Abstract: A dumbbell with a weight adjusting mechanism, which utilizes an electric motor, a rack and pinion gear linkage driven by the motor, and photoelectric position detection assemblies, to control the movement of two racks inside the handle bar of the dumbbell. The two racks move simultaneously in opposite directions by the same distance in a precisely controlled manner based on position signals provided by the position detection assemblies. The racks extend and retract within a center channel formed by center openings of a plurality of aligned and axially engaged weight plates, so that a desired number of the weight plates will be lifted by the dumbbell handle. A control system controls the motor and communicates with a user via a user interface panel on the handle bar or an external handheld device wireless connected to the control system.

Abstract: A dumbbell with a weight adjusting mechanism, which utilizes an electric motor, a rack and pinion gear linkage driven by the motor, and photoelectric position detection assemblies, to control the movement of two racks inside the handle bar of the dumbbell. The two racks move simultaneously in opposite directions by the same distance in a precisely controlled manner based on position signals provided by the position detection assemblies. The racks extend and retract within a center channel formed by center openings of a plurality of aligned and axially engaged weight plates, so that a desired number of the weight plates will be lifted by the dumbbell handle. A control system controls the motor and communicates with a user via a user interface panel on the handle bar or an external handheld device wireless connected to the control system.