Image Number 3 for United States Patent #4236769.
A display stand is provided with a plurality of ring-like shelves arranged in a vertical array above a base with the first, third, fifth, etc., shelves above the base being in a first group which are rotatable in a first direction and with the second, fourth, sixth, etc., shelves above the base being in a second group which are rotatable in a second, opposite direction. A plurality of rotatable drive rods are spaced equidistantly around a circle in the base and project upwardly therefrom within the interior of the ring-like shelves. Each drive rod carries fixed rollers which rotate with the drive rod and which each have an annular groove therein for supporting and frictionally engaging an inner portion of one of the ring-like shelves. One half of the drive rods are thus engaged with the first group of shelves and are driven by a motor to rotate in the first direction. The other half of the drive rods are thus engaged with the first group of shelves and are driven to rotate in the second, opposite direction. When a predetermined amount of resistance torque is applied to one of the shelves upon removal of an article from that shelf, the frictional driving torque is overcome and that shelf remains stationary while the rollers engaged with that shelf slip relative to the shelf and continue to rotate.