From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Letter to Morgan Crossley & Co. Ltd. discussing brake lining pressure and coefficients of friction.
| Identifier | ExFiles\Box 26\4\ Scan351 | |
| Date | 28th October 1927 | |
| 73409 Expl: Dept: Hs{Lord Ernest Hives - Chair}/Rn{Mr Robinson}4/LG. 28th. Oct. 1927. Messrs. Morgan Crossley & Co. Ltd., Miles Platting, Manchester. Dear Sirs, Further to our conversation with your representative today. We find that the unit pressure which we are working to is 150 lbs/sq. in. for a co-efficient of friction of .3 of the brake lining, in the case of a sudden stop. Naturally, on a touring car this pressure is seldom, if ever, maintained for more than three or four seconds at widely spaced periods. Messrs. Ferodo give the co-efficient of their standard bonded asbestos as .35, and that of Ferodo fibre .5. Actually in service we do not obtain anything much higher than .25 and .4. In order to minimise the alteration which will be necessitated to our brake leverage, we suggest that the material you give us a co-efficient of friction of not less than .25 by your test, and has wearing qualities which are similar to those of Ferodo bonded asbestos. One of our main concerns with this lining is that of avoiding squeaks. Yours faithfully, | ||