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).
Preliminary report on the performance of Johns-Manville brake linings on car MX-4.
| Identifier | ExFiles\Box 26\4\ Scan381 | |
| Date | 10th May 1929 | |
| X2960 OY-11 May 10th, 1929. TO: Mr. Beaver Mr. Ross Mr. Bagnall Mr. Burton cc - Mr. Caswell Experimental Dept. Mr. Ainsworth Mr. Bailey (Eng.) Mr. Allen Mr. Hives (Eng.) Mr. Soutter FROM: Mr. Olley BRAKES MX{John H Maddocks - Chief Proving Officer}-4. The Johns-Manville linings have now been run 1300 miles on MX{John H Maddocks - Chief Proving Officer}-4 and have been examined twice, at 300 and 1300 miles. They are fitted front and rear. The ball bearing servo levers are used giving a multiplication of about 2 to 1. Previously the car had been run 4000 miles with Ferodo on the rear and with Ferodo, Tenoid, and Multibestos in front. All these linings had squeaked, and the rear brakes had started to squeak before 4000 miles were completed. Because of the obvious softness of the J-M linings, the drums which had become sharply scored in previous 4000 miles of test were carefully scraped and polished, to remove the cutting edges as far as possible. The results on J-M linings are of course inconclusive so far, but the difference in handling etc. of the car since fitting them is so remarkable that this preliminary report is being made:- (1) No squeak whatever, even when soaking wet in a severe thunderstorm, a condition which makes all other linings squeak at once. (2) The brake application is noticeably smoother, and the degree of braking easier to regulate. (3) We do not yet have means of testing the coefficient of friction, but the braking power is distinctly greater than with other types. (4) The equalization of braking effect from side to side appears to stay more constant than with other types. (5) The linings have taken on a high polish without scoring the drums and so far without measurable wear of the linings. -continued- | ||