Abstract: A new, unique combination of the tractrix valve and the tractrix stem seal is described as an improvement over the original patents issued. The plug and the stem seal are juxtaposed large end to large end. The stem seal functions as a fluid seal and as a journal bearing. The purpose of the tractrix valve is to prevent leaks through the seat of the valve and to the outside environment past the stem seal by use of long-term self-renewing tractrix surfaces that continue to mate after continued use.

Abstract: The preferred embodiment comprising a truncated cone valve plug, or a truncated cone with curved sides as in the tractrix valve is described. A step is fabricated into the large end of the valve plug. A secondary seal, called a Veri-Seal, is placed on the large end of the valve plug on the step at an intermediate location between the outer diameter of the plug and the stem. Pressure forces acting downward on the step on the top of the valve plug balance the pressure forces acting upward in the channel through the valve plug. By placing the Veri-Seal at this intermediate location on the top of the plug, the spring force can be minimized and the resulting torque to open and close the valve is consequently reduced.

Abstract: A new, unique combination of the Tractrix Valve and the Tractrix Stem Seal is described as an improvement over the original patents issued. The plug and the stem seal are juxtaposed large end to large end. The stem seal functions as a fluid seal and as a journal bearing. The purpose of the Tractrix Valve is to prevent leaks through the seat of the valve and to the outside environment past the stem seal by use of long-term self-renewing tractrix surfaces that continue to mate after continued use.

Abstract: A retrofit valve stem seal assembly, which can be retrofitted to existing quarter-turn valves already in service, is provided. The retrofit valve stem seal assembly is added to the valve stem by inserting a valve stem adaptor onto the valve stem and firmly attaching the adaptor to the valve stem. The inner surface of the valve stem adaptor fits on the valve stem. To prevent leaks between the valve stem adaptor and the valve stem, "O" rings are installed in the valve stem adaptor to bear against the valve stem. A rotatable valve stem adaptor includes a sliding tractrix surface for sliding contact with a stem packing. The stem packing includes a complementary tractrix surface for contacting the sliding tractrix surface on the valve stem. Wear between the contacting surfaces is uniform at all points of contact between the sliding tractrix surface and the complementary tractrix surface, creating and maintaining a dynamic seal.

Abstract: A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem.The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet.

Abstract: An improved plug valve wherein a novel shape for the valve plug and valve chamber provide mating surfaces for improved wear characteristics. The novel shape of the valve plug is a frustum of a body of revolution of a curved known as a tractrix, a solid shape otherwise known as a peudosphere.