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 bearing failure and the relative merits of grinding versus honing cylinder liners.
| Identifier | ExFiles\Box 130\2\ scan0315 | |
| Date | 30th November 1936 | |
| R.H.C. Typing errors in the first copy of this memo. Am Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} R.H.C. 1113 FILE KINGSBURY, Nov.30/1936. Rm{William Robotham - Chief Engineer} Noted (AHC) Re: SEIZURE OF BIG END BEARINGS. MRS. MEYER B.127.CW. This car was towed in from Keston, Kent; the mileage of the car was 34,267. Upon dismantling and examining the rod the failure was expressed due to breaking up of the metal. There was no sign of failure due to shortage of oil, and as far as is known the owner is a moderate driver. Mr. Clarke says they have only two known cases where the rod showed failure due to shortage of oil. In the memos you have sent me, a statement is made that Derby fit intermediate bearings with oil grooves when a failure has occurred. I am pointing this out because there has not been a Depot Sheet issued for Depots to do this. Kingsbury have just re-fitted new bearings to a car, but have not put the oil grooves in. Kingsbury have received copies of memos between C. and Hd{Mr Hayward/Mr Huddy}/SB{Mr Bull/Mr Bannister}, where C. states he notes that the oil grooves are fitted when convenient. Hd{Mr Hayward/Mr Huddy}/SB.{Mr Bull/Mr Bannister} has, apparently, not informed Kingsbury the details of this job. The memo from RHC.{R. H. Coverley - Production Engineer} is very interesting re cylinder liners. The two cylinder blocks I had sent down here were a good example of what is being turned out, and must have a great bearing on excessive oil consumption and rough engines. The bores were not round or true with the face of the block. The honing of the bores does not rectify the inaccuracies. The measuring apparatus used at the Works gives a false impression of the accuracy of the bore. The only true and effective way is to grind and revolve the bore. This follows the experience of a Mr. Harris who has had a lifetime experience of cylinder grinding, and who is now re-grinding Bentley bores for Kingsbury. Not only does he state that honing is wrong, but that cylinder wear can be definitely reduced by not honing. He puts forward the argument that honing leaves the walls of the cylinder on the soft side; grinding hardens the surface. He also disapproves of high polishing, his experience being that better oil consumption and better bores are obtained with the dull finish left from grinding only. The high polish has come about because it looks a better job. We are fitting the re-ground block to Mr. Ferguson's Bentley to-day. It will be interesting from a point of view of oil consumption, smoothness and cylinder wear. | ||