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).
Report page detailing the conclusions and further investigation points from vehicle noise and vibration testing.
| Identifier | ExFiles\Box 154a\4\ scan0104 | |
| Date | 15th March 1939 guessed | |
| - 3 - different records, which is fairly satisfactory. The microphone results were less satisfactory since the instrument was insensitive to such low frequencies as 15 cycles/sec. The higher frequencies in the wave form were therefore grossly over-accentuated. Its performance was not constant, but this was corrected for by taking repeat readings on each occasion with the standard condition. CONCLUSIONS. There is no doubt that the vibration and noise are much reduced by increased flexibility in the torque arm mounting. The steering tubes make little difference to the vibration except for one small peak on the waveform which is apparently absent when they are removed. It was noticeable that when there was no rubber on the yoke the amplitude was about the same as with the normal suspension, but the decay, both with sound and vibration was much more rapid. On the road it appeared that the sound was less noticeable to the ear, this probably being due to the short duration. This suggests that a good combination might result if the rubber on the yoke were removed, but damping provided on the torque arm. The low figures for the Bentley 2 were probably due to the considerable fore and aft freedom of the suspension. The accelerations on the vibration waveform were lower giving less shock to the frame which may account for the marked decrease in noise. FURTHER INVESTIGATION. There is no doubt that the artificial conditions of the tests cannot be so satisfactory as measurements on the road. It will be possible for road work to be carried out when a motor converter working from the car batteries giving 200 v. {VIENNA} (A.C.) is available. Alternatively experiments could be made on the skid track at Sinfin using a length of flexible cable to the car from the adjacent R.A.F. School where electricity is available. | ||