push-pull

Meanings

1. Operated by pushing and pulling.
2. Operating with locomotives at both the head and rear of a train, or with a locomotive at one end and a driving position in the vehicle at the opposite end, so that the train can be driven from either end.
3. Having two electronic devices in opposite phase.

1. An alternation or fluctuation between two opposites; a back-and-forth dispute, a tug of war.