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).
Technical analysis of piston movement, oil pressure, and ignition timing under load, including a data table.
| Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan113 | |
| Date | 16th February 1926 guessed | |
| contd :- -2- Therefore under appreciable loads, the large piston does not closely follow the movement of the small piston as sufficient effective pressure P. cannot be built up to deal with the load unless cut off gap G.{Mr Griffiths - Chief Accountant / Mr Gnapp} is considerable. When we are working near the limit of the oil relay as we are trying to do with the reduced oil pressure, this factor becomes of significance where previously it could be neglected. Amongst other things the initial ignition advance is delayed as the load does not start to lift until gap G.{Mr Griffiths - Chief Accountant / Mr Gnapp} has attained measurable dimensions. (b) Variation with speed. This can almost be accounted for by the increase in oil pressure with speed. Thus in a certain case. | R.P.M. | Load lifted MAX. | Oil Pressure. | % difference Oil pressure. | Lift. | |---|---|---|---|---| | 1000 | 50 | 13.5 | 12% | 20% | | 1500 | 60 | 15 | | | The reason for the remaining small discrepancy is somewhat obscure. Hs{Lord Ernest Hives - Chair}/W.A. Robotham. | ||