Mechanism, assembly and sheet material dispenser for manually actuating rotation of a roller

A mechanism is provided for manually actuating rotation of a roller of a sheet material dispenser for dispensing a predetermined length of sheet material. The mechanism includes a frame member; a driven member configured for coupling with the roller; an actuating member configured to rotate about a rotation axis in a first direction through manual actuation by a user; and a driver member coupled with the actuating member. The rotation axis is movably mounted on the frame member to be movable between a first position allowing rotation of the roller caused by rotation of the actuating member in the first direction, and a second position preventing rotation of the roller caused by rotation of the actuating member in the first direction. The mechanism includes a first urging member configured to urge the rotation axis in the first position. A related assembly and dispenser including the mechanism are also provided.