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 friction torque from preliminary tests on the Phantom model.
| Identifier | ExFiles\Box 25\3\ Scan141 | |
| Date | 20th September 1926 guessed | |
| contd :- -3- figures because with the high unit pressures necessary on the slipping surfaces, the friction torque became extremely erratic and was particularly susceptible to changes of temperature when on the engine. With loads of this order it would seem essential to employ multiple friction plates. The reason we think the 2000 vibration becomes evident before the 3150 one disappears and the wheels still slip, is that the slippage with these high friction torques will only take place under the high accelerations and decelerations of the higher frequency vibration while the wheels are virtually part of the shaft at the lower speed for the lower frequency one - at least in the middle part of the oscillation and slip only at the extreme ends of the cycle. As would be imagined with damping friction of this order the lower vibrations under load became more severe. The conclusions we are able to draw from these preliminary tests on the Phantom are summarised below :- (1) A severe vibration occurs at 3150 r.p.m. and is not appreciably reduced by the standard amount of damping. This is apparently the critical speed XXX corresponding to the three oscillations per revolution. (2) A friction torque of approx. 2625 lbs.ins. is the maximum that can be applied before another vibration at 2000 r.p.m. appears. This is about 8 times greater than the standard friction. (3) A friction torque approx. 5000 lbs.ins. transfers the vibration entirely to 2000 r.p.m. which is slightly less severe than when at 3150 r.p.m. contd :- | ||