Crane

Claim 2

A crane, comprising a pair of longitudinally spaced portals each having at least two uprights provided with upper end portions connected by a traverse, and with lower end portions; longitudinally extending structural members connecting said portals to form therewith a self-supporting structure; displacing means at said lower end portions for displacing said structure along the ground; at least a pair of load-engaging elements pivotably connected to and depending from each traverse, said elements each comprising a hydraulic cylinder connected to the respective traverse, a piston displaceable in said cylinder and having an outwardly projecting piston rod provided with a free end, and an engaging portion on said free end for engaging a load; and a hydraulic system for said elements, comprising a plurality of hydraulic circuits each associated with one of said elements, central control means associated with all of said circuits for operating all of said elements in unison, and individual control means comprising individual valves each located on one of said uprights and interposed in said circuits for operating said elements individually.

Claim 3

A crane as defined in claim 1, said hydraulic system further comprising a pump, and a drive for said pump; and a control platform suspended from at least one of said structural members intermediate said portals and located proximal to the ground, said control platform supporting thereon said pump, drive and central control means of said hydraulic system.

Claim 4

A crane as defined in claim 1, said displacing means comprising a plurality of wheel units.

Claim 5

A crane as defined in claim 3, each of said wheel units comprising a bifurcated wheel support, pivot means mounting the respective wheel support to one of said lower end portions for vertical movement about a pivot axis, and at least one wheel mounted in the respective bifurcated wheel support.

Claim 6

A crane as defined in claim 4; and further comprising a plurality of cylinder and piston units each carried by one of said uprights and cooperating with one of said wheel units in a sense effecting, when operated, pivotal displacement of the respective unit in a substantially vertical plane from a raised position to a lowered ground-engaging position.

Claim 7

A crane, comprising a pair of longitudinally spaced portals each having at least two uprights provided with upper end portions connected by a traverse, and with lower end portions; longitudinally extending structural members connecting said portals to form therewith a self-supporting structure; displacing means at said lower end portions for displacing said structure along the ground; at least a pair of load-engaging elements pivotably connected to and depending from each traverse, said elements each comprising a double-acting hydraulic cylinder connected to the respective traverse, a piston displaceable in said cylinder and having an outwardly projecting piston rod provided with a free end, and an enegaging portion on said free end for engaging a load; a hydraulic system for said elements, comprising a plurality of hydraulic circuits each associated with one of said elements, central control means associated with all of said circuits for operating all of said elements in unison, and individual control means each associated with one of said circuits for operating said elements individually; arresting means for arresting said cylinders in upright orientation; and extension sections connectable with said piston rods for extending the length thereof so that, at the will of an operator, said elements may be used without said extension sections for engaging a load, or be arrested in upright orientation and connected with one of said sections.

Claim 8

A crane, comprising a pair of longitudinally spaced portals each having at least two uprights provided with upper end portions connected by a traverse, and with lower end portions; longitudinally extending structural members connecting said portals to form therewith a self-supporting structure; displacing means at said lower end portions for displacing said structure along the ground; at least a pair of load-engaging elements pivotably connected to and depending from each traverse, said elements each comprising a double-acting hydraulic cylinder connected to the respective traverse, a piston displaceable in said cylinder and having an outwardly projecting piston rod provided with a free end, and an enegaging portion on said free end for engaging a load; a hydraulic system for said elements, comprising a plurality of hydraulic circuits each associated with one of said elements, central control means associated with all of said circuits for operating all of said elements in unison, and individual control means each associated with one of said circuits for operating said elements individually; arresting means for arresting said cylinders in upright orientation; and extension sections connectable with said piston rods for extending the length thereof so that, at the will of an operator, said elements may be used without said extension sections for engaging a load, or be arrested in upright orientation and connected with one of said sections.

Claim 9

A crane as defined In claim 6, wherein each traverse is composed of at least two telescopable tubular sections.

Claim 10

A crane as defined in claim 7; and further comprising hydraulic cylinder and piston units in each traverse and operable for telescoping said tubular sections thereof. 9 A crane as defined in claim 1, said displacing means comprising a plurality of wheel units each having a bifurcated wheel support pivotably mounted to one of said lower end portions for vertical movement about a pivot axis, at least one wheel mounted in said wheel support, and a hydraulic cylinder and piston unit mounted in the respective upright and having a piston rod acting upon the associated wheel support for pivoting the same about said pivot axis.