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).
Brake tests comparing standard brakes with ribbed cast iron and steel brake drums on Phantom II cars.
| Identifier | ExFiles\Box 120\1\ scan0045 | |
| Date | 13th April 1941 | |
| X4612. To Sg.{Arthur F. Sidgreaves - MD} From Hs.{Lord Ernest Hives - Chair} c. to Wor.{Arthur Wormald - General Works Manager} c. to FN. Hs.{Lord Ernest Hives - Chair}4/MJ.13.4.41. X.7360. X.4612. re Brakes on P.11's. Replying to Sgl7/E10.4.31. We have carried out tests which confirm that the present brakes fitted to our cars lose considerably in efficiency after they have been used to any extent. We have also proved that with the ribbed brake drums the brakes retain their efficiency no matter how much they are used. The steel ribbed brake drums would be much more expensive than the present drums. We therefore carried out tests with them made in cast iron. On the cast iron drum we have had trouble with cracks developing, this has been taken up with the makers and further castings are being made in different cast iron. We have not found that the ribbed drums overcome brake squeaks. There may be a slight improvement, but we cannot look forward to brake squeaks being overcome with ribbed brake drums. Another feature is that the additional weight of the ribbed drums on the front axle increases our steering troubles and frame jellying. The position at the moment is that tests are still in progress and we hope at least to be able to recommend the ribbed brake drums at the rear, which should give us very definite improvement. A further report on this will be sent in due course. Hs.{Lord Ernest Hives - Chair} | ||