Adjustable jib crane

A jib crane comprising:

• a base element mounted on a floor, said base element including an anchor embedded in the building floor, a floor plate mounted on the building floor and fixed to said anchor, an annular collar having a top rim and a bottom rim fixed to said floor plate to be coaxial with said anchor, a rotation boss seated in the annulus defined in said annular collar;
• a lower tubular mast section having a mounting flange fixed to one end thereof, and a bearing surface on said lower mast section one end receiving said rotation boss, said mounting flange having a lower surface resting on said base element annular collar top rim, said lower mast section having a plurality of fastener receiving holes defined therein, said fastener holes being spaced apart longitudinally of said lower mast section;
• an upper tubular mast section telescopingly receiving said lower section in one end thereof;
• said mast sections being longitudinally aligned and essentially upright;
• a top element connecting the other end of said upper section to a ceiling in a manner such that said upper section is freely rotatable about the longitudinal axis thereof, said top element including ceiling slope accommodating means for connecting said upright upper mast section to a ceiling which slopes with respect to said mast sections;
• connecting means connecting said mast sections together, said connecting means including a rough crane height adjustment means which comprises a tubular jacket telescopingly receiving the other end of said lower mast section and having a plurality of fastener receiving holes defined therein to be spaced apart longitudinally on said tubular jacket, and a fastener fitting through said fastener receiving holes and coupling said tubular jacekt to said lower mast section in a manner which prevents rotation of said coupled elements with respect to each other thereby further preventing rotation of said upright upper mast section with respect to said top element, and a fine crane height adjustment means which comprises a first flange on said tubular jacket, a second flange mounted on said upper mast section one end and having a plurality of bolt receiving openings defined therein, said flanges being facially opposed, a plurality of bolts mounted on said first flange and received in said second flange bolt receiving openings, said bolts preventing rotation of said upper mast element with respect to said tubular element so that said mast sections are coupled together in a non-rotatable manner by said connecting means, and a locking nut threaded onto each bolt and engaging said second flange, said flanges being separated by a distance determined according to the position of said locking nuts on said bolts so that the height of the crane is adjustable via said fine adjustment means independent of a crane height adjustment via said rough adjustment means and with said mast sections being non-rotatably connected together by said connecting means and load handling means connected to one of said most sections to move a load horizontally and vertically.