The accelerator (gas pedal) in a vehicle; figuratively, to increase speed or intensity.
右足でアクセルを踏んで、車の速度を上げた。
He pressed the accelerator with his right foot and increased the car's speed.
プロジェクトが進まないので、マネージャーがアクセルを踏んだ。
The project wasn't progressing, so the manager stepped on the accelerator (took action to speed it up).
アクセルが戻らなくて緊急停止した。
The accelerator wouldn't return and the car had to stop urgently.