telescopic movement with respect to said base section; means for pivotally connecting said base section to said support to enable vertical pivotal movement of said boom; means for extending and retracting said other boom section with respect to said base section; boom hoist means connected to and between said support and said base section for effecting vertical pivotal movement of said boom to raise and lower said boom; external slide pads located at the upper rear end of said other section; and internal slide pads located inside of and near the forward lower end of said base section; each of said boom sections comprising: a top plate defining an upper side of said one boom section, which upper side is the side furthest away from said support, a bottom plate narrower than said top plate and defining a lower side of said one boom section, which lower side is the side closest to said support, two side plates connected between the lower surface of the top plate and the upper surface of the bottom plate, each side plate being wider than said bottom plate, and each side plate defining an angle between its inner surface and the upper surface of said bottom plate which is greater than 90* but less than 120*; and two elongated side plate stiffeners, each extending along the length of said boom section and connected between the outer surface of one side plate and said bottom plate.

Claim 8

In combination in a crane: a support; a telescopic boom comprising a hollow base section and at least one other hollow section mounted for telescopic movement with respect to said base section; means for pivotally connecting said base section to said support to enable vertical pivotal movement of said boom; means for extending and retracting said other boom section with respect to said base section; boom hoist means connected to and between said support and said base section for effecting vertical pivotal movement of said boom to raise and lower said boom; external slide pads located at the upper rear end of said other section; and internal slide pads located inside of and near the forward lower end of said base section; each of said boom sections comprising: a top plate defining an upper side of said one boom section, which upper side is the side furthest away from said support, a bottom plate narrower than said top plate and defining a lower side of said one boom section, which lower side is the side closest to said support, two side plates connected between the lower surface of the top plate and the upper surface of the bottom plate, each side plate being wider than said bottom plate, and each side plate defining an angle between its inner surface and the upper surface of said bottom plate which is greater than 90* but less than 120*; and two elongated side plate stiffeners, each extending along the length of said boom section and connected between the outer surface of one side plate and said bottom plate.

Claim 9

A combination according to claim 6 including support means for said external slide pads comprising: a slide pad support plate connected to the top edges of said side plates, an inner brace below and spaced from said slide pad support plate and connected to the inner surfaces of said side plates, and a plurality of vertical braces secured to and between said slide pad support plate and said inner brace.

Claim 10

A combination according to claim 7 including support means for said internal slide pads comprising: a suPport connected to the inner surfaces of said side plates, a horizontal brace below and spaced from said support and connected to the inner surfaces of said side plates, and a plurality of vertical braces secured to and between said support and said horizontal brace.

Claim 11

In combination in a mobile crane: a support; a telescopic boom comprising a hollow base section and a plurality of other hollow sections mounted for telescopic movement with respect to said base section; means for pivotally connecting said base section to said support to enable vertical pivotal movement of said boom; means for extending and retracting said other boom section with respect to said base section; external slide pads located at the upper rear end of each of said other sections; and internal slide pads located inside of and near the forward lower end of said base section and at least some of said other sections; each of said boom sections being fabricated of steel plate and comprising: a top plate defining an upper side of said one boom section, which upper side is the side furthest away from said support, a bottom plate narrower than said top plate and defining a lower side of said one boom section, which lower side is the side closest to said support, two side plates welded between the lower surface of the top plate and the upper surface of the bottom plate, each side plate being wider than said bottom plate, and each side plate defining an angle between its inner surface and the upper surface of said bottom plate which is greater than 90* but less than 120*; two elongated side plate stiffeners, each extending along the length of said boom section and welded between the outer surface of one side plate and said bottom plate; and boom hoist means connected to and between said support and said base section for effecting vertical pivotal movement of said boom to raise and lower said boom, said boom hoist means comprising a pair of boom hoist cylinders on opposite sides of said boom and connected between said support and said boom base section and spaced from each other a distance greater than the width of the bottom side of the boom base section but less than the width of the top side of said boom base section whereby said boom base section nests therebetween when in lowered position.

Claim 12

In combination in a mobile crane: a support; a telescopic boom comprising a hollow base section and a plurality of other hollow sections mounted for telescopic movement with respect to said base section; means for pivotally connecting said base section to said support to enable vertical pivotal movement of said boom; means for extending and retracting said other boom section with respect to said base section; external slide pads located at the upper rear end of each of said other sections; and internal slide pads located inside of and near the forward lower end of said base section and at least some of said other sections; each of said boom sections being fabricated of steel plate and comprising: a top plate defining an upper side of said one boom section, which upper side is the side furthest away from said support, a bottom plate narrower than said top plate and defining a lower side of said one boom section, which lower side is the side closest to said support, two side plates welded between the lower surface of the top plate and the upper surface of the bottom plate, each side plate being wider than said bottom plate, and each side plate defining an angle between its inner surface and the upper surface of said bottom plate which is greater than 90* but less than 120*; two elongated side plate stiffeners, each extending along the length of said boom section and welded between the outer surface of one side plate and said bottom plate; and boom hoist means connected to and between said support and said base section for effecting vertical pivotal movement of said boom to raise and lower said boom, said boom hoist means comprising a pair of boom hoist cylinders on opposite sides of said boom and connected between said support and said boom base section and spaced from each other a distance greater than the width of the bottom side of the boom base section but less than the width of the top side of said boom base section whereby said boom base section nests therebetween when in lowered position.