Multiple stage extensible boom

Abstract

An extensible boom for portable lights has a two-part base. One part of the base is fixed to a trailer or other vehicle and the other part is rotatable with respect thereto about a vertical axis. Hinged to the rotatable part about a horizontal axis is a telescopic multisection boom. A first winch elevates the boom from horizontal to vertical position. A second winch controls a cable system located inside the boom sections to elevate the boom. A manually extensible top boom section may be used to increase the maximum height.

What we claimed is: 
     
       1. An extensible boom for portable lights comprising a vehicle, a first base section mounted on said vehicle .Badd.and supported by said vehicle above the ground.Baddend., a second base section, means mounting said base sections together for rotation of said second base section relative to said first base section about a vertical axis through substantially 360°, a hollow first boom section, means mounting said first boom section on said second base section for pivotal movement between a horizontal collapsed position and a vertical erect position, first winch means on said second base section for moving said first boom section between collapsed and erect positions, a second boom section telescopically movable within said first boom section between retracted and extended positions, second winch means on said first boom section for moving said second boom section between retracted and extended positions, and lights mounted on the outer end of the outermost of said boom sections .Badd., each said boom section being formed of substantially imperforate solid tubing, said second winch being provided with a cable, said cable reeved extending from said second winch up inside said first boom section around a pulley fixed to the inside of the outer end of said first boom section and thence back to an anchor on the lower end of said second boom section, whereby said pulley and substantially all of said cables are contained within said boom sections.Baddend.. .Badd..[..[.2. An extensible boom according to claim 1 in which said second winch is provided with a cable, said cable reeved extending from said second winch up inside said first boom section around a pulley fixed to the inside of the outer end of said first boom section and thence back to an anchor on the lower end of 
     
     
        said second boom section..]..]..Baddend. 3. An extensible boom according to claim .Badd..[..[.2.]..]..Baddend. 1 which further comprises a third boom section telescopically movable within said second boom section, a second cable fixed to said first boom section, a second pulley fixed to the inside of the outer end of said second boom section, said second cable running around said second pulley and thence back to a second anchor on the lower end of said third boom section .Badd., said second cable and said second pulley being contained within said second and third boom sections.Baddend.. 4. An extensible boom according to claim 3 which further comprises a fourth boom section on which said lights are mounted, said fourth boom section being telescopically movable in said third boom section and manually movable between retracted and extended positions, latch means securing said fourth boom relative to said third boom, and each of said boom sections having noncircular tubular members which are nonrotatable relative to each other. .Iadd. 5. An extensible boom for portable lights comprising a base, a hollow .Badd.substantially imperforate, solid tubing .Baddend.first boom section mounted on said base, a hollow .Badd.substantially imperforate, solid tubing .Baddend.second boom section telescopically movable with said first boom section.Iadd..[..[.,.]..]..Iaddend.  between retracted and extended positions, a .Badd.hollow substantially imperforate, solid tubing .Baddend.third boom section telescopically movable within said second boom section, winch means on said first boom section, a first cable reeved extending from said winch means up inside said first boom section around a first pulley fixed to the inside of the outer end of said first boom section and thence back to a first anchor on the lower end of said second boom section, a second cable fixed to said first boom section, a second pulley fixed to the inside of the outer end of said second boom section, said second cable running around said second pulley and then back to a second anchor on the lower end of said third boom section, whereby .Iadd..[..[.on.]..]..Iaddend.  operating said winch means .Iadd..[..[.,.]..]..Iaddend.  in one direction with said sections collapsed causes said first cable to pull said first anchor toward the upper end of said first section thereby elevating said second section and simultaneously causing said second cable to be extended and to move said third section toward the upper end of said second section, and lights mounted on the outer end of the outermost of said boom sections .Badd., all of said pulleys and all of said second cables and substantially all of said first cable being contained within said boom sections.Baddend.. .Iadd. 6. A boom according to claim 5 which further comprises a fourth boom section telescopically movable in said third boom section and manually movable between retracted and extended positions. .Iaddend.