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).
Procedure for creating an engine indicator diagram using an epicyclic case and pressure gauge readings.
| Identifier | ExFiles\Box 79\3\ scan0002 | |
| Date | 15th February 1916 | |
| R.R. 235 A (400 T) (S.C. 538. 15-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546. -2- E3/G17317 Contd. epicyclic case, and let it make .5 revolution against a pawl mechanism, it will move the timing of the indicator valve with relation to the engine by a certain definite part of the circle. e.g. 1/24 This 1/24 turn represents on our indicator diagram the distance between two of the ordinates. When the apparatus is running we should take a reading on the pressure gauge for one position of the valve with relation to the engine, and then slip the epicyclic case one [Half written above] revolution and take a fresh reading on the pressure gauge and so on, until we have taken a reading for all the ordinates in two revolutions, corresponding to a full gas cycle in the engine cylinder. The valve is to be one in which the passages are staggered, this being a better form than the onw shewn in the sketch Lec.743 The indicator diagram when plotted on prepared sheets should be 6". long with a pressure scale in proportion to the length of the base line, so as to give a nicely shaped diagram. We shall require a battery of gauges to cover the whole range of pressure necessary, possibly four might be sufficient. I have already discussed with you the lines which the oil pump should follow. I illustrate this in the following sketch - | ||