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 reduce crankshaft vibrations by adjusting damping torque and friction on slipper wheels.
| Identifier | ExFiles\Box 25\3\ Scan140 | |
| Date | 20th September 1926 guessed | |
| contd :- -2- The slipper wheels were replaced with a normal damping torque of 315 lbs.ins. which, although smoothing out the lower speed vibrations, seemed to have little or no effect on the one at 3150 r.p.m. The next step was to increase the friction torque to the optimum value with regard to effective damping before it was sufficiently high for the wheels to become virtually part of the crankshaft and by raising its inertia so reduce the critical speed. We found however that with increased damping there was no clearly defined point where the critical speed changed to a lower value due to the addition of inertia to the front end. Increased friction torque on the slipper wheels was accompanied by reduction in the severeness of the vibration at 3150 r.p.m. and at the same time the appearance and growth of a vibration at 2000 r.p.m. With the slipper wheels clamped solid so that no slip occurred the 3150 r.p.m. vibration disappeared and gave place to the one at 2000 r.p.m. which was now at a maximum but apparently less intense than the higher one due to no doubt the inertia impulses being less severe at this lower speed. The damping friction of the slipper wheels just previous to the point where the 2000 r.p.m. vibration could be detected was 2625 lbs.ins. With 3200 lbs.ins. both the higher and lower vibrations were evident although the slipper wheels were found to have slipped under the influence of each vibration. A friction torque of approx. 5000 lbs.ins. had to used before the wheels became effectively solid. We can only give approximate contd :- | ||