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).
Technical memorandum discussing issues with violent front braking on Peregrine brakes and proposed solutions.
| Identifier | ExFiles\Box 1\10\ B001_X106 TO X 110-page005 | |
| Date | 8th September 1932 | |
| To BY.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} C. E.{Mr Elliott - Chief Engineer} RHC.{R. H. Coverley - Production Engineer} x106. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}17/KR. 8.9.32. PEREGRINE BRAKES. On the original Peregrine we got most violent brake thumps, and obviously too much front braking. We therefore made careful practical measurements of the servo efficiency, and from the results calculated the actual front and rear braking we expect from the leverages which were to R.R. Sch.192. We attach a diagrammatic representation, Hs.{Lord Ernest Hives - Chair}692, of these levers, and a chart showing the brake distribution resulted therefrom with various servo efficiencies. It will be observed from this graph that reading for a servo multiplication of 2.8 we get (Measured 55% braking on the front. This accounted for our (efficiency trouble, and to overcome it we altered the length of the levers on the front brake equaliser shaft, increasing their length from 1.625" to 2.500". This reduced the front braking to 44% and seems about what is required, being approximately the ratio of the static weight on the respective axles. For the first six cars we think the leverages should be modified to give this ratio - this was not mentioned in E7/HP13. 8.32. the conference on Peregrine. We think that the same ratio of front to rear braking should be maintained when the direct brake operation is coupled to the front as well as the rear brakes. If this scheme overcomes thumping, we may be able to increase the front ratio slightly again as this fault at present is mainly the governing feature. With regard to the direct braking units. It will be observed that at present these are 220 only. We think if the foot operation is to go to the front and rear, these units should be increased to about 400. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||