Abstract: The valve disk of a butterfly valve is carried by a valve shaft, which is mounted in bearing bushings, which are fitted in the valve body. Each bearing bushing is formed in its outside peripheral surface with two peripheral grooves and between said grooves with diametrically opposite grooves for receiving sealing rings and axial sealing strips, respectively. The inner peripheral groove is disposed adjacent to the valve body. The outer peripheral groove is adjacent to the hub of the valve disk. Said hub surrounds the adjacent bearing bushing at its end protruding into the interior of the valve body. The two axial grooves register with the valve disk when the same is closed. To ensure a long life and a permanently tight seal, the outer peripheral groove contains two superimposed sealing rings. The upper one of said superimposed sealing rings consists of a polytetrafluoroethylene strip, which is narrower than the peripheral groove and has free ends which abut and define an oblique joint.

Abstract: A valve housing has a circular cylindrical tubular member and a tubular body having a central portion which is substantially rectangular in cross-section and has mutually opposite, first and second side walls. The first side wall has in cross-section a length equal to the diameter of said tubular member, which is joined to said first side wall and extends at right angles thereto. A motor-operable valve member is axially slidably mounted in said tubular member and comprises a laterally open shell, which consists of a part of a circular cylinder and is coaxial to said tubular member and substantially defined by that cross-sectional plane of said central portion which includes the axis of said tubular member, a circular ring at the end remote from said second side wall, and an end wall at the end opposite to said circular ring.