axis 39 s position in fig1 as wheel 40a wears down to the diameter of wheel 40 the tangential lines of contact will be shifted from lines 30a and 32a towards lines 30 and 32 and axis 38 and the wheel will be shifted clockwise and down toward pillow block 12 posts 34 and 36 accomplish the aforementioned shifting of the wheel and axis 38 as described in connection with the fig5 detail view of post 36 post 36 has a round shank 74 that closely and translatably fits in a blind bore 76 and rotates therein both the bore and the shank being oblique to the upper surface of pillow block 12 at the upper end of shank 74 is yoke 78 to which clamp 80 is fastened by bolts 82 and 84 so as to form an eye in which spindle shaft 38 is journalled when posts 34 and 36 rise they turn spindle shaft 38 slightly clockwise as seen in fig1 and 1a while raising spindle shaft 38 away from the upper surface of pillow block 12 the posts swivel slightly in bores 76 as spindle shaft 38 turns so that the eyes remain coaxial with the spindle shaft and do not bind it posts 34 and 36 have a means for releasably locking in a selected position this means including an open collet 86 shown in fig4 and 5 at the base of collet 86.