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).
The testing of a water exclusion scheme to prevent Bentley brake judders.
| Identifier | ExFiles\Box 84\2\ scan0110 | |
| Date | 27th February 1934 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Ha/Gry.{Shadwell Grylls} c. to Nor. c. to L. c. to By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} X206 Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}11/KW.27.2.34. Bentley Brake Judder. Water Exclusion Scheme - N.Sch.3973. We have tried this scheme on 3-B-IV to prevent water getting on the front brakes when washing the car. In order to carry out the experiment exactly to the N.Sch., new drums were required. We arranged therefore with Da.{Bernard Day - Chassis Design} that we should alter the baffle slightly to try it out on existing brake drums. The clearance between the baffle and the first rib we made .038" which is nearer than we could use on production. We played a hose on the front brakes and then immediately removed the brake drums, to find everything within the drums wet. A road test confirmed that after washing the car inefficiency followed by judders was not effected by this scheme. To make sure that no water entered by the drainage holes we blocked these up but could notice no difference in the behaviour of the car. We have an impression that the exclusion scheme causes it to take a longer time before the brakes are again 100%, either because it is more difficult for the water to escape from the drum or because the recess retains water which continues to get into the drum. We conclude that it is inevitable that no scheme to prevent water entering the drums will be efficacious against a high pressure hose, and that the inefficiency and juddering must be cured by other means. Hs{Lord Ernest Hives - Chair}/H.Grylls. | ||