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).
Technical memorandum detailing the evolution and changes made to the connecting rod big end lubrication system.
| Identifier | ExFiles\Box 132\2\ scan0267 | |
| Date | 24th June 1941 | |
| Hs.{Lord Ernest Hives - Chair} from BY.{R.W. Bailey - Chief Engineer} Sg.{Arthur F. Sidgreaves - MD} RE CONNECTING ROD BIG END LUBRICATION Referring to H.2/HP.20.6.41; there is, of course, no doubt that E.I suggested two holes per crankpin, but when the tests were run in the Experimental the suggestions were turned down as being of no value - in other words, it did not save the engine. This did not mean that two holes per pin was wrong, but it was allowed to drop, and it is this aspect of the matter that was wrong. In regard to the Bentley car, nothing that was done on the lubrication was the result of this suggestion. When I took over the car side I found that we had one hole per journal to supply the oil to the interior of the crank, and one hole per pin to lubricate the big end. The 3½ litre had complete grooves on front centre and rear main bearings, no grooves whatsoever to intermediates, but there was continuous drilling - that is, you could pour oil in one end of the crank and run it out at the other so far as the journals were concerned. The first change was:- (a) Grooves following two thirds of the circumference were introduced on the intermediate pins on the 4¼. (b) The intermediate main grooves were made continuous (this was in February 1937) and their areas increased. (c) Realising that we required more oil under these conditions, an increased capacity oil pump was introduced. (d) At the same time as the larger pump was introduced, two holes per crank journal were used to pass the oil into the interior of the crank. (e) Two holes instead of one were introduced in each crankpin. (f) Finally, as experiments showed that pins 2 and 5 were still down on oil supply, three holes instead of two were used on each intermediate journal, from which these pins were supplied. It will therefore be seen that the question of overcoming | ||