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).
Explanation of the forces and operation of the magneto hand control relay and pressure piston.
| Identifier | ExFiles\Box 65\1\ scan0126 | |
| Date | 16th February 1926 guessed | |
| contd :- -5- the stiction with the engine stationary being counter-balanced by the fact that when running the cam action tends to retard the magneto to all the time. The condition is therefore that with 15 lbs/sq.in. oil pressure, the relay can only just operate the controls under normal conditions if no return is fitted above the pressure piston. Now in order that the hand control of the magneto can operate satisfactorily, the return spring must have a minimum load of 10 lbs. on the piston of the relay. The reason for this is as follows. When the hand quadrant is moved to the fully advanced position, the magneto is advanced and rods X, and Y, are in compression. Lever A, is pushed against a stop. When the hand control is retarded, on the contrary, in order to retard the magneto, rods X, and Y, are in tension and lever A, tends to move away from the stop. Now unless there is some force tending to keep lever A, in its position which is greater than the force exerted in rod X, due to the resistance to movement set up by the friction of the magneto sleeve, lever A, will advance instead of the magneto retarding. It is found that the minimum force required is 10 lbs. on the top of the pressure piston. The relay must therefore be capable contd :- | ||