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).
The issues and experimental work concerning bearing materials for Bentley engines.
| Identifier | ExFiles\Box 115\1\ scan0001 | |
| Date | 3rd January 1936 | |
| To Eg. & Wor.{Arthur Wormald - General Works Manager} c. to M.{Mr Moon / Mr Moore} c. to Ry. c. to Rg.{Mr Rowledge} c. to Hl. c. to RHG. X1070 Hall's Metal Bearings. As is generally known, the outstanding problem we have had to face on the big bore Bentley engine, and to a lesser extent on the big bore 20/25, has been the question of bearing materials. The first endurance running we did on the big bore Bentley showed that the main bearings would not stand up to more than about 20 hours continuous high speed full throttle work. The big ends were in a similar position, but we had available as an alternative lead bronze bearings which had successfully completed a 10,000 miles test, and which are now running on a number of customers' cars. The difficulty about lead bronze bearings is that they require extra clearance, which causes greater oil flow through the bearings and consequently increases the oil consumption. Mr. Geoffrey Smith's car is a case where this has happened. We therefore were endeavouring to find a substitute for lead bronze which could be run with less clearance, and also a substitute for white metal main bearings. The first bearing material submitted by Hl. as the result of a good deal of experimental work was the tin-aluminium alloy used in steel shells as is the present white metal. We ran 200 hours on these bearings and found that, though if satisfactorily manufactured in the first place they had a good life, it was impossible to guarantee a good bearing because the adhesion was likely to break down with running. Furthermore, the production of these bearings was so difficult that the scrap frequently was as high as 20%. It was then thought that the adhesion could be improved by altering the shell of the bearing. A large number of further tests were made which proved that the production of bearings on these lines was not a commercial proposition. 200 hours full throttle, 4000 revs. and over on test bench. 15,000 miles on road, during which various failures occurred. | ||