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).
The testing of an A.C. Revolution Counter, noting it reads lower than actual engine speed causing vibration and component failure.
| Identifier | ExFiles\Box 82\5\ scan0151 | |
| Date | 1st June 1937 | |
| 200a Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/IMW.{Ivan M. Waller - Head of Chateauroux} 3.B.IV. June, 1937. A.C. Revolution Counter. This instrument has been tested on the production rig and on the car, and found to be correct. Sr., the testers in France, and various people who have driven the car since returning to Derby, have commented on it appearing to read lower than the actual engine speed. When it records 4500 R.P.M., the engine vibration is alarming. A slipper wheel and a valve spring have been broken without exceeding this speed. A number of Smith's revolution counters have been drawn from stock and tried on the car for comparison, and with all of them 4500 R.P.M. was easily reached without excessive engine vibration, at speeds when the A.C. instrument showed 4200-4300 R.P.M. Rm{William Robotham - Chief Engineer}/IMW.{Ivan M. Waller - Head of Chateauroux} | ||