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).
Oil pressures within a 2-speed gear operating cylinder during gear changes.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan273 | |
| Date | 17th September 1925 | |
| R.R. 493a (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -3a- Expl. No. REF:- AR/LG.17.9.25. was therefore fitted to the pipe connecting the scavenger pump to the 2-speed gear operating cylinder, and oil pressures observed when changing gear. With cold oil at a temp. of 17°C a max. pressure of 85 lbs/sq.in. was observed when changing, but after running a few minutes this fell to 45 lbs/sq.in. The engine was run at different speeds up to that at which the control valve allows oil to bye-pass the operating cyl:, but for normal oil temperatures (60°C) the pressure recorded in the system when changing gear was about 45 lbs/sq.in. at all speeds tried. Mid-position of change speed valve. It was thought that the change speed valve might be covering both admission ports to the cylinder at once when in the mid-position, thus completely blocking up the oil-way through the cylinder, but this was not so, the pressures obtained with the change speed lever in the mid-position being 10 lbs/sq.in. changing from low gear to high - 40 lbs/sq.in. changing from high gear to low. Observing the oil flow at the outlet from the operating cylinder showed that quite a large volume of oil was passing the valve when the latter was in the mid-position, and hence concluded either that the valve was not covering both admission ports at once, or the valve itself was lifting from its seat against the spring. As, however, little leak seemed to be taking place from the front end of the valve, it was concluded that the latter was not lifting appreciably. Marking the valve with prussian blue showed that in the mid-position both admission ports were open slightly, the width of the opening being about 1/32". contd :- | ||