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).
Investigation into chassis vibrations, distinguishing between those caused by engine pulsations versus road shocks.
| Identifier | ExFiles\Box 25\3\ Scan059 | |
| Date | 29th October 1919 | |
| X634 C. EP.{G. Eric Platford - Chief Quality Engineer} Bn{W.O. Bentley / Mr Barrington}13/W291019. RE CHASSIS VIBRATIONS FROM ENGINE PULSATIONS. We have your wire reading:- " Barrington Hives suspect short connecting rods increase amplitude of reaction vibration carefully compare with longer rods and equal compression ratios and filling." These points were most carefully tried by Mr. Hives quite early on in the tests of the short rods and aluminium pistons, and Mr. Hives is quite satisfied with the tests then carried out, and I am sure we are all convinced from evidence which has lately been available that the short connecting rods are not at fault. In this connection and with reference to the general situation arising from the anxiety felt by Mr. Johnson and Sales Dept. regarding chassis vibrations, I think we should tell you our experiences after the Conference yesterday: At Mr. Johnson's request Mr. Wormald and I endeavoured to the very best of our ability to appreciate the vibration referred to by Sales Dept. when sitting in the back seats of the low compression chassis, 2-LW sent down from Derby on Sunday last. It was quite impossible to perceive the difference between full acceleration and retardation, or in fact engine declutched, ticking over slowly, except by exceedingly carefully attention to small vibrations felt through the floor boards. The difficulty in perceiving these vibrations was so great that we are convinced that they are quite un-noticeable except to those who are trained in this class of work. We were later joined by Mr. Cowen, Mr. Hives and Mr. Platford. Mr. Cowen was perfectly clear regarding the vibration which had been worrying him personally. This vibration occurred under all conditions of running on average roads and these vibrations were obviously due to small road shocks. Mr. Cowen was not able to perceive the difference between full throttle and no throttle and I should not expect him to be able to do so. It was some time before we could perceive this difference ourselves. We believe that a particular class of vibration, that due to engine pulsations, has been appreciated by Sales Dept. by the more technical and perceptive members, and the importance of these vibrations has been magnified out of all proportion by other members from London appreciating the other vibrations which are obviously due to road shocks, placing the magnitude of these vibrations at the door of engine pulsations. We honestly believe that this question of engine vibrations has assumed a most hopelessly distorted form and that we shall in a few days succeed in showing London that they are mistaken in their view that the present standard low compression chassis vibrates on picking up in a manner objectionable to passengers. We do not suggest that the high compression chassis does not vibrate, but this trouble has always | ||