Crane

Claim 2

In a mobile tower crane the combination comprising: a mobile carrier; a power unit superstructure revolvably mounted on said carrier; a main boom having its lower end pivotably attached to the forward end of said superstructure; a pair of rigid, spaced apart, fixed length, diagonal brace members, each possessing a large moment of inertia and having its upper end pivotably attached to opposite sides of said main boom adjacent the upper end thereof and its lower end detached from said superstructure when said main boom is in a substantially horizontal position and attached to said superstructure adjacent the rear end thereof when said main boom is in a substantially vertical operating position to form a tripod shaped, rigidly braced structure; a secondary boom having its lower end pivotably coupled to the upper end of said main boom; elevating means to raise said main boom, diagonal brace members, and secondary boom from a substantially horizontal position into the operating position; and means to raise and lower said secondary boom when in the operating position.

Claim 3

The combination set forth in claim 1 wherein said main boom is constructed from a plurality of generally rectangular sections each having four longitudinally extending main cord members.

Claim 4

The combination set forth in claim 1 wherein said diagonal brace members are connected to said main boom through a transverse strut carried by said main boom.

Claim 5

The combination set forth in claim 1 wherein said secondary and main booms are coupled by means of a connecting structure having an upper flat plate pivotably connected to said secondary boom and a lower flat plate fixedly attached transversely to the top of said main boom, said plates being in abutting relationship when said crane is in the operating position, and said plates being pivotably connected adjacent one edge thereof.

Claim 6

The combination set forth in claim 1 wherein said elevating means includes a rigid erecting gantry having its lower end pivotably attached to said superstructure adjacent the base of said main boom and its upper end attached to each of said diagonal brace members.

Claim 7

The combination set forth in claim 1 wherein said lower ends of said diagonal braces are attached to said superstructure by means of a transverse strut member carried by said superstructure.

Claim 8

The combination set forth in claim 4 wherein said secondary boom is attached to said main boom through a bifuricated foot section pivotably attached to the top of said upper flat plate.

Claim 9

The combination set forth in claim 4 wherein said secondary boom is attached to said upper flat plate at approximately the middle of said upper flat plate.

Claim 10

The combination set forth in claim 4 wherein said upper and lower plates are pivotably connected at their forward edges.

Claim 11

The combination set forth in claim 4 wherein said main boom terminates in a section having four main spaced apart cord members; said lower plate being attached to the ends of said cords and pivotably connected at its forward edge to the forward edge of said upper plate; said secondary boom being pivotably attached to the top of said upper plate at points on a line through the middle of said upper plate through upstanding brackets fixed to the top surface of said upper plate.

Claim 12

The combination set forth in claim 4 wherein an upper gantry is pivotably attached at its lower end to the upper plate of said connecting structure, said gantry having pendant lines attached to its upper end, said pendant lines being connected to the outer end of said secondary boom, said upper end of said gantry being connected through a reeving system to power means whereby said secondary boom can be raised and lowered when the crane is in the substantialLy vertical operating position.

Claim 13

In a mobile tower crane the combination comprising: a mobile carrier; a power unit superstructure revolvably mounted on said carrier; a main boom made up of individual sections coupled together and having its lower section pivotably attached to the forward end of said superstructure and its upper end attached to a connecting structure; a rigid, fixed length, first diagonal brace member pivotably attached at its upper end to one side of the upper end of said main boom; a rigid, fixed length, second diagonal brace member pivotably attached at its upper end to the other side of the upper end of said main boom and spaced apart from said first diagonal member, each of said diagonal members having their spaced apart lower ends attached to the rear of said superstructure; said braces possessing a large moment of inertia; a secondary boom made up of individual sections coupled together, said boom having its lower end pivotably coupled to said connecting structure; a reeving system coupled to said power unit and having a floating link at its upper end; a first pair of pendant lines coupling said floating link to an upper gantry pivotably mounted on said connecting structure, a second pair of pendant lines connecting said upper gantry to the upper end of said secondary boom; and load hoisting means including a load line running from said power unit over a sheave carried by said connecting structure and through a sheave carried by the end of said secondary boom.

Claim 14

In a mobile tower crane the combination comprising: a mobile carrier; a power unit superstructure revolvably mounted on said carrier; a main boom made up of individual sections coupled together and having its lower section pivotably attached to the forward end of said superstructure and its upper end attached to a connecting structure; a rigid, fixed length, first diagonal brace member pivotably attached at its upper end to one side of the upper end of said main boom; a rigid, fixed length, second diagonal brace member pivotably attached at its upper end to the other side of the upper end of said main boom and spaced apart from said first diagonal member, each of said diagonal members having their spaced apart lower ends attached to the rear of said superstructure; said braces possessing a large moment of inertia; a secondary boom made up of individual sections coupled together, said boom having its lower end pivotably coupled to said connecting structure; a reeving system coupled to said power unit and having a floating link at its upper end; a first pair of pendant lines coupling said floating link to an upper gantry pivotably mounted on said connecting structure, a second pair of pendant lines connecting said upper gantry to the upper end of said secondary boom; and load hoisting means including a load line running from said power unit over a sheave carried by said connecting structure and through a sheave carried by the end of said secondary boom.