Roller coaster

Steel Dragon 2000 roller coaster in Nagasaki, Japan, one of the tallest in the world.
©CoasterGallery.com (Used by permission)

A Roller coaster is an amusement ride designed for amusement parks and modern theme parks. It consists of an elevated railway that carries a train through changes in speed and direction.

At first glance, connected roller coaster cars look much like a passenger train. But unlike a train, it is not powered by a motor, but by gravity and momentum. To build up the ride's momentum it must first climb the first hill (or lift hill) by use of a lifting mechanism called a chain lift. The lift usually consists of one or more chains running under the track. The chain is fastened in a loop and wound around a motor-powered gear at both ends of the hill. The motor turns the chain loop, propelling the coaster train up the hill like a conveyor belt. The cars are attached to the chain by several hinged hooks called chain dogs. In recent designs, the use of catapult-launching techniques is sometimes implemented.

After the coaster climbs the hill it travels down the first, and often sharpest, drop. The entertainment of the ride is provided by the velocity of the descent as well as features such as inverted loops, banked curves, and barrel rolls that produce g-forces that press down on riders. "Negative g-forces" give the rider a sense of weightlessness at the peak of hills.

Roller coaster types

There are two main types of roller coasters, mainly distinguished by their track structure, wooden roller coasters and steel roller coasters.

Wooden roller coasters are coasters with tracks made out of wood and have tracks similar to traditional railroad tracks. Often the wheels of these types of coasters will have the same wheel design as that of a train, with the inner part of the wheel having a wide lip that keeps the train from rolling off the tracks. Another set of wheels keep the train from flying into the air. The tracks of these coasters are braced by diagonal support beams and wooden cross ties and the track structure itself rests on a lattice of wooden or sometimes steel beams. Unlike that of steel coasters, the track structure is for the most part inflexible, because of it's wooden material. This makes complex twists and turns difficult to implement. Instead most wooden roller coasters simply go up and down.

Steel roller coasters, on the other hand, have a much more flexible design and can greatly expand the range of motion. Many of these types of coasters run on tubular steel tracks, introduced in the 1950s. These tracks consist of two long, steel tubes, supported by a lightweight structure composed of steel tubes. The wheels of coasters that run on these tracks are made out of polyurethane or nylon. Steel roller coasters provide the opportunity for much sharper and complex twists and turns as well as loops, barrel rolls, and other inversions not possible with wooden ones.

Though many tubular steel coasters rest on top of the track, they may also attach to the bottom of the track in what is called a suspended roller coaster. These hanging trains swing from a pivoted joint, making the train move from side to side. An inverted roller coaster also uses this method, but has the train rigidly attached to the track to give more precise control over the trains movement.

As of 2008, there are 2,176 roller coasters operational around the world, 2,008 of them steel and 168 of them wooden. There are eight main roller coaster types:

• Sit-down
• Stand-up
• Suspended
• Inverted
• Pipeline - where riders are positioned between the rails as opposed to above or below.
• Bobsled - where riders ride freely through a trough, like a bobsled run.
• Flying - where riders are positioned parallel with the track, giving them a sense of flying.
• Fourth Dimension - where cars, positioned on either side of the track, spin on a horizontal axis.