| 307 / | HD | ELECTRICAL TRANSMISSION OR INTERCONNECTION SYSTEMS |
| 112 | DF | SWITCHING SYSTEMS {5} |
| 116 | DF | .~ Condition responsive {4} |
| 119 | DF | .~.~ Mechanical force {1} |
| 120 | DF | .~.~.~ Speed, centrifugal or kinetic force {4} |
| 123 | ![]() | .~.~.~.~ Differential speed between two bodies |