Abstract: Disclosed is a dumbbell of the type commonly found in a fitness center to be used as a weight training device during a weight training or exercise program. The dumbbell includes a gripping handle and a pair of collars fixedly connected to opposites ends of the handle. A series of weight plates having correspondingly different weights are adapted to be detachably connected to each other and to each one of the collars so as to enable a user to selectively and incrementally adjust the gross weight of the dumbbell to conform to his weight training program. Each weight plate carries a lock cartridge having an engagement pin moving therethrough between retracted and extended positions in response to a manual pushing force. In the extended position, the engagement pin of an additional weight plate is received within an engagement pin extension channel of an existing weight plate being carried by the dumbbell, whereby to prevent a disconnection of the additional weight plate from the existing weight plate.

Abstract: A weight plate for use with physical fitness equipment comprising a plate body with at least a main throughbore and, possibly, other throughbores passing therethrough. The body additionally has an internal bore within the thickness of the plate body which intersects the main central throughbore. A spring loaded selector pin is movably mounted within the internal bore to selectively engage and disengage the plate body to a post positioned in the main throughbore. A handle is mounted to the selector pin externally to the plate to selectively position the selector pin.

Abstract: A weight plate for use with physical fitness equipment is disclosed including a plate body with a central and two outwardly throughbores. The body additionally has an internal bore within the thickness of the plate body which intersects the central throughbore. A selector pin is movably mounted within the internal bore to selectively engage the plate body to a center post. A toggle lever is mounted in the plate to selectively position the selector pin.