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).
Letter from Negretti & Zambra suggesting a modification to a pressure gauge for more accurate cylinder compression readings.
| Identifier | ExFiles\Box 40\1\ Scan083 | |
| Date | 19th September 1924 | |
| Messrs Rolls Royce Ltd. 19. 9. 1924. The greater the distance between the platinum disc and the cylinder the longer will be the time required for the gases to pass from the cylinder to the disc, and if this distance bears an appreciable relation to the length of the stroke, you will see that it will be very difficult for the gauge to show a true reading of the maximum compression pressure. We venture to suggest that were you to do away with the large steel nipple and replace the small steel nipple by one carrying the thread you require, which would thus bring the disc 1/4" closer to the source of pressure, you would find that you obtained higher compression pressure readings than you do now, and that these would agree very closely with those shown by any other accurate indicator. We trust that this will be of assistance to you, and shall be glad to hear from you further in due course. We are, dear Sirs, Yours truly, NEGRETTI & ZAMBRA Per R.e.Ford | ||