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).
Specifications for Bentley RR. 56 connecting rods, including clearances, lubrication, weight, and dimensions.
| Identifier | ExFiles\Box 85\3\ scan0062 | |
| Date | 16th October 1933 | |
| To RHC.{R. H. Coverley - Production Engineer} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} Hy.{Tom Haldenby - Plant Engineer} Bentley RR. 56 Connecting Rods. Referring to your memo RHC.{R. H. Coverley - Production Engineer}9/BE.11.10.33, the clearance proposed for the small end .0005" appears to me to be suitable but the initial assembly clearance of .00075" for the large end seems to me to be rather on the small side. However, I see no harm to erecting with this figure and running the engine carefully so as to stop it if there is any tightening up. We shall be particularly interested to know how this rod stands up as a bearing to not necessarily clean oil but with oil in the state it normally reaches in service. We think the length of the groove in the top half of the bearing for lubricating the small end could be reduced by half. With regard to the figures given on the blueprint for the weights of the big ends of the standard and the RR.56 rod, we should be glad if you would confirm that the figure for the standard rod includes the weight of the big end bush. With regard to the overall dimensions of the big end, the maximum width should be kept down to the point which enables the big end to pass through the cylinder bore. This means that the rods you have should be reduced to the extent of .1" on this dimension. E.{Mr Elliott - Chief Engineer} | ||