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).
Experiments to investigate vibrations in a 25 HP engine.
| Identifier | ExFiles\Box 5\6\ 06-page085 | |
| Date | 5th November 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/GR.{George Ratcliffe} c. to Sg.{Arthur F. Sidgreaves - MD} Sor. c. to H.{Arthur M. Hanbury - Head Complaints} DA.{Bernard Day - Chassis Design} c. to RY. Hs{Lord Ernest Hives - Chair}/GR.{George Ratcliffe}1/W.5.11.30. 25 HP. VIBRATIONS. Continuing our report Hs{Lord Ernest Hives - Chair}/GR.{George Ratcliffe}1/W.20.10.30.. we have made the following further experiments- (1) Stiffening the back of the flywheel had no effect. (2) Engine motored with bare crankshaft, pistons, connecting rods and flywheel being absent. Engine still rough. (3) Engine motored with plain parallel shaft and no flywheel, was perfectly smooth up to any speed. (4) Engine motored with parallel shaft and standard flywheel and clutch, was not so smooth as (3) and developed a period at 4500 R.P.M. (5) An engine testing bearing metals running on the bed with a 1 1/2" pin crankshaft has a flywheel period at 3100 R.P.M. Experiments of static deflections had shown us that the back of the flywheel bends under load. We therefore bolted to it a steel plate with two circles of bolts. On to this plate was rivetted the inner Ferodo. The pistons and rods were absent. The period still began at 2900 R.P.M. being over at 3400. The engine was then smooth but noisy up to 4600 R.P.M. where a vibration began, lasting up to 5400 R.P.M. To make sure that these vibrations are really due to the flywheel we towed the car (12-GIV) with no flywheel only a bare crankshaft being present. The drive from the gear box was by means of our rubber-bushed drive. A much smaller period could again be felt at 2900 R.P.M., which | ||