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).
Calculation of the torque required on the 40/50 servo gears for a limousine car.
| Identifier | ExFiles\Box 67\1\ scan0072 | |
| Date | 14th December 1927 | |
| X8370 Hs{Lord Ernest Hives - Chair}/RmL/LG14.12.27. TORQUE ON 40/50 SERVO GEARS. X8370 x8470 Maximum torque required from brakes is to lock the rear wheels on dry concrete. Take limousine car 8-EX : Rear wheel weight 32 cwts. = .8 . . Pull at rear tyres 25.6 cwts. Pull at 17" drum 48 cwts. Normal pressure required on shoes, brake lining friction being .3 = 144 cwts. . . . Servo must produce this pull through existing leverage: [Diagram of a lever system with the following labels:] .5", 4.5", 2.15, 3.35, 2.5", 2.5, 1.7, 2.05, P, 3.8, 3.8, 5.575 Pull required at P. assuming EAC.7. leverage :- 144 X .5/4.5 X 3.35/5.50 X 1.7/2.5 = 6.6 cwts. This is equivalent to a pull at the end of the servo 2.05" lever of :- 6.6 X 7.6/5.575 = 8.7 cwts. at 2.05" lever. Or torque from servo plates and servo driving shaft of 160 lbs.ft. say 170 lbs.ft. to allow for modifications to drums or leverage. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||