A locking and unlocking device for a manually movable wheeled storage rack or the like is disclosed wherein a toothed locking wheel is operatively connected to wheels of a storage rack, and a pair of locking and unlocking leverages each including a catch are disposed symmetrically about the axis of the locking wheel so that the catches may selectively engage with or disengage from the teeth of the locking wheel by the operation of operating knobs exterior of the storage rack. When one of the catches is made into engagement with the toothed locking wheel while the other is out of engagement therefrom, the rotation in one direction of the locking wheel is locked while the rotation in the other direction is unlocked, and vice versa.