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).
High-speed over-running rattles, flywheel dynamics, and potential solutions involving coupling elasticity.
Identifier | ExFiles\Box 25\3\ Scan029 | |
Date | 19th November 1911 | |
Copy R.M.S. DUNOTTAR CASTLE. November 19th. 1911. Referring to the high-speed over-running rattles, I do not think that we are on quite the right track. We have effectively two flywheels, i.e. the brake drum and the engine flywheel, coupled together with a practically rigid connection, and unless the axis of the gear box shaft and the crankshaft are parallel, there is a speed variation due to the coupling, and under very light loads could easily cause knocking. This view is supported by the fact that the rattle is worse at high speeds, when the flywheels should be most effective, and the speed variation due to varying pressure in the cylinder considerably less in quantity, also the speed variation due to change of kinetic energy in the pistons should make very little speed variation of the engine flywheel at any speed, such speed variation being constant for all speeds, and enormously greater in 4-cylinder than 6-cylinder; so that I think it is entirely a question of the coupling and the two flywheels. Unfortunately the shafts will never remain parrallel, but will vary with the weight and position of weight on the Chassis, so that I am rather inclined to introduce some slight elasticity (torsional) say 1 to 5 degs. for the full engine torque; some temporary arrangement could be made for this, such as cutting the central part of the coupling into a helical spring. Never mind its oil-retaining feature - many ways of doing this temporarily will suggest themselves, but take care not to overdo the elasticity or leave it too weak. X834 | ||