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).
Calculation of crankshaft frequency, harmonics, and resulting vibration speeds.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 46 | |
| Date | 22th April 1927 guessed | |
| contd :- -13- The frequency of the gas pressure torque consider- ing each cyl. separately is one complete cycle in two revs. or half cycle per rev. The frequency of the shaft is 9900 oscillations/min. Therefore the frequency of the crankshaft will coincide with the frequency of the first harmonic of the gas pressure torque at 9900 ÷ 1/2 = 19800 r.p.m. Synchronism of the shaft with the 6th. 9th. 12th. etc. harmonics would be expected at the following speeds. 6th. harmonic 19800/6 = 3300 r.p.m. 9th. " 19800/9 = 2200 " 12th. " 19800/12 = 1650 " 15th. " 19800/15 = 1320 " 18th. " 19800/18 = 1100 " Referring to the curve we observe that vibrations of appreciable amplitude are evident at these speeds also that the peak value of these vibrations agree very closely with the above table. Hs{Lord Ernest Hives - Chair}/A.C.Lovesey. | ||