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).
Cause and potential cure for an elusive engine knock related to gudgeon pin lubrication.
| Identifier | ExFiles\Box 35\2\ scan 214 | |
| Date | 25th March 1920 | |
| x.24/48. EX MAR 25 1920 A.T. (2) RECEIVED x.y3y. H.R. from E.F. E.R. to PH. P.H. to P.W. P.W. to CK.{Mr Clark} x.2448. y.3459. EP{G. Eric Platford - Chief Quality Engineer}11/F25.3.20. RE. ELUSIVE KNOCKS. An engine was condemned on test the other day owing to it having a decidedly-bad knock which we considered was a bad sample of elusive knock, and which was demonstrated to you by Mr.Maddocks. Although we gave our usual attention to the pistons, the knock was not cured and could not be passed, but after further investigation, it was discovered that there was a shortage of oil supply to the gudgeon pin, due to the faulty fixing of the big end bearings, the top bearings being fixed in the cap, and vice versa, hence no oil-way to the gudgeon pin. On fixing the rod correctly, we found that the trouble disappeared. I bring this to your notice as I feel it may guide us in obtaining some cure for the elusive knock, as we all feel that this knock is certainly one which takes place from the gudgeon pin, it having the same general characteristics as a slack gudgeon pin. This also proves to us the fact that we might increase the lubrication of our gudgeon pins to advantage, and it has been suggested that the hole in the connecting rod could be extended or made into an annulus so that the oil feed to the gudgeon pin is increased more than it is at present. The holes in the bearing are even now not central, and do not therefore get the full bore of oil from the crankshaft. I should be glad if you will give this matter your serious consideration, as we are anxious to avoid any further cars going out on which the elusive knock we feel is sure to sooner or later develop. Is there any reason why the holes in the big ends should not be in the centre of the bearing? RP. | ||