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).
Analysis of whitemetal compositions, issues with shims, and a report on crankshaft wear.
| Identifier | ExFiles\Box 97\1\ scan0017 | |
| Date | 15th December 1936 | |
| -7- The efforts on RR.56. are shewn on Photographs 2 & 9. A further metal which is run on to steel shells and used by G.M.C. in America is known as 14 and 14.B. is to be tried having a lead base. The complete analysis of these type of whitemetal is as follows. RR.Std. Hoyts 11.H. Hoyts Z.3. G.M.C.14. Copper 3.6% Antimony 9.3% Tin Balance. Copper 2% Antimony 9% Cadmium 2.4% Tin balance. Copper 3.2% Antimony 9% Silver 1.7% Tin Balance. Tin 5% Antimony 15% Lead balance. (5) Shims. The A.C.7. facing as applied to steel shims is not successful and in most of the 4¼ litre Bentleys which have been stripped there are signs of the facing coming away through bad adhesion on the big ends. It is also reported that Production have a considerable amount of scrap due to this fault. Although this is not the direct cause of big end bearing failure, a piece of the facing in the bearing face roughens the surface and makes the bearing more subject to seizure. Whitemetal facings are not successful in view of the high oil temperatures and soon parts company with the steel. All of our recent tests have been carried out with solid shims in RR.56. and these in the fully heat treated condition are very satisfactory without alteration to the sectional thickness when tightened up several times. These have now been standardised. (5) Crankshaft wear is confined to the main journals, the actual wear on the crankpins being negligible and approximately to .00025 - .0005 in 20 - 30000 miles. The wear registered on the main journals is not evenly distributed on the circumference but on one particular side resulting in ovality. This position is where the oil hole is drilled in the journal and taking the centre line of the hole across the faces of the journal is also the peak of the wear. This wear tapers to almost nothing at 90° either side and deserves investigation. The oil holes are arranged as follows - No.1. & 7 are in line with the throws of No.1. & 6 crankpins. No.2. & 6 are drilled midway between Nos.1 & 2 and 5 & 6 throws. contd | ||