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).
Road test results for crankshaft vibrations on a 49-GB car.
| Identifier | ExFiles\Box 25\3\ Scan107 | |
| Date | 6th July 1923 | |
| X.634 CRANK SHAFT VIBRATIONS. 49-GB CAR. ROAD TESTS. On accelerating from 4 m.p.h. with throttle full open, vibration periods develop at the following speeds:- 8 to 11 m.p.h. 15 to 22 m.p.h. 29 to 42 m.p.h. The speeds being the duration of periods and rising to maximum intensity and falling in equal proportion as max. intensity occurs at about the mean of each period. 8 to 11 m.p.h. max. intensity 9 1/2 m.p.h. 15 to 22 " " " 18 1/2 " 29 to 42 " " " 35 " The worst period is from 15 to 22 m.p.h. - The vibrations being felt throughout the car. Crankshaft slipper wheel taken off. Period develops from 7 to 9 m.p.h. - very slight. at 19 1/2 " - slightly pronounced. at 29 " - " from 44 to 46 " - very pronounced. These periods are passed through almost immediately and probably do not have a duration of more than 25 to 50 revs. of engine, excepting the 44 to 46 period which has probably 100 revs. duration. These vibrations are probably torsional, on account of their appearing in practically even ratios of 1. 2. 3. Torque reaction periods develop at 6 to 11 m.p.h. and at speeds from 46 upwards. Slipper wheel refitted and tension on springs released, allowing wheel to be rotated quite freely. Result - very slightly better than previous. | ||