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).
Analysis of engine vibrations and dampers for the 20 HP engine, including considerations for increasing the master period.
| Identifier | ExFiles\Box 22\4\ Scan137 | |
| Date | 22th April 1927 guessed | |
| contd :- -11- the spring drive as pointed out by Mr. Royce in a memo. with regard to F.10. The 1-G-1 type of damper is a means of springing most of the forward mass and as this seems a promising alternative to the friction type we are testing it more fully on 1-G-1. Therefore from consideration of these factors we think the 'master period' of the present 20 HP. engine could be raised to a speed safely outside our working speed range - probably somewhere about 3700 r.p.m. - by increasing the crankshaft stiff- ness similar to the experimental one at one time constructed for the 20 HP. - and by reducing the inertia of those parts of the spring and slipper drive which are rigid with the crankshaft. We should estimate that by increasing the crankshaft stiffness 15% and reducing the hub inertia at the front end to one half of its present value the master period would be put up to somewhere about 3690 r.p.m. This would mean that lower gear ratios could be employed with safety. With regard to the slipping wheel itself, the present one seems to possess just about the right inertia to deal with the harmonics. AMPLITUDE OF THE VARIOUS VIBRATIONS ON STANDARD 20 HP. WITHOUT DAMPER. We have analysed a considerable number of vibration diagrams taken on a std. 20 HP. at full load without a damper and plotted the amplitude of these against the engine and road speed. (See appended print). It will be observed that the 'master vibration' contd :- | ||