Valve with active seal and shaft blowout prevention device

A valve comprising:

• a valve body defining a shaft bore therethrough, the shaft bore defining an axis extending through the valve body;
• a valve shaft positioned within and configured to rotate within the shaft bore of the valve body, the valve shaft comprising a first section and a second section, the first section proximate to a top end of the valve shaft and defining a minor shaft diameter and the second section distal from the top end of the valve shaft and defining a major shaft diameter, the major shaft diameter of the valve shaft being greater than the minor shaft diameter of the valve shaft, the valve shaft comprising a shaft shoulder defining a shaft shoulder surface facing upward, the shaft shoulder positioned at an intersection between the first section and the second section of the valve shaft, the shaft shoulder surface extending from the first section to the second section;
• a top cap secured to the valve body, the top cap defining an upper surface and a lower surface distal from the upper surface, the top cap further defining a bore extending from the upper surface to the lower surface, the bore defining a major bore and a minor bore, each of the major bore and the minor bore being cylindrical, the major bore intersecting the lower surface and defining a major bore diameter, the minor bore intersecting the upper surface and defining a minor bore diameter, the major bore diameter being greater than the minor bore diameter, the top cap comprising a bore shoulder extending from the minor bore to the major bore and defining a bore shoulder surface facing downward, the bore shoulder surface facing the shaft shoulder surface, the major shaft diameter of the valve shaft greater than the minor bore diameter of the minor bore of the top cap but less than the major bore diameter of the major bore of the top cap, movement of the second section of the valve shaft through the minor bore of the top cap stopped by the shaft shoulder surface;
• and
• a seal positioned between the top cap and the valve body, the seal configured to seal against leakage from between the valve body and the valve shaft.