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 performance and issues with different types of metal bearings, comparing Halls metal, white metal, and lead bronze.
| Identifier | ExFiles\Box 146\3\ scan0178 | |
| Date | 16th November 1936 | |
| - 2 - This phenomena is particularly apparent in the rear main bearing, which is held in a lateral position by the flanges on the sides of the housings, but is not limited, except by the distance pieces, in its rotary movement. We believe that if this rear main bearing were held by a dowel pin, in addition to the other six main bearings, and grub-screwed, it would have less tendancy to hammer, on condition, of course, that the grub-screw were tightly adjusted in the bearing. From sundry data we have been able to obtain from different 3 1/2 and 4 1/4 litre Bentleys, fitted with Halls metal bearings, we are of the opinion that both main bearings, and crankshaft bearings, should be changed on cars which are driven fairly severely - which is the case with most cars on the Continent. This change-over should be effected after about 25,000 kms. Results with white metal bearings appear to us to be satisfactory. CONCLUSIONS: The use of Halls metal is very costly, due to the continual change-over of the bearings. Halls metal, so far, has not shewn proper resistance to compression, to permit its use without being supported by a steel shell. The use of Halls metal wears out the housings, due to hammering - principally on the upper half of the crankcase, which will bring about future difficulties in the boring out of the crankshaft bearings (the housings of the principal main bearings are used as supports for the boring bar). Use of white metal presents no danger to the crankshaft bearings, but it does to the intermediary bearings. The metal in the intermediary bearings is very often cracked, but no immediate danger results. Whilst awaiting a more satisfactory solution regarding Halls metal, a combination, such as white metal for the mains (especially the rear main) and Halls metal for the intermediary bearings, could give better service, thus eliminating the danger of oil leaks, which consequently cause the metal to crack. :/ With new conrods (oil grooves milled out) the use of white metal might give longer life than the old type conrods and bearings. The use of lead bronze bearings in the conrods is the only method which has really given satisfaction. :/ It will be remembered that we are testing B.60 GA to elucidate this point. | ||