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US 2002/0170871 A1Published application
Jib crane
AssigneeIshi Kawajima-Harima Jukogyo Kabushiki Kaisha
InventorIsao Miyazawa
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AssigneeIshi Kawajima-Harima Jukogyo Kabushiki Kaisha
InventorIsao Miyazawa
Estimating the term…
A jib is supported for its luffing movement by a luffing rope mounted to a longitudinally intermediate portion of the jib. The jib has a truss structure with upper and lower beam members respectively overhanging upward and downward of load action line which connects a lifting point with a support pin. Assuming that, when the burden of maximum load is lifted up, P is a load applied on the load action line from the tip of the jib; H is a width between upper and lower portions of the jib at a mounting point of the luffing rope; Eu and El are overhang eccentric lengths of the upper and lower beam members at the mounting point of the luffing rope with respect to the load action line, respectively; and Au and Al are cross-sectional areas of the upper and lower beam members, respectively, then cross-sectional areas Au and Al of the upper and lower beam members are determined depending upon overhang eccentric lengths Eu and El of the upper and lower beam members to satisfy 1 P × El H · Au > P × Eu H · Al , so that an upper portion of the jib is recurved toward a crane body when the burden of maximum load is lifted up.
A jib crane characterized in that a jib mounted to a crane body is supported for luffing movement thereof by a luffing rope mounted to a longitudinally intermediate portion of the jib, the jib having a truss structure with upper and lower beam members respectively overhanging upward and downward of load action line which connects a lifting point with a support pin, cross-sectional areas Au and Al of the upper and lower beam members, respectively, being determined depending upon overhang eccentric lengths Eu and El of the upper and lower beam members, respectively, so as to satisfy
A jib crane characterized in that a jib is mounted for a luffing motion thereof on a crane body, an A-frame, which guides a lifting rope to a lifting point on the jib, comprising rear and front frames, the rear frame having a sheave for the lifting rope at an upper end thereof and being pivoted at a lower end thereof to a revolving frame, the front frame being pivoted at an upper end thereof to a portion of said rear frame backward of the sheave and being pivoted at a lower end thereof to the revolving frame, cross-sectional areas Af and Ab of the front and rear frames, respectively, being set to satisfy
Dependencies are inferred from the claim text.