Arabian Gulf--Complete reliability from a ring slide system. That's what Raceprep, a specialty hi-tech engineering company, needed to carry out a contract to design and build a 90m-high, 3D structure for the Jumeirah Beach Hotel Complex on the Arabian Gulf.
The diorama depicts the moving phases of the moon in front of a galaxy of stars and a structured model of the globe. The stars' pattern replicates their formation on the day the United Arab Emirates (UAE) was formed in 1971. "It is a very complex piece of engineering that provides a true-life picture of the sky at night," says Stephen Foster, managing director of Raceprep.
When it came to specifying a mechanism that could turn the 3m-diameter moon 360 degrees while ascending and descending a 32-m pole, Raceprep knew what it needed. "Quite simply," commented the company's technical director, Mike Rutherfoord, "we wanted the best-available ring slide that would offer a very long operational life and need no maintenance. The Hepco ring slide system met those needs."
Raceprep specified a Hepco gear-driven ring with a 1,033-mm diameter--the largest ring available in Hepco's standard range. This internally geared, 76-mm-wide slide ring was supplied in two 180-degree segments, which were exactly matched by Hepco. Designers decided to use the ring in two pieces to accommodate the inner circumference of the moon's shell and maintain scale. Since cutting off one ring would remove too much material to match the two halves up again, the one-halved ring is actually made from two complete rings, each cut to give exactly 180-degree segments. Because the ring is pinion-driven, the only thing left to do was match up the gear teeth. This was achieved through high-precision cutting and matching.
The system's life is at least five years, with maintenance checks only twice a year during this time. A long operational life is required because replacing the ring would be too costly. Minimal maintenance is also key because the ring runs up and down a pole mounted vertically up the inside of a building (20 stories and approximately 90-m high), making the point that the diorama, not very accessible to any regular maintenance, would disrupt hotel operations.
The system uses the same technology as its Generation II straight slides, and precision ground slides and hardened vee-face(s) ensure high levels of accuracy and wear resistance. In addition, eccentric bearing assemblies, which oppose concentric bearings, allow simple hand adjustments to minimize play and friction.
Gear drive options are available with teeth machined into either the internal or external register face. The number of teeth on the standard external option is divisible by 12 in order to provide maximum choice of pinion size for exact ratio requirements.