Level luffing crane

Claim 2

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said second assembly defining a second effective lever arm with respect to the pivotal mounting of the outer boom, said booms being movable in a traverse from an extended position in which the inner boom inclines upward on one side of the vertical and the outer boom extends further to the same side thereof and the angle between the booms being less than 180 degrees, to a retracted position in which the inner boom inclines upward on the other side of the vertical and the outer boom extends to the first mentioned side thereof, the positions of the booms, hydraulic cylinder assemblies, and pivotal connections being such that

Claim 3

The device set forth in claim 1 in which l2 l1.

Claim 4

The device set forth in claim 1 in which the means interconnecting the hydraulic cylinder assemblies is such that as one retracts the other extends, and vice versa.

Claim 5

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an oUter boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said assembly defining a second effective lever arm with respect to the pivotal mounting of the outer boom, said booms being movable in a traverse from an extended position in which the inner boom inclines upward on one side of the vertical and the outer boom extends further to the same side thereof and the angle between the booms being less than 180*, to a retracted position in which the inner boom inclines upward on the other side of the vertical and the outer boom extends to the first mentioned side thereof, the ratio of the effective lever arm of the second hydraulic cylinder assembly to the effective lever arm of the first hydraulic cylinder assembly increasing as the booms move along the traverse away from extended position toward retracted position, and means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action so that one retracts as the other extends, and vice versa, to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 6

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an oUter boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said assembly defining a second effective lever arm with respect to the pivotal mounting of the outer boom, said booms being movable in a traverse from an extended position in which the inner boom inclines upward on one side of the vertical and the outer boom extends further to the same side thereof and the angle between the booms being less than 180*, to a retracted position in which the inner boom inclines upward on the other side of the vertical and the outer boom extends to the first mentioned side thereof, the ratio of the effective lever arm of the second hydraulic cylinder assembly to the effective lever arm of the first hydraulic cylinder assembly increasing as the booms move along the traverse away from extended position toward retracted position, and means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action so that one retracts as the other extends, and vice versa, to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 7

The combination set forth in claim 4 in which the hydraulic cylinder assemblies are proportioned so that they require the same volume of hydraulic fluid to complete their full strokes, respectively.

Claim 8

The combination set forth in claim 4 in which each hydraulic cylinder assembly has a piston end, and wherein said hydraulic means includes a valve-controlled passage connecting the piston ends of both hydraulic cylinder assemblies, for transfer of hydraulic fluid from one to the other.

Claim 9

The combination set forth in claim 4 in which an extension boom is telescopically mounted on said outer boom, and sheave means at one end of said extension boom.

Claim 10

The combination set forth in claim 7 in which full retraction of the second hydraulic cylinder assembly serves to swing the outer boom to a folded position under the inner boom.

Claim 11

The combination set forth in claim 4 in which P1V1 Congruent P2V2 where P1 unit pressure in first hydraulic cylinder assembly at a given instant; P2 unit pressure in second hydraulic cylinder assembly at the same instant; V1 displacement volume of the first hydraulic cylinder assembly during said traverse; V2 displacement volume of the second hydraulic cylinder assembly during said traverse.

Claim 12

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said booms being movable between an extended position and a retracted position, in extended position the inner boom including upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, the effective lever arm of the first hydraulic cylinder assembly remaining substantially constant, and the effective lever arm of the second hydraulic cylinder assembly increasing as the booms move away from extended position toward retracted position, and hydraulic means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 13

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said booms being movable between an extended position and a retracted position, in extended position the inner boom including upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, the effective lever arm of the first hydraulic cylinder assembly remaining substantially constant, and the effective lever arm of the second hydraulic cylinder assembly increasing as the booms move away from extended position toward retracted position, and hydraulic means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 14

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said second assembly defining a second effective lever arm with respect to the pivotal mounting of the outer boom, said booms being movable between an extended position and a retracted position, in extended position the inner boom inclining upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, the effective lever arm of the second hydraulic cylinder assembly remaining substantially constant, and the effective lever arm of the first hydraulic cylinder assembly decreasing as the booms move away from extended position toward retracted position, and hydraulic means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 15

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said second assembly defining a second effective lever arm with respect to the pivotal mounting of the outer boom, said booms being movable between an extended position and a retracted position, in extended position the inner boom inclining upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, the effective lever arm of the second hydraulic cylinder assembly remaining substantially constant, and the effective lever arm of the first hydraulic cylinder assembly decreasing as the booms move away from extended position toward retracted position, and hydraulic means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 16

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said booms being movable between an extended position and a retracted position, in extended position the inner boom inclining upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, the effective lever arm of the second hydraulic cylinder assembly progressively increasing, and the effective lever arm of the first hydraulic cylinder assembly progressively decreasing as the booms move away from extended position toward retracted position, and hydraulic means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 17

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said booms being movable between an extended position and a retracted position, in extended position the inner boom inclining upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, the effective lever arm of the second hydraulic cylinder assembly progressively increasing, and the effective lever arm of the first hydraulic cylinder assembly progressively decreasing as the booms move away from extended position toward retracted position, and hydraulic means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 18

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said second assembly defining a second effective leveR arm with respect to the pivotal mounting of the outer boom, said booms being movable in a traverse between an extended position and a retracted position, in extended position the inner boom inclining upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, and the angle between the booms being less than at extended position, the ratio of the effective lever arm of the second hydraulic cylinder assembly to the effective lever arm of the first hydraulic cylinder assembly increasing as the booms move away from extended position toward retracted position, whereby substantially equal pressures are induced in said hydraulic cylinder assemblies at each point along said traverse, and means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 19

An articulated crane, comprising in combination: a base member, an inner boom, pivot means mounting said inner boom on the base member, an outer boom pivotally mounted on the inner boom, means including a first extensible hydraulic cylinder assembly for independently swinging said inner boom with respect to said base member in an arc on both sides of the vertical position, said assembly defining a first effective lever arm with respect to said pivot means, means including a second extensible hydraulic cylinder assembly for independently swinging said outer boom with respect to said inner boom, said second assembly defining a second effective leveR arm with respect to the pivotal mounting of the outer boom, said booms being movable in a traverse between an extended position and a retracted position, in extended position the inner boom inclining upward on one side of the vertical and the outer boom extending further to the same side thereof, and the angle between the booms being less than 180*, in retracted position the inner boom inclining upward on the other side of the vertical and the outer boom extending to the first mentioned side thereof, and the angle between the booms being less than at extended position, the ratio of the effective lever arm of the second hydraulic cylinder assembly to the effective lever arm of the first hydraulic cylinder assembly increasing as the booms move away from extended position toward retracted position, whereby substantially equal pressures are induced in said hydraulic cylinder assemblies at each point along said traverse, and means interconnecting said hydraulic cylinder assemblies to coordinate their simultaneous action to cause the outer end of the outer boom to move substantially horizontally and above the level of said pivot means.

Claim 20

The combination set forth in claim 13 in which the hydraulic cylinder assemblies displace different volumes of fluid in their respective strokes between extended position and retracted position.

Claim 21

The combination set forth in claim 14 in which two positive displacement pumps are provided, one connected to each hydraulic cylinder assembly, respectively, the pumps being mechanically connected for dependent rotation.