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 a knocking sound caused by link pin distortion and clearance issues, including test results and attempted remedies.
| Identifier | WestWitteringFiles\T\2January1929-June1929\ Scan037 | |
| Date | 19th January 1929 guessed | |
| contd :- -2- links are not very easy to make. The pin is ground a perfect fit in the eye, but when the ends of the pin are pressed outward in order to lock it on the links, the central bearing portion of the pin apparently distorts at its ends and becomes tight in the outside edges of the eye. This prevents a very satisfactory bearing being made. [Diagram Text] Tight at these points due to swaging out pin ends. The fact that the link pin in the lever has a much greater angular movement than the link pin attached to the piston is clearly shewn on our tests, as if we cut down clearances this pin always seizes first. The characteristic knock from the links is a high frequency tap about corresponding to the axle dither that we recorded on the Chronograph. The knock apparently occurs with a small amplitude of axle movement, as it can be heard on a good main road with a wavy surface. It is not necessary to run over potholes to pick it out. We tried mounting the body on rubber strips, but this did not get over the trouble. As it was not an experimental car we could not do very extensive alterations to the body. We brought up knocks on our experimental subframe car, however, by fitting wooden wedges between the sub and main frames. We tried reducing the side play in the noisy links. In a standard condition this is .014 - .018. We find we can run with only .003 side clearance without seizure of the links. contd :- | ||