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 testing and performance of Hall's Metal Bearings on Bentley engines.
| Identifier | ExFiles\Box 115\1\ scan0065 | |
| Date | 10th September 1936 | |
| X1020 10.9.36. Hall's Metal Bearings on Bentleys. The evidence we have from the records available of the testing so far carried out is that we have never had a bearing failure on the test bed. The hammering out of the bearings does seem to be worse now than it was during the original testing. The actual results are as follow :- (1) Dec. 1935. The first endurance engine, B-14, running with solid bearings for 50 hours. The gap measurable between the two halves of the big end was .0015", but the big end clearance was still the original .0018". (2) May 1936. After 72 hours the gap between the halves of the main bearing was .001" and the clearance .0018". (3) May 1936. B-15, 30 hours. The rear main bearing clearance had increased to .0045" and the gap between the two halves was .003". (4) B-19 unit, did 3,000 miles on the road in England, followed by 13 hours on the test bed. The maximum gap between the big end halves was .016", and the maximum diminution of metal thickness .015". Without any modifications whatever, this engine has since done 125 hours full throttle without bearing failure. Road Tests. (1) Sr's trials car after 13,000 miles is reported to have .010" clearance on the big ends and .013 on the mains. (2) B-18 in B-56-BN{W.O. Bentley / Mr Barrington}, first 4¼ litre run in France. The bearings were not solid but were steel backed. A rod failed after 11,680 miles and all the main bearings had to be replaced. | ||