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).
Instruction sheet detailing tests on lubricated and graphitic brushes to reduce shrieking.
| Identifier | ExFiles\Box 60\1\ Scan239 | |
| Date | 25th November 1929 guessed | |
| RR 238 (150 BKS.) (DB{Donald Bastow - Suspensions} 461-8-12 24) MP 306975 ROLLS-ROYCE LTD. INSTRUCTIONS. To____________________________________________________ 19__ Order No. PD 53 (4) Customer's No.__________________ 2 Lubricated and Graphitic Brushes. The facts, that brushes were usually found to be quieter with a clean commutator, and that shrieking was often accompanied by perfect bedding of the brushes, pointed to the cause being a certain dirty condition of the commutator, with possibly a corresponding increase in the coefficient of friction. Consequently, a special grade of Morganite lubricated brush, EG6630, and more recently three grades of graphitic brush, were obtained. Details of these were given in reports PD17/2-2-28, PD43/10-2-30, and PD44/22-2-30. Further tests with these brushes are in progress. 3 and 4. Increased Bevel and Special Holder. A set of standard, EG2, brushes was taken and the bevels increased, by filing, from 15° to 60°. Tests were then carried out with combinations of:- (a) Standard holder and standard spring. (b) Standard holder and special spring. (Spring having a larger radius of arm, and made for use with brushes having increased bevel.) (c) Special holder (one with leading wall removed) and standard spring. Cont'd.{John DeLooze - Company Secretary} Signed__________________________________ This Sheet must be filed on completion of the work. | ||