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).
Causes of rod failure in chassis B.3-CW, attributing it to oil starvation due to a lack of crankcase baffles.
| Identifier | ExFiles\Box 88\1\ scan0224 | |
| Date | 21th February 1936 | |
| Hd.{Mr Hayward/Mr Huddy} c. Hs.{Lord Ernest Hives - Chair} BY/1/G.21.2.36. re CHASSIS NO. B.3-CW. BECKER. --------------------------------------- Hd{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister}21/HR.18.2.36. With reference to the failure of the rods on the above car, it is evident that the cost of replacement cannot be charged to the owner in this case. There appears to be two distinct causes for a failure of this type :- (a). Where baffles were not arranged in the bottom half of the crankcase, and the first 500 Bentleys turned out were in this condition, the use of the brakes on a twisty road might result in starvation of oil to No.2 and No.5 big ends, as after a serious brake application on a bend, I understand it takes as long as half a minute for the pressure to build up again. I have therefore arranged with Hs{Lord Ernest Hives - Chair}/Grys. that a Depot Sheet should be sent round arranging for baffles to be introduced into the bottom half of the crankcase as and when such cars become available. (b). There would also appear to be the possibility of this type of failure under long continued high speed conditions, although from the evidence it is clear that this does not apply to every car, as the experience of Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} in France shows that the car should stand up to this. One wonders, therefore, whether failures of this type not due to braking can be associated with rather large clearances on the rods, as under these circumstances loss of oil from 1,3, 4 and 6 would starve 2 and 5. On the large bore cars, both Bentley and 20/25, lubrication for the big ends is arranged on all bearings, so that this difficulty should be cleared up, since after the first 500 cars baffles were arranged in the bottom half of crankcase to maintain the oil supply during braking operations. BY.{R.W. Bailey - Chief Engineer} | ||