Marshall, O'Toole, Gerstein, Murray & Borun
Ring seal assembly
 The sealing ring seals between relatively rotating and vibrating machine parts such as parts of an aircraft propeller, and has several sealing lands. The shape and configuration of the lands are selected so that natural vibration frequencies of the ring or lands are not vibration frequencies to which the ring is subject in use. 
Dowty Aerospace Gloucester Limited
Y B Y
Y10S B64C Y10S
additional inventional additional
Thomas Noel Stephen John Bowen
Brown Parker