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).
Various engine issues including connecting rod and main bearing wear, and oil leaks from crankshaft fouling.
| Identifier | ExFiles\Box 146\2\ scan0247 | |
| Date | 23th June 1937 | |
| The dynamo charge indicator lamp, as you know, was not working. This is now functioning quite well. With regard to the work carried out on the engine, it all seems fairly standard. As regards N°4 con. rod rotating half an inch before the bearing moved, owing to slackness in the bearings in the con. rod housing and the remaining rods being able to be rocked over sideways, showing a barrel shaped bearing, you will be interested to hear that, whenever we take an engine down at a similar mileage (or in fact at a less mileage) we find the con. rods to be in the same condition. Therefore this did not surprise us at all. Are we to conclude that, when we dismantle engines for overoiling or other trouble and find con. rods (as we always do) in a rather anti-mechanical state, we should also change the 6 con. rods? If so, is not this going to cost the Company a lot of money? As you know, the replacement con. rods will be in exactly the same condition at the same mileage, unless the material has improved. With regard to N°4 main bearing being found to be on the tight side, this of course proves what we have always said, that this business of tightening up bearing is rather anti-mechanical, although it seems to have had some effect, inasmuch as, since we have been carrying out this method of tightening up and stepping liners, we have registered no failures apart from Mr. Michelin, which I think we can call an exception. Mr. Embiricos's car has covered 12,000 Kms. since we did the tightening up job. Does not this seem to prove that it is perhaps not necessary to give Hall's metal such large clearances as we are doing if this N°4 bearing, which was definitely tight, has stood up to its job 12,000 Kms.? Since Mr. Embiricos's car has been attended to, we have, as you know, designed a tool for measuring the amount of sinkage, so we will probably no longer get a bearing on the tight side after having carried out our job. But, as you know, this job is almost what one might call "Love's labour lost". The investigation which tends to point out that the front and rear ACME threads were fouling, causing oil leaks, seems to us to be rather obviously the result of stepping in the shims, as automatically this has a tendency to push up the crankshaft and therefore cause the oil leaks in question. This is perhaps something that needs further investigation, it being quite possible that all and sundry have overlooked this point when the stepping of shims was decided upon. | ||