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).
Difficulties encountered with the governor spring, oil relay piston, and cold oil effects.
| Identifier | ExFiles\Box 65\1\ scan0023 | |
| Date | 11th December 1924 guessed | |
| contd :- -2- governor spring 2/3 the rating. Though this gives the correct advance at very low speeds it is no use higher up the scale, it is also unsuitable for reasons described later. The chief difficulties we have encountered are :- (1) In order to return the governor weights to the 45° position when connected to the oil relay, an initial set up in the springs of about 1/3 lbs. is necessary. This indicates the friction present. With the spring to cut the governor out at 2000 r.p.m. we cannot get an appreciable advance before 750 r.p.m. (2) The small inner relay piston is highly susceptible to impurities in the circulating oil. The original piston was made in steel and had a tendency to stick in almost any position when the engine speed was suddenly reduced. We have now a piston made in brass and by slightly increased clearance expect to reduce this trouble. (3) When using light governor springs to obtain advance at 500 r.p.m., we get a peculiar effect when the oil is cold and viscosity high. As soon as the governor lifts the small piston and admist oil to the relay, the large piston moves up and carries the former with it against the light governor spring due to the stiction of the cold oil. This continues to the full advanced position where both remain. As no oil is circulating in this position, they are liable to remain thus for a considerable period, though the engine may be running at low speeds. contd :- | ||