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 the various causes of vibrations and noises, particularly in relation to different chassis and 'boomy' body types.
| Identifier | ExFiles\Box 3\1\ 01-page117 | |
| Date | 2nd October 1924 guessed | |
| - 2 - running on the gears. On the third gear it is present at about 28 to 30 m.p.h. On a test recently carried out by Ex. he found that this could be affected by having slack on the splines used for attaching the front gear of the side shaft, which was also "damped". This may give you a line for your investigations. A point I certainly wish to bring home to you is the fact that this period vibration on the rears is an objectionable feature, and is more pronounced when fitted with a "boomy" type of body. (d). Vibrations appear to be set up from the tyres, known as the "Pomeroy Burton" vibration. These are noticeable in periods between 10 and 20 m.p.h. and are very objectionable when chassis fitted with "boomy" type of body. This trouble is practically eliminated by using plain smooth tyres, and is aggravated by using discs on the wheels, and close fitting wings. (e). Apart from the crashing noise from the Servo gear there are certain "grunts" set up which may not sound so objectionable on a chassis, but are certainly objectionable when a boomy type body is fitted. There are several other minor causes of vibrations and booms, such as dynamo drive, fan drive, hum from the dynamo, which are also aggravated by a boomy type body. We have also had cases where objectionable vibrations aggravated by booming bodies have been due to certain periods set up in the undershield, and the tie rods used for the frame supports, also the silencer pipe which sets up periods and vibrations at certain speeds, or under certain conditions of engine running. In fact anything on the chassis which appears to set up a sonorous noise is aggravated by Boomy type bodies. 20-HP. Chassis. Generally speaking booming troubles are not so manifest on the 20-HP as on the 40/50 HP. The following, however, are points for attention:- (a). General torque reaction vibration. This is considerably eliminated as far as [struck out text] periods are concerned. [handwritten text below line]: practically CONTD. | ||