A clutch assembly for a roller door operator, the clutch assembly providing selective engagement with a drive wheel, the clutch assembly comprising: a rotatable shaft rotatable relative to the drive wheel; a clutch disc supported in a clutch lever and arranged to rotate with the rotatable shaft, the clutch disc and clutch lever configured to rotate relative to one another around the axis of rotation of the shaft; and a clutch cam supported in a clutch base, the clutch base configured to permit operative rotation of the clutch cam around the axis of rotation of the shaft in a first direction; wherein the clutch lever is operatively associated with the clutch cam so that rotational movement of the clutch lever in a second direction opposite to the first direction actuates movement of the clutch disc and the clutch lever axially along the rotatable shaft to engage or disengage the clutch disc with the drive wheel, and subsequent rotational movement of the clutch lever in the first direction actuates rotational movement of the clutch cam relative to the clutch base in the first direction.