4th Dimension roller coaster

4th Dimension Roller Coaster
'X²' (formerly 'X') was the first 4th Dimension roller coaster in the world.
Status	In Production
First manufactured	2002
No. of installations	8
Manufacturers	Arrow Dynamics (Discontinued), S&S Worldwide, and Intamin
Riders per row	4
Restraint Style	Over-the-shoulder

A 4th Dimension Roller Coaster is a type of steel roller coaster whereby riders are rotated independently of the orientation of the track, generally about a horizontal axis that is perpendicular to the track. The cars do not necessarily need to be fixed to an angle.

John F. Mares, a corporate attorney, invented the 4th Dimension roller coaster concept in 1995 and holds six US patents related to the technology of their spinning seat systems: US Patent #'s 5,791,254, 6,098,549, 6,227,121, 6,386,115, 6,477,961 & 6,606,953. The first 4th Dimension roller coaster to be built, X², which opened at Six Flags Magic Mountain, United States in 2002, was designed and patented by Alan Schilke. In 2007, Intamin launched a variation of the 4th Dimension roller coaster under the name ZacSpin.

Arrow Dynamics was the first company to produce a 4th dimension roller coaster, lending its name to the ride style. The trains feature seats capable of rotating forward or backward, 360 degrees in a controlled spin. This is achieved by having four rails on the track; two acting as per normal, and two to control the spin of the seats. The two rails that control the spin of the seats, known as "X Rails", vary in height relative to the track, and spin the train using a rack and pinion gear mechanism.

The first installation, X², was a prototype and cost Arrow Dynamics and Six Flags itself a lot of money due to technical difficulties and design flaws. In 2002, the park sued Arrow Dynamics, which went into bankruptcy. Since then Arrow was bought out by S&S Worldwide and became the company's steel coaster division, S&S Arrow. In 2006, a second installation opened at Fuji-Q Highland in Fujiyoshida, Yamanashi Japan under the name Eejanaika. A third installation opened in 2012 at China Dinosaurs Park in China under the name Dinoconda.