A friction clutch assembly connects driving and driven shafts and has a pressure plate axially moveable between an engaged position transmitting torque from the driving shaft to the driven shaft and a disengaged position. The remote venting configuration provides the expansion bladder with access to atmospheric pressure existing about the x-ray tube so as to enable it to compensate for pressure changes within the liquid-filled container that occur as a result of liquid heating. The glass substrate includes an anti-reflective coating on the surface that is closer to the at least one light source, and the glass substrate is textured on the surface opposite the AR-coated surface. R1 represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. At least one restrictor element is located in the passage to dampen sound of the unit.