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).
Big end failures on the 4 1/4 litre Bentley engine and a proposed modification to the oil supply system.
| Identifier | ExFiles\Box 115\3\ scan0206 | |
| Date | 14th March 1938 | |
| 1020 c. Hd{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister} c. Rm.{William Robotham - Chief Engineer} c. RHG. c. Hs{Lord Ernest Hives - Chair}/LS. SWDL{Len H. Swindell} BY.13/G.14.3.38. 4 1/4 LITRE BENTLEY. RE: FAILURES OF BIG ENDS. With reference to Hd.{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister}23/H.8.3.38. which after pointing out that we have had nine cases of wrecked engines on the 4 1/4 litre cars, involving a total expense of just over £1000, goes on to make a recommendation that we should deal with the cars in question i.e. the 4 1/4 to which large oil pumps were not fitted by arranging to drill an extra hole in No.2 and No.5 crankpins respectively, but otherwise leaving the oil arrangements as they are. This has been agreed to in principle, but Hs.{Lord Ernest Hives - Chair} expressed the opinion that there may be some difficulty in introducing the tools, in the meantime he has asked me to instruct the necessary tools to be made so that the scheme can be tried out, as if it is workable, as I think it will be, it will mean a considerable saving in making a sufficient change to prevent serious failure as in the nine cases referred to. The essential point of Hd{Mr Hayward/Mr Huddy}/SB{Mr Bull/Mr Bannister}'s suggestion is that if the cranks were examined, it would be observed that all crankpins 2 and 5 draw their supplies for two intermediate bearings, whereas all the pins have a long bearing as well as an intermediate and thus you get their oil supply more safeguarded when wear takes place on the intermediate bearings, and it is the intermediate bearings that wear most, therefore if we had the large oil pump and add an extra hole on the crankpin we will bring the lubrication to such a stage that the two pins in question will be comparable with the other four when wear takes place on the main bearings. BY.{R.W. Bailey - Chief Engineer} | ||