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).
Automatic advance mechanism issues for the Phantom model, including magneto noise and governor modifications.
| Identifier | ExFiles\Box 37\1\ scan 301 | |
| Date | 4th May 1926 | |
| To Hs{Lord Ernest Hives - Chair}/HM.{Capt. W. Hallam - Head Repairs} from R.{Sir Henry Royce} EFC c. to BJ Wor.{Arthur Wormald - General Works Manager} Hy.{Tom Haldenby - Plant Engineer} X3949 RL/M4.5.26. PHANTOM AUTO. ADVANCE. X.8685. X.3949. (A) Referring to your memo of 23.4.26. I understand the noise is caused by the swing of the magneto sleeve due to the positive and negative torque. It is difficult to understand why a spring cannot be used to keep this sleeve in one direction, together with a certain amount of friction to damp it against the slight oscillation caused by the elasticity of the control. As far as I can understand this is actually taking place on 7-EX. The cause of the noise in the magneto with part friction and part retard spring should be found. (B) Regarding the relay piston this ought to be sufficiently free for it to fall to the zero position by its own weight, which we should think is somewhere about half a pound. We find that 6 lbs. to retard it, and the controls and distributor, is sufficient and safe. Actually 7-EX is working without a spring at all except the one on the magneto which may be 3 lbs. Since we allow much leak for clearance in the central control valve we do not need a very oiltight large piston. 7-EX piston with leather is quite free, and seems very good. It should, however, have a definite metal stop by collar (see LeC.2242) because lower edge of leather might get jammed in undercut. Stop collar and undercut should be arranged so that the leather cannot reach undercut. Possibly leather is undesirable. Try close fitting piston and spring ring. (C) Regarding the modifications you propose to make we think it would be quite wrong to reduce the governor weights. We have done all we can to get these weights powerful so as to make the governor powerful as it only runs at half crankshaft speed. We would much rather re-arrange the governor springing if it is found necessary, but we think there should be no difficulty with the apparatus. Do not use any initial set on the governor spring because we have some gravity from the central relay control piston to assist pulling the governor weights to zero. We think it is this gravity, plus the 8° initial set on the spring, which makes the governor not operate until it is revolving at 375., equalling 750 crankshaft speed. If we do away with the 8° of initial set and use the gravity of the central piston we still ought to be sure of this piston | ||