A tapered rotary valve plug fits into a tapered valve chamber and is rotated by an operating head or cap. Cam means are provided to automatically shift the operating head and valve plug axially as the head is rotated.Plug Valves A pin-and-slot connection between the operating head and valve plug is provided whereby rotation of the plug is delayed until the plug has been lifted from its seat, after which rotation of the plug takes place as rotation of the head is continued.Safety valves Spring means, tensioned during the initial relative rotation of the operating head and plug, are provided for restoring head and plug to their original position relative to each other as soon as the valve plug has been loosened from its seat. Means are also provided for positively stopping rotation of the plug at full open or closed positions. A rotary plug valve comprising a tapered valve plug,BUTTERFLY VALVES valve plug operating means including a rotary and axially movable plug operating head, a valve casing including a tapered valve chamber for receiving said tapered valve plug, said valve chamber having inlet and outlet ports communicating therewith and a first cylindrical extension for receiving said rotary and axially movable plug operating head therein, cam means responsive to rotation of the operating head for imparting axial movement to the head when the head is rotated, said tapered rotary valve plug fitting within said tapered valve chamber and being provided with a transverse for communicating with the inlet and outlet ports when the valve is in open position, first means interconnecting the operating head and valve plug to provide an immediate lifting operation to the plug when the head is rotated to loosen the plug from its seat, said interconnecting means also serving to provide delayed rotation of the plug after initial rotation of the head until the plug has been raised from its seat, and additional interconnecting means comprising a spring pin interposed between the operating head and valve plug for restoring the head and plug to their initial position relative to each other after the plug has been raised from its seat.

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