but non circular shape the threaded shaft 40 shown in fig9 11 includes a central shaft 80 on a common axis and disposed through the first portion 41 of the threaded shaft 40 and the second portion 42 of the threaded shaft 40 in the illustrated embodiment the first portion 41 and the second portion 42 of the threaded shaft 40 are separate pieces the central shaft 80 includes a central shaft receiver for accepting a rotational tool used to turn the central shaft 80 in the embodiment shown the first receiver 71 and internal receiver 72 serve as central shaft receivers for the central shaft 80 in some embodiments the central shaft receiver may extend outside of the coupling of the threaded shaft 40 with the frame 36 to allow particular rotation capabilities or other operation of the central shaft beyond the frame 36 for the embodiment of fig9 11 the central shaft 80 may be translated along the common axis relative to the first portion 41 and the second portion 42 of the threaded shaft 40 fig9 and 10 show the central shaft 80 in a first position and fig1 shows the central shaft in a second position relative to the first portion 41 and the second portion 42 of the threaded shaft 40 in the first position central shaft 80 is rotationally engaged with both the first portion 41 and the second portion 42 of the threaded shaft 40 in the second position central shaft 80 is rotationally engaged with the first portion 41 of the.