5000-brick motorised LEGO model of the popular Twister amusement ride, also
known worldwide by various other names including the Twist, the Sizzler, the
Gee Whizzer, the Grasscutter, the Cyclone, the Cha Cha, and the Scrambler.

Three clockwise rotating suspended carriage assemblies with four carriages each
are rotated anti-clockwise around a central core. The opposing rotation of the
carriages to the core result in a sweeping sensation for the riders and the
illusion that the carriages are going to collide with each other. Larger
versions of the ride have the whole thing mounted on a raised platform.

All modern versions of this ride support the rotating carriage assemblies with
lower and upper arms connected to the central core and use a double wheel/tyre
mechanism on the lower arm that rotates the carriage assemblies as the arms
rotate around the base of the core. Much older versions of the ride only used
upper support arms containing gearing that rotated the carriage assemblies
from above and this is what I've done on the LEGO model since it avoids tyre
slippage and is a nice use of Technic gearing from a single motor.

My version of the model also includes an elevation mechanism that can raise the
carriages so that they rotate on a slightly tilted axis. I'm not sure if any
Twister has ever done this. Certainly none of the modern ones do, but I seem to
recall seeing one in the 70s that did. Or perhaps my mind is playing tricks
with me. Either way, this is LEGO, and the LEGO version elevates, so there!

Built with LDraw (MLCad) and rendered with POV-Ray.

Further information and images here:
http://equinoxe.byethost16.com/lego/twister/

Video:
http://www.youtube.com/watch?v=oFR6u9_lnoY