The nature of brake fluids used before 1950 is outlined. Since then, development of synthetic materials, eg glycol ethers, polyglycols and borate esters, has produced fluids meeting the requirements of current specifications. The most widely recognised of which is FMVSS 116 which classifies performance levels at DOT 3, DOT 4 and DOT 5. The most important properties of brake fluids are summarised. The hygroscopic nature of most brake fluids, the effect of hygroscopicity on service life and measurement of in-service performance are discussed and compared to the properties of non-hygroscopic fluids such as silicone and mineral oil. More recent developments in brake fluids include improvements in borate ester materials and the introduction of silicon ester fluids (patented by Castrol in the 1970's). A summary of these developments is given. The discussion has outlined the historical development of brake fluids, the major requirements and some aspects of testing and specifications, and finally reviewed some recent technology developments.

  • Authors:
    • Van Tilborg, J E
  • Publication Date: 1989-1-2


  • English

Media Info

  • Pagination: p. 10-14
  • Serial:
    • REV T
    • Issue Number: 1-2

Subject/Index Terms

Filing Info

  • Accession Number: 00605867
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Mar 31 1991 12:00AM