Abstract: A mechanism for opening and closing a window closure member (12) in a welder's helmut (10) by movement of the welder's chin. The helmet is provided with a chin engaging member (18), (20) which is attached to one end of an arm (24) by a rod (26). The arm (24) is pivotally connected to the helmut. As the welder lowers his chin against the chin engaging member, a roller (30) attached to the other end of pivoting arm (24) applies an opening force via rod (26) to the lower inner face of the window closure member (12) thus forcing the closure member to swing open about hinges (14). The chin engaging member is biased against the welder's chin by a spring (40). Thus an upward movement of the welder's chin will allow the window closure member (12) to return to a closed position.