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).
Investigation into the causes of over-run booms on a 25 HP Japan Engine (1V-G6).
| Identifier | ExFiles\Box 181\M13\M13.2\ img002 | |
| Date | 8th December 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/GR.{George Ratcliffe} c. to Sk. c. to Wor.{Arthur Wormald - General Works Manager} c. to Ds. c. to E.{Mr Elliott - Chief Engineer} c. to Hy.{Tom Haldenby - Plant Engineer} c. to EV.{Ivan Evernden - coachwork} BOOMS ON 25 HP. (JAPAN ENGINE 1V-G6). We have found that the over-run booms are caused by both engine vibration and the exhaust system both taking place at the same speed. Engine Booms. Removing the rocker shaft eliminated the booms due to the exhaust system. We found that the engine boom was diminished 75% by removing the torque reaction dampers and that the remaining 25% disappeared on disconnecting the rear engine feet; the gearbox being supported by ropes round a bar resting on the frame. Exhaust Booms. Running the engine supported so that the booms due to vibration were absent we were able to examine the exhaust booms. The important boom at 2350 R.P.M. 50 M.P.H. in top gear, is much reduced when the exhaust system is hot (engine temperature having no effect). With the exhaust system cold booms occur at 1250 R.P.M. 1900 R.P.M., 2350 R.P.M., and 2575 upwards. With the exhaust system hot the two lower booms 1250 and 1900 R.P.M., and the high speed one, decrease in amplitude. (1) Removal of the swan-neck bracket on the pressed steel cross member had no effect hot or cold. (2) Removal of the rear silencer support (swan neck support still absent) slightly decreased the magnitude of the booms. (3) Removal also of both down take supports left the booms as in the last experiment. (4) The entire exhaust system isolated and held up by an asbestos rope did not suppress the booms when cold, but the booms decreased as before with the exhaust system hot. | ||