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).
Investigation into three schemes for crankshaft balance weights for the 'China IV' engine, including a comparative table of bearing loads.
| Identifier | ExFiles\Box 103\3\ scan0039 | |
| Date | 9th March 1931 | |
| X5010 R.{Sir Henry Royce} at Le CanadelHenry Royce's French residence C. Sg.{Arthur F. Sidgreaves - MD} Wer. C. Hs.{Lord Ernest Hives - Chair} Hr. Rg{Mr Rowledge}/Tsnl/DM.{D. Munro}9.3.31. Crankshaft Balance Weights for China IV. We have investigated the three schemes for the above shown on the attached Fig.I. There are important practical limitations, which are: (1) Clearing the piston skirts at B.D.C. (2) The facings on the crankshaft must not interfere with or be interfered with by the crankpin boring bars. The last consideration rules out scheme I, therefore we favour scheme III, because full size balance weights can be got on opposite the pin all right, but not so easily when over the boring bar hole, and with scheme III only half size balance weights would be required here. There would be two kinds of webs therefore on the shaft and two sizes of balance weights to suit. Also, Scheme II has no advantage over Scheme III; the other bearings are not benefited so much. The following table shows the comparative bearing loads, assigning a value of unity to the centre bearing load on the existing standard engine at 2900 R.P.M. The same total weight of balance weight - 36 lbs. - is assumed in each case. This is only 2 1/2% of the total weight of the engine, and yet effects 37 1/2% reduction in main bearing loads and brings them 10% below those of the existing engine at 2900 R.P.M. Main Bearing: 1 & 7 2 & 6 3 & 5 4 Standard engine at 2900 R.P.M. .500 .500 .500 1.000 1931 engine at 3200 R.P.M. .725 .725 .725 1.450 " " with Scheme I. .492 .508 .508 .984 " " " " II. .506 .455 .634 .907 " " " " III. .455 .455 .455 .907 1931; Ratio Balanced loads / Unbalanced loads .625 .625 .625 .625 cont'd.{John DeLooze - Company Secretary} [Stamp] RECEIVED 10 MAR 1931 | ||