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).
Loss of braking efficiency after washing a car, attributed to the design of the pivoted brake shoe.
| Identifier | ExFiles\Box 84\2\ scan0118 | |
| Date | 12th February 1934 | |
| GRK x206 Hs.{Lord Ernest Hives - Chair} from Hy.{Tom Haldenby - Plant Engineer} Copy to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} By.{R.W. Bailey - Chief Engineer} [Strikethrough] See me HS{Lord Ernest Hives - Chair} [Handwritten] Hy{Tom Haldenby - Plant Engineer}5/T12.2.34. Re loss of braking efficiency after washing car. It has occurred to me that our troubles may be more pronounced than usual because of the use of the pivoted brake shoe. The small pivoted shoe in its present form constitutes a very good Michell bearing pad, and while the brake is dry, no detrimental effect will be produced. Immediately any lubrication, such as oil or even water, is applied, the Michell pad will operate and have the effect of preventing the leading shoe coming into proper contact with the brake drum. The only braking effort available being produced by the trailing shoe, which, as is well known, is small compared with that of the leading shoe. I suggest that tests be made, with and without the pivoted shoe in action, the tests being made in a lubricated condition. It is realised that the 40/50 does not suffer to the same extent as the Bentley, but it may be that the more powerful servo motor of the 40/50 breaks down the lubricating film. Although the Bentley has the same servo motor as the 20/25, it is to be noted that the 20/25 rear brakes are not fitted with pivoted brake shoes, only the front brakes being so fitted. Hy.{Tom Haldenby - Plant Engineer} [Signature] | ||