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).
Proposed modifications to the Bentley servo and brake leverages.
| Identifier | ExFiles\Box 87\5\ scan0054 | |
| Date | 11th March 1935 | |
| Handwritten Text: +MI Rasa GRY.{Shadwell Grylls} This move seems to invite increase in heating up. HDY{William Hardy}/HP.11.3.35. Rm{William Robotham - Chief Engineer} Typed Text: To BY.{R.W. Bailey - Chief Engineer} and Hs.{Lord Ernest Hives - Chair} from HDY.{William Hardy} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} RHC.{R. H. Coverley - Production Engineer} Modifications to Bentley Servo and Brake Leverages. N. Sch's 4393 and 4406 herewith show what we propose to prevent the servo reaching the stop before the pedal is down to the board. With the present layout, when the pedal is on the board, and the servo on the stop, the travel available for the front brakes at the end of the lever on the front axle is 1.080" whereas the lever can move 1.850" before contact is made with the front axle or at any other part of the axle brake gear. The layout shown by N. Sch.4393 provides the 1.850 travel for the front ropes and an extra .250" to guard against their being more sponge between the servo and the front end of the front brake ropes than between the servo and the rear compensating shaft. The increase of work that is required from the servo is 44%. We propose to obtain 8% of this by increasing the maximum rotation of the servo from 81° to 90° which can be done if we have longer levers on the servo as we show. The balance of the increase of work must be obtained by altering the cam angle to 36° which gives a 36% increase of end load. The increase of length of the servo levers from 1.750" to 2.0" reduces the increase of load in the adjacent rods and levers from 44% which would be necessary with 1.750" levers and no increase of servo rotation, to 36 x 1.750 / 2.0 = 31.5%, | ||