An operating mechanism for actuating a control device within a tank housing characterized by a boss extending through an aperture in the tank wall and having a bore, an operating shaft rotatably mounted within the bore and having an external handle and an internal crank portion, link means for connecting the crank portion to the control device, the bore being tapered with one end being larger than the other end, a shaft bearing within the larger end of the bore for supporting the shaft, a seal disposed within the bearing, and retainer means disposed within the bore for retaining the bearing and seal in place.