Ball valve

A valve including a valve housing with a flow axis, a valve member in said valve housing, which valve member is pivotal about a pivotal axis which is perpendicular with respect to the flow axis, a pivot shaft which is connected fixed against rotation to the valve member and is guided through a lead opening in the valve housing and is supported pivotally about the pivot axis, and a sealing system between the pivot shaft and the valve housing for sealing off the lead opening, said sealing system being designed with a base ring which is statically sealed off on the valve housing and surrounds the pivot shaft, a bellows which projects from said base ring away from the flow axis and is connected fixed against rotation and tightly to the base ring and surrounds the pivot shaft;

• a bellows end ring which surrounds the pivot shaft and is connected fixed against rotation and tightly to the bellows on its end which is remote from the flow axis, a first sliding packing ring which is attached fixed against rotation and tightly to the bellows end ring and which surrounds the pivot shaft, and a second sliding packing ring which surrounds the pivot shaft, said two sliding packing rings resting sealingly and slidingly on one another under a sealing pressure produced in part by the bellows, and the second sliding packing ring being mounted tightly and fixed against rotation on a tightly sealed cap which grips over the end of the pivot shaft, which end is the radial outer end with respect to the flow axis, said cap being screwed to the pivot shaft for an adjustable movement, the improvement wherein the cap has at its end remote from the flow axis an opening tightly sealed off by a removable cap lid, a releasable locking means is stored inside of the cap and is releasable when the cap lid is released for allowing a biasing pressure of the bellows to be selectively adjusted by rotating the cap on the screwed pivot shaft prior to the securing of the cap lid and the locking means, said locking means securing the cap against rotational screwed movement relative to the pivot shaft, and working surfaces for engagement by a tool are provided on the cap or on the cap lid, thereby permitting the pivot shaft to be pivoted for moving the valve member, while preventing any axial movement of the sealing system and maintaining the preselected bellows biasing pressure.