Patent ID: 7938762

Claim:
An automatic weight stack controller for fitness equipment, comprising: a frame having a base, upright columns, and an upper top; a cable for raising a stack of weights or a selected part thereof disposed in the frame, wherein said stack of weights are comprised of plates guided by the columns; a vertical hole disposed in each weight of the stack of weights; a “V” section or partially circular groove defined within the vertical hole of each weight of the stack of weights; a vertical tube having radial holes level with each one of the grooves, wherein a plurality of balls are disposed in the radial holes; a threaded rod disposed within the vertical tube and attached to an axle of an electric engine; and a piston having a cylindrical shape and conical ends attached to the threaded rod; wherein an external diameter of the piston is less than an inner diameter of the vertical tube; wherein a wall thickness of said vertical tube is less than the diameter of the balls, such that the balls that are level with the piston fit into the groove of a weight of the stack of weights that is level with the piston; and wherein the vertical tube is attached to the cable.