Plastic bearings put roller coaster vehicles in a spin
The 'X' roller coaster at Six Flags theme park in California is thought
to be the first in the world to offer a ride in 'four' dimensions. In
addition to attaining top speeds of 76mph and plummeting down a sheer
drop of 200ft, the 20ft-wide, eight-passenger, wing-shaped vehicles are
able to spin 360 degrees, forward and backward, independently of the
train's primary movement.
One of the key specifications for the vehicle suspension bearings was
that they be maintenance- and lubrication-free because of difficulties
accessing them. Moreover, as the application required a high degree of
vibration damping, the bearing also had to have reasonable flexibility.
In the end, the design team chose iglidur Z plastic bearings from igus
and proceeded to put these components to the test.
After six months' continuous running during the high season, the team was
pleasantly surprised by the condition of the bearings. According to Six
Flags engineer, Jeff Hudgins, there was practically no wear at the
bearing or the shaft. Maintenance was thus reduced by about 95%, annual
costs for spare parts reduced by 55% and laboratory costs by around 9%.
The flexibility of the iglidur Z material and its tolerance of
misalignment errors also helped with bearing installation and removal.
*igus has introduced a plastic lead screw module, the DryLin SHTP, with
shaft diameters of 6mm and 12mm. The plastics used for the slides, end
blocks, bearings and nuts ensure a lightweight but sturdy structure that
is also corrosion resistant. The shafts are the only metal elements and
these are made from aluminium to minimise the weight of the module.