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).
Reasons for eliminating 'Modification D' related to Bentley chassis engine bearings.
| Identifier | ExFiles\Box 114\3\ scan0049 | |
| Date | 11th October 1938 | |
| CWH. (K) BENTLEY CHASSIS - RE: BEARINGS. I recently made a recommendation to Hs.{Lord Ernest Hives - Chair} that Modification 'D' should be entirely eliminated in view of the fact that it was not technically correct. My objections to modification 'D' were :- (a). It is quite impossible to make a reasonable job of taking up slack withthe engine in position. (b). In removing sinkage effects since different bearings wear to different extents in both the upper and lower halves, the result of using modification 'D' is to push individual journals out of line with the general axis of the shaft, with the result that very high pressures are thrown on the bearings. The above criticism must not be confused with a general bowing of the shaft, as a result of stresses being released in the life of the shaft. This effect occurs in the same direction and regularly along the shaft and only introduces loads in the neighbourhood of 20 or 30 lbs. at the outside per journal. The fault referred to above can easily introduce loads of the nature of 1000 lbs. per bearing due to differences in wear between three adjacent journals. I have received Hs{Lord Ernest Hives - Chair}'s agreement to completely cut out modification 'D', the reason why this instruction has not been issued earlier was that I had ordered oil flow testing apparatus for both Paris and Derby to be made at and I wished to have the testing apparatus available before issuing the general instruction. The oil flow testing apparatus is now completed, and in future Mod. D.{John DeLooze - Company Secretary} must be eliminated from our methods of dealing with engines with bearings which showed sinkage as a result of insufficient nip in the bearings as fitted originally. A Depot Sheet will be issued covering this. In the meantime, I wish the Depots to work strictly to this instruction. In order to be able to meet the requirements of a customer, who does not find it convenient to leave his | ||