THE USE OF DRY LUBRICATED BEARINGS IN REACTION WHEELS

摘要

Over the last 11 years SSTL has successfully beenrnflying reaction wheels with self-lubricating (i.e. dry)rnbearings on all of its missions and has supplied wheelsrnto other space programmes world wide, totalling overrn100 wheels in orbit or awaiting launch. During thatrntime the typical mission life has extended from 3 to 7.5rnyears, increasing the demand on the self-lubricatingrnbearings which dependent upon transfer of a PTFE,rnchopped glass-fibre/MoS2 cage material (PGM-HT)rnfrom balls to raceways, a process ultimately limited byrnwear-out of the cage.rnThe increased life requirements are not without theirrnchallenges for this type of lubricant and coupled withrnoften very short concept-to-flight development andrndelivery schedules of typically less than 18 monthsrnthere is the need to be able to qualify wheels quickly.rnThis paper discusses the successful development andrnlife testing of the SSTL 200SP wheel which is anrnevolution of the SSTL microsat wheel and highlightsrnsome of the challenges, important considerations andrnlessons learned from the development and acceleratedrntest campaigns.