Abstract: The present invention is a unique semi-automatic mop wringer. The mop wringer comprises a hollow housing vertically movably supported on a supporting structure by a suspension mechanism. The housing is engaged with the supporting structure through a rack-and-gear mechanism, so that a downward motion of the housing can be transmitted into the rotation of crank members which in turn drive a wringer roller to squeeze the mop against a wringer plate mounted inside the housing. A user can use the present invention mop wringer to wring a mop by placing the mop inside the housing, holding the mop holder and applying a downward force. The downward motion of the housing causes the wringer roller to move in a circular path to squeeze the mop against the wringer plate. When the user withdraws the downward force, the housing moves back upwardly to allow the user to repeat the process.

Abstract: The present invention is an improved quick release locking nut for quick change type mop holders. The mop holder has a frame attachable to a mop stick and a clamping member for securing mop fill. The quick release locking nut is slidably mounted on a central shank of the frame, and has a pivotally mounted pawl which is biased by a spring. The inner screw threads on the tip of the pawl are engaged with the outer screw threads on the central shank, in order to lock the quick release locking nut on the central shank for preventing the clamping member from sliding on the central shank. When the pawl is pressed against the spring and its tip is disengaged from the central shank, the quick release locking nut is unlocked and can be slid on the central shank for allowing the clamping member to slide on the central shank so that the mop clamp can be released.