Pendulum rides are amusement rides based on the motion of a fixed pendulum. The configuration of the ride consists of a gondola, arm, and an axle. One end of the arm is fitted with a passenger-carrying gondola, while the other is attached to the axle. On some models, the arm extends beyond the axle and is fitted with a heavy counterweight. The counterweight is often used when the gondola swings through an inversion. In addition to swinging back and forth, some designs incorporate rotating gondolas and may send riders through a complete inversion. Pendulum rides are propelled by one of two methods: a series of DC motors driving the axle, or wheels at the base of the station pushing the gondola as it swings by.