| 251 / | HD | VALVES AND VALVE ACTUATION |
| 157 | DF | WITH MEANS TO INCREASE HEAD AND SEAT CONTACT PRESSURE {8} |
| 158 | DF | .~ With positive reduction {3} |
| 160 | DF | .~.~ Rotary valve {3} |
| 164 | DF | .~.~.~ Screw {1} |
| 165 | | .~.~.~.~ Non-reciprocating {1} |
| 166 | DF | .~.~.~.~.~> With slip coupling |