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).
Secret memo discussing design improvements and issues related to a servo mechanism, including its action, levers, rods, and pressure unit.
| Identifier | ExFiles\Box 73\1\ scan0147 | |
| Date | 14th April 1924 | |
| X9919 X.9940 To E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} & 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} SECRET. R2/M14.4.24. EAC. 2 and 3. SERVO. X.9940 Further to my two former memos. I agree that the servo should have a stop to limit its action to about 90° forwards, and say 75° backwards. I think the lifting links given by Mr. Day and mentioned by you in your report very good, but possibly it would be better :- (1) Not to superimpose the levers because of the friction created, reducing the efficiency and increasing the tendency to stick on. (2) Not to risk catching the rods if end positions in-correct or worn. My suggestion is :- SEE ORIGINAL FOR SKETCH. In the earlier design the inner pressure plate was fixed on the inner shaft. This would prevent cross winding on pins. I do not see any disadvantage of making it thus. In my last memo. I shewed plan of balance lever to provide for con. rods being in 2 planes about ¼" apart. SEE ORIGINAL FOR SKETCH. It will be noticed that the 3 driving pins also carry the small load due to lifting link which falls on this end but this is advisable so that 3 pins drive equally without binding of main driving plate - In this arrangement the whole of the pressure unit is outside bearing: one half is on pressure bolt, the other on end of main driving plate - SEE ORIGINAL FOR SKETCH. I have received RG{Mr Rowledge}'s notes to say jaggers re-appeared. You will remember that I suggested these would force us to fairly slow speed servo. Foot to B.A. only (RRM) might possibly help this. I do not favour too little pressure required from foot for 2 or 3 reasons - emergency, smashing something. Habit will prevent us having enough direct pressure for close driving. My centre bolt is as free as it can possibly be. R.{Sir Henry Royce} | ||