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).
Complaints of shock damper knocks and investigating the cause.
| Identifier | ExFiles\Box 151\2\ scan0358 | |
| Date | 20th January 1938 | |
| To. By & Rm. {William Robotham - Chief Engineer} From RHC {R. H. Coverley - Production Engineer} /SB. {Mr Bull/Mr Bannister} O. {Mr Oldham} to C.H. RHC {R. H. Coverley - Production Engineer} /SB. {Mr Bull/Mr Bannister} 1/MC.20.1.38. SHOCK DAMPERS. A number of complaints have recently been received from GWH. {George W. Hancock - Head Chateauroux} , regarding Shock Damper knocks, and it is claimed that cures have been effected by fitting new main bushes having the bores scraped in position to provide a close fit on the shaft. The effect of fitting new bushes and hand scraping the bores of same will, no doubt, provide a temporary cure, due to the cross-binding effect, but this does not represent sound engineering practice whereas the present process of diamond boring the bushes is the best we know for ensuring accuracy and lineability. The minimum diametral drawing clearance between shaft and bushes is .0005., the shaft being ground to a limit of -1/2 and the bush diamond bored to a limit of +1/2. giving a maximum possible clearance of .00125, but in spite of these fine clearances, cases of knocking after small mileages are still reported. It would appear that the damper assembly under designed conditions is prone to knocks, but on reviewing the number of failures it seems that some peculiar condition is present because we have failed to reproduce the knocking on a damper returned to the Works with this complaint. Since we can offer no solution by improved manufacture, further investigation seems to be necessary, in order to determine the true cause of the trouble. RHC {R. H. Coverley - Production Engineer} /S.Bannister. | ||