| 310 / | HD | ELECTRICAL GENERATOR OR MOTOR STRUCTURE |
| 300 | DF | NON-DYNAMOELECTRIC {4} |
| 311 | DF | .~ Piezoelectric elements and devices {17} |
| 321 | DF | .~.~ Combined with resonant structure {4} |
| 323.01 | DF | .~.~.~ Direct mechanical coupling {5} |
| 323.02 | DF | .~.~.~.~ Motor producing continual motion {3} |
| 323.12 | DF | .~.~.~.~.~ Langevin or pencil type motor {1} |
| 323.13 | DF | .~.~.~.~.~.~ Output member detail {2} |
| 323.15 | ![]() | .~.~.~.~.~.~.~ Material or material property |