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).
Service procedure for Bentley engine bearings during decarbonization.
| Identifier | ExFiles\Box 146\1\ scan0150 | |
| Date | 24th December 1937 | |
| Bentley Motors (1931) Ltd. LONDON............ copy to Rm{William Robotham - Chief Engineer} (Works). Sr.IO/Crn. 24.I2.37. 1245 SWDL{Len H. Swindell} Bentley bearings. Any comments Rm{William Robotham - Chief Engineer} Coming back to the bearing question, which was discussed recently at "W", as you will remember, the position seems to have changed somewhat, owing to the fact that A.C.2 is not coming up to expectations. This being the case, we have gone over to standard Hall's metal, with a white metal No 7 main bearing. This seems quite satisfactory for the moment, but the point on which I wish to be enlightened upon is the following :- Shall we be right in stepping the liners as a general routine job when 4 I/4 litres come in for their first decarbonize at 10,000 miles - this being done without removing the engine, and then when the chassis is ready for its bottom decarbonize, which in this country is at between 18,650 and 21,750 miles - and take advantage of this to carry out the necessary modifications to the crankshaft, i.e. drill it, etc., and fit, as the case may be, white metal No 7 rear mains, and providing the others have not hammered out to a too great extent re-utilize these, or in the other cases fit new main bearings throughout. At the present time, I find that there is a tendency here to let the cars go on until they get to approximately 18,650 to 21,750 miles without doing anything to the bearings. This procedure, out in France, seems to be to be on the risky side, owing to the extreme degree of roughness registered on numerous cars, which have not yet covered the above mentioned mileage. The object, of course, is economy. As you will appreciate that doing anything to the bearings before 18,650 to 21,750 miles cannot be charged to the customers, whereas our procedure, at the same mileage, is to get a customer to pay for a bottom decarbonize. If you agree that my procedure, i.e. to take up slack in bearings without removing the engine when we decarbonize a chassis for the first time, I think that we can then say safely that we are eliminating the risk of any failure until a customer can be charged for a bottom decarbonize, at which time we can carry out all the necessary modifications......... | ||