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).
Proposed modifications to the Bensport Engine's crankshaft to increase speed.
| Identifier | ExFiles\Box 85\5\ scan0003 | |
| Date | 15th April 1932 | |
| X218 R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} Bor. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} E.7/HP.15.4.32. Bensport Engine. We have been looking into the proportions of the Peregrine crankshaft, to see what can be done to raise the speed of the major critical. With the engine as constructed we must be able to pass the big end of con rod through the cylinder bore or raise the piston and rod far enough to withdraw the pin. The latter would demand an addition of .750" to the length of the rod, and the height of the engine which is quite feasible as the rod would even then be only 1.9 strokes long. Supposing however, we said it was desired to draw the big end through the bore this would limit the crankpin to the present Peregrine diameter of 1.75", and wash out any scheme of crankshaft having less than the full number of bearings since when bearings are missed out the pin size must be increased to transmit the torsion and carry the bending. We cannot get to like the shaft with fewer bearings. The crankcase is less rigid laterally owing to the loss of diagonal staying although this is not so important with the use of counter-weights. We propose to increase the journal dia. from 2 to 2.25, and by reducing the bearing widths which are very generous on the intermediate bearings increase the Web thickness from .55 to .625. CONTINUED - | ||