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).
Pros and cons of deleting liners between main bearing halves.
Identifier | ExFiles\Box 115\3\ scan0136 | |
Date | 29th November 1937 | |
To RHC.{R. H. Coverley - Production Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. to Hs.{Lord Ernest Hives - Chair} c. to Ds. c. to Hd.{Mr Hayward/Mr Huddy} c. to Br.{T. E. Bellringer - Repair Manager} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}1/AP.29.11.37. MAIN BEARINGS. In reply to the memo RHC{R. H. Coverley - Production Engineer}/SB.{Mr Bull/Mr Bannister}6/MJ.15.11.37., whilst agreeing in general with regard to production advantages by deletion of liners between main bearing halves, we would make the following comments. (1) At a discussion some time ago over the same subject, Hd.{Mr Hayward/Mr Huddy} stated that in many cases where main bearings had increased their clearance through hammering or wear, he had been able to put the car again on the road for another 10,000 miles by thinning down the shims to take up the excess clearance which, as we must agree, is simple and cheap and possibly takes the car out of the guarantee periods. In similar cases, assuming there were no shims, a new set of bearings would be necessary and it is doubtful whether a good job could be made unless the engine be removed from the chassis. Furthermore, it has been proved that in our aluminium crankcases the bearing housings do distort in service which, when shims are used, can be compensated by additional 'nip'. Altogether we consider that it is not quite so simple as the paragraph in the memo would imply i.e. "merely remove the old bearings, replace with new and re-assemble." Our crankshaft wear is not so negligible that it can be disregarded and takes place not evenly, but oval. It would appear that to supply the Depots with bearings in a finished condition would necessitate them being equipped with numerous bearings of different finished dimensions. (2) As the main difficulty of producing bearings to the present system with liners appears to be the nature of the aluminium alloy bearings demanding more nip and the inability to obtain RR.56 liners at a consistent thickness, what advantage would be gained in the case of Whitemetal steel backed bearings with corresponding liners, to delete these liners and make the bearings in true halves butt faced.? We mentioned this because with the increased area given to the bearings on Wraith and Bentley III. it is quite possible that Whitemetal main bearings will stand up to the job. continued | ||