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).
Technical memorandum discussing the design of a servo mechanism, comparing swivel plates to a double cone scheme.
| Identifier | ExFiles\Box 73\1\ scan0123 | |
| Date | 25th March 1924 | |
| URGENT AND IMPORTANT. X.9910 To DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} ST.{Capt. P. R. Strong} ) FROM R.{Sir Henry Royce} c. to CJ. RG.{Mr Rowledge} BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} PN.{Mr Northey} S E C R E T. RL/M25.3.24. E.A.C. - N.SCH.1769 - Lec.1846. X.9910. SERVO. For the experimental ones in hand we shall not make the swivel plates but trust to the alignment being sufficiently correct. If we find difficulty in getting sufficient end pressure with say 30° thread, and we cannot have longer levers to the foot pedal (Which should be done in schemes like RRM. and DES.60) then we could get a multiplication of about 2½ by double cone scheme. (Before spending time on this which is inferior to the flat plates see that all other proportions are correct for reasons given - (heat and wear etc.) i.e. ferodo cones of about 30° which would be 2 to 1 approx, and the increased mean dia. would make this 2½ times. We must at once get sufficient assistance from the servo which we can reduce afterwards if advisable. We have failed somewhere perhaps because (1) through misunderstanding about the angle of the thread (2) not allowing the servo to move through a large angle - i.e. 75° for the full range, i.e. application and wear. I still believe this is wrong, and if so it will make the application too sudden, also not enough power, and too great heat in servo, with 3 to 1 reduction. If you allow your levers on the front axle clearance for a 2" stroke on the ropes then 80° should carry the front ropes this 2", and the back one 2" in RRM. scheme, and all others say 3" so as to permit 5/3 more leverage to the back brakes (with the same clearances and allowances for wear.) The floating lever could be increased in the horizontal arm and hung further back, say in 2 or 3 proportions. SEE ORIGINAL FOR SKETCHES. contd:- | ||