Boom rigging

Claim 1

A boom rigging, comprising: a. a swivel support having a central opening therein with a bearinG surface surrounding the same and a pair of hook support members at the extremities of the same; b. a support cable positioned through the central opening in the swivel support and adapted to be secured taut at the top and bottom of the tank in which the boom rigging is to be placed; c. a bearing lock means adjustably positioned on the support cable and near one extremity of the same and supporting the swivel support on the cable for rotational movement; d. a trolley member positioned on the support cable and having roller guide means positioned around the cable to guide the trolley member on the support cable, said trolley member having flanges on opposite sides of the same intermediate the roller guide means, said trolley member including an enclosed sheave with pulley wheels at the open extremities of the same and aligned guide pins spaced intermediate the pulley members and from a line of the axes of the pulley wheels to define a path substantially equal in width to the diametrical dimension of the support cable; e. a boom pivotally mounted on one of the flanges of the trolley member and including a pivotally mounted chair support positioned at the extremity of the same, said pulley wheels at the ends of the trolley member being spaced apart a distance which bears the ratio with the length of the boom of no greater than 1-7; f. means connected between the other of the flanges on the trolley member and one of the pair of hook support members on the swivel support and disposed to one side of the support cable extending parallel thereto for moving the trolley member on the support cable; and g. means connected between the other of the hook support members on the swivel member and the unpivoted extremity of the boom adjacent the chair support and operated from the chair support for pivoting the boom on the trolley member.