Zaturn / 213 ft (65 m) / 81 mph (130 km/h) / Space World, Japan / 2006
The Accelerator Coaster is Intamin AG's term for their hydraulically-launched roller coaster model. These models are the tradename for some of the fastest rides on earth.
An accelerator coaster is named because of its long, straight launch track, its tower, known as a "top hat", and its magnetic brakes that smoothly stop the train without touching it. After the top hat, the layout varies widely, ranging from a flat brake run to several inversions.
If this type of coaster is not launched fast enough to clear the top hat (which can happen for several reasons), it will roll backwards down the tower and along the launch track. For this reason, the launch track is fitted with retractable brakes that are retracted for the launch and extended at all other times. The main brake run uses the same type of brakes, which are fixed in place.
An Accelerator Coaster's hydraulic launch is much smoother than other launch technologies such as linear motors. While a linear motor-launched train's acceleration is greatest at the beginning of the launch and decreases throughout the launch, a hydraulic launch produces nearly constant acceleration throughout the launch.
Most accelerator coasters are launched from the station, but there are some that advance the train to a separate launch area, either for theming reasons (Superman Escape) or to allow multiple trains to be loaded simultaneously (Top Thrill Dragster, Kingda Ka).