56 referring again to fig2 the cam arm assembly 22 also comprises a wedge nut 60 and a cam arm 90 terminating in a cam 92 extending laterally from the cam arm 90 referring to fig8 and 9 the wedge nut 60 comprises a generally rounded wedge shaped body having a major curved face 62 and a minor curved face 64 in spaced apart juxtaposition connected by a first flat face 66 and a second flat face 68 in spaced apart juxtaposition and adapted for slidable register with the channelway 40 the major curved face 62 is provided with a plurality of parallel spaced apart raised ribs 84 extending through the wedge nut 60 intermediate the major curved face 62 and the minor curved face 64 is an aperture 72 having a generally cylindrical narrow aperture wall 74 transitioning through an annular shoulder 78 to a generally cylindrical wide aperture wall 76 to form a narrow aperture 80 coaxial with a wide aperture 82 the narrow aperture 80 is threaded the wedge nut 60 also comprises an inclined face 70 transverse to the flat faces 66 68 the wedge nut 60 is slidably received in the channelway 40 with the minor curved face 64 in slidable communication with the minor arcuate wall 44 the first flat face 66 in slidable communication with the first sidewall 50 the second flat face 68 in slidable communication with the second sidewall 52 and the ribs 84 in slidable communication with the major arcuate wall 42 referring to fig5 u2014 7 the cam arm 90 is an elongated shaft having a first end 91 and a second.