and is located between member 42 39 and bearing 58 shaft 10 can also be dismounted by pulling on knob 59 to the right in fig3 to disengage drive stud 42 39 from the inside of base member 17 and thereafter pivoting shaft 10 about drive stud 42 shaft 10 can be mounted into the position of fig3 by reversing the steps described above for dismounting it after expandable shaft 10 has been dismounted from machine 13 valve member 35 is actuated to permit the compressed air to flow from bladder 30 whereupon the clearance is again realized between the inside of core 14 and the expandable shaft 10 so that the core 14 can be slid off of shaft 10 in fig9 an alternate embodiment of the expandible shaft is shown in cross section within a core 14 39 the tubular member 17 39 is of the cross sectional configuration shown wherein the ends of sides 19 39 20 39 21 39 and 22 39 are extended in both directions to provide the extensions 19a 20a 21a and 22a respectively which serve the same functions as the channel members 23 24 and 25 the outer corners of the extensions 19a 20a 21a and 22a lie on a circumference having a diameter which is approximately 1 16 34 less than the internal diameter 29 39 of core 14 39 and when bladder 30 39 is inflated it will pull the core into contact with the outer end corners of extensions 20a and 22a and the corners of extensions 19a and 21a extending outwardly from side 20 39 but there will be a clearance at the corners of extensions 22a and the.