Available in the UK from Aerco, Adda's latest range of dc fans is now
fitted with fluid dynamic bearing (FDB) systems, which greatly increase
the life expectancy of these units. Indeed, the life expectancy of FDB's
at a nominal 25oC is 70,000 hours, compared with 50,000 for dual ball
bearings and 30,000 for sleeve bearings. The structure of the FDB ensures
that there is no metal contact between shaft and bearing. This is
achieved by a V-groove that generates fluid pressure on the inner surface
of a sintered metal sleeve, allowing a dynamic pressure to develop in the
centre of the shaft. The bearing also tolerates temperatures of up to
90°C.