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 concerning brake squeaking issues with test linings and the potential use of lubricants.
| Identifier | ExFiles\Box 140\4\ scan0014 | |
| Date | 28th June 1937 | |
| 1181 Rm{William Robotham - Chief Engineer}/AFM{Anthony F. Martindale}3/R.{Sir Henry Royce} 28th June, 1937. British Belting & Asbestos Ltd., Scandinavia Mills, CLECKHEATON. For the attention of Mr. E.W. Sisman. Dear Sirs, BRAKE SQUEAKS. You will recollect that recently you very kindly supplied us with several sets of Halo III and Halo V.{VIENNA} for test purposes, but that we have not been able to fit them to any chassis as we found they squeaked on our test rig, a fact that we were able to demonstrate to Mr. Dalmaine. We regard this as a great pity, and we think perhaps you might like to know the constituents of linings which on our rig and cars have been fairly successful in reducing squeaking. This information we have obtained for ourselves as we are unable to obtain any reliable information on the subject of squeaks from outside sources. We consider that brake linings need to contain some lubricant to prevent fluctuations in the relative speed between drum and lining, which causes the squeak. This lubricant does not necessarily reduce the co-efficient of friction, on the contrary, it sometimes raises it. All the linings we have tried having such properties have had a high coefficient of friction, but unlike your Halo III are not harsh. The only two lubricants we have tried are metallic lead and boiled castor oil, of the type used in non-drying paint. We believe Ferodo Ltd. may have a patent on the latter ingredient, but we have not looked into the matter. The lead bonded linings we have tried have contained 13% by weight of lead which has been in the form of wire woven | ||