GB695385A - Improvements in or relating to plug valves and actuators therefor - Google Patents

Abstract

695,385. Valves. CAMERON IRON WORKS, Inc. Nov. 15, 1950 [Dec. 3, 1949; Dec. 30, 1949], No. 27921/50. Class 135 A tapered plug valve comprises a plug member 15, Fig. 1, engaging a liner 11 in a housing 6 and supported by stems 16, 16a, the stem 16 being connected by a yoke 25, Fig. 4, to a crank 23 on a shaft 21, whereby rotation of the shaft through 180 degrees causes slight axial movement to ease the plug 15 from the liner, then rotary movement of the plug through 90 degrees, and finally an axial movement of the plug 15 to jam it in the liner. The rotational axes of the stem, the shaft 21 and the yoke tongue 24 all meet at a common point 26a, but the rotational axis of the yoke on the stem is eccentric of this point to cause the said axial movements. In another arrangement, the stem 122, Fig. 6, carries a member 136 having a horizontal slot 141 extending into a vertical slot 145, Fig. 10, and a recess 145a. The actuating shaft 129 has an eccentric pin 138 engaging the slot 141 and an angular crank 142 engageable with the slot 145. To move the plug member 116 from, say, open to closed position, the shaft is rotated through 270 degrees. During the first 45 degrees, pin 138 causes freeing of the member 116 while crank 142 moves in recess 145a and does not rotate the member. For the next 180 degrees, crank 142 engages slot 145 and turns the plug through 90 degrees and during the final 45 degrees, the crank 142 moves in the recess 145a while the pin 138 causes jamming of the plug member against the liner.