Birch, Stewart, Kolasch & Birch
Portable, assemblable-disassemblable staircase
 A portable, assemblable-disassemblable staircase includes a plurality of stair units to be assembled and disassembled, each of the stair units including a horizontal base plate, an upward joint vertically installed at a rear end of the horizontal base plate, the upward joint containing a longitudinal elongated hole bored therein, a downward joint vertically installed at a front end of the horizontal base plate, a nut fixedly installed in the downward joint, a bolt adapted to be spirally inserted into the nut through the longitudinal elongated hole of the upward joint so as to inserting and fixing the downward joint of one stair unit into and to the upward joint of the other stair unit of the plurality of stair units, and a tread to be fixed to the upper surface of the horizontal base plate, whereby the stair units are assembled by alternatively mating with the downward joint and upward joint so that horizontal sections of the downward and upward joints can be prevented from circularizing to be unrotatable. 
E
E04F
inventional
Keiichiro
Yamazaki