Variable speed drive for a potter{3 s wheel

Claim 1

In a potter''s wheel having a generally vertical drive shaft, a rotatable turn table at the upper end of said drive shaft, bearing means supporting the shaft for rotation, an improved variable speed friction drive mechanism comprising: a drive disc connected to the shaft below said turn table, an electric motor including an output shaft, a drive cone secured to said output shaft, said drive cone having a base portion of a relatively large diameter and reducing in diameter from said base outwardly to a tip at a rate resulting in the drive surface of the drive cone being of circular curvature axially of the drive cone, with the drive surface of the drive cone being contactable with a lower peripheral portion of the drive disc, means mounting said motor for pivotal movement about a horizontal axis which extends transversely of the output shaft axis, said axis being located radially outwardly from the axis of rotation of the vertical drive shaft and below the drive disc, between the drive motor and the drive disc, and substantially at the center of axial curvature of the drive cone, so that the weight of the drive motor tends to rotate the drive cone in a direction placing the tip of said drive cone contiguous the periphery of the drive disc, and control lever means for pivoting the motor about said generally horizontal axis, for moving the drive cone axially, so as to change the diameter of a circle of contact of the drive cone with the drive disc, to in that manner change the drive speed of the drive disc by the drive cone, and wherein the drive cone is made from a relatively hard material and the drive disc comprises a flexible peripheral portion which is deflected some when it is in contact with the drive cone, said flexible peripheral portion having sufficient stiffness so that when deflected it is self-biased into friction contact with the drive cone.