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).
Magneto duration test which resulted in a broken rocker arm and spring, including a table of minimum firing speeds.
| Identifier | ExFiles\Box 36\1\ scan 116 | |
| Date | 15th February 1917 guessed | |
| Contd. (5) X2682 - DURATION TEST At the start of the duration test of this magneto there was no arcing at the platinum points but this developed intermittently almost immediately. The H.T. sparking was apparently quite O.K. After about 9 minutes run at 6000 R.P.M. the rocker arm broke, and the magneto was stopped. It was speed up again in order to see if it would run sufficiently O.K. to obtain the wear on the fibre, but after running a short while the rocker spring broke in three places. We are sending the broken parts to St.{Capt. P. R. Strong} Margaret's. We have another Bosch Z.A.2 magneto and will start another duration test, if required to do this. We give below some observations of minimum speeds for regular firing across various lengths of gap, taken from one of these magnetos. Gap (mm) Speed Retd. (R.P.M.) Speed Advd. (R.P.M.) 1 120 96 2 140 120 3 170 180? 4 190 200 5 230 275 6 330 350 7 400 430 8 550 550 The safety gap on this magneto is ___ mm. and the weight ___ lbs. ___ ozs. The weight of the Dixie m.c. type is 6 lbs. 8 ozs. and if the C.A.V. 6lbs. 7 ozs. EFC. | ||