With the increasing use of ultra-high speed magnetic bearing systems has
come the demand for better performing emergency touchdown bearings, which
are required to support the shaft in the event of magnetic bearing
failure. Barden has produced touchdown bearings for turbo-molecular pumps
for many years and has introduced a number of innovations, including a
single bearing alternative to the traditional matched pair, which has
reduced both cost and the amount of space required by this special
bearing assembly.
The company's latest development sees the combination of Barden's
Cronidur 30 ring steel and silicon nitride balls, a revised internal
design and a specially finished raceway surface that reduces ball skid
and wear. The new bearing achieves longer life (up to ten times the
number of touchdowns is claimed), higher reliability, quieter running and
improved corrosion resistance.