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).
Historical outline and test results for the braking system on S.S. cars.
Identifier | ExFiles\Box 16\3\ Scan043 | |
Date | 19th April 1929 | |
To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} x7370 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/1019.4.29. 'SS{S. Smith}' BRAKES. x7420 We have been making continuous tests with the braking system on S.S. cars and consider it is desirable to outline the history of the brakes up to date. The first S.S. cars built up appeared to suffer from : (1) Insufficient total braking units for a given pedal pressure. (2) Front to rear proportioning did not correspond to theoretical anticipations. Measurement of the servo efficiency demonstrated that this was below expectations and in order to provide the cars with reasonable braking while further investigations were going on the servo cam angle was altered from 45o to 30o, thus doubling the end pressure transmitted to the servo for a given pedal pressure. At the same time the direct braking leverage was made similar to that on the Phantom to overcome the feeling of sponginess when making a rapid stop. The effect of this modification was to give the cars quite reasonable brakes, but it was noticeable that : (1) The efficiency of the brakes xx fell off as the car warmed up. (2) The braking was not proportional to the pedal pressure. Moderate deceleration easily obtained. Maximum deceleration required enormous pedal pressure with contd :- | ||