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).
Test report page detailing performance, short circuit, and utility tests conducted on a magneto component.
| Identifier | ExFiles\Box 49\5\ Scan231 | |
| Date | 4th May 1921 | |
| H.H. & Co. (100 T) S.H. 768. 10-12-20) G. {Mr Griffiths - Chief Accountant / Mr Gnapp} 2947 Contd. -3- EFC {E. Fowler Clarke - Electrical Engineer} 4/T4.5.21. fairly heavy tracking of the contact breaker earthing brush. The contact points were slightly blackened round the edge. After the bearing had been used the tests were continued. (8) & (9) The open circuit volt speed and short circuit ampere speed curves of the magneto primary are similar to those of the Conner, given under cover of our EFC {E. Fowler Clarke - Electrical Engineer} 8/T31321, but rising a little more rapidly, hence both the amperes and volts at given speeds are rather greater than those of the U.S.A. Bosch Z.R.6 magneto. Reference to paragraph 16 below will show that the low sparking speeds are relatively good. (10) The test in which the magneto is run at 1500 r.p.m. for half a minute, with timing lever central, and secondary winding short-circuited, went through O.K. (11) The open circuit test in which the magneto was again run at 1500 r.p.m. for half a minute with timing lever central, and with the H.T. terminal not connected to anything, so that the secondary spark took place on the safety gap of the magneto was also O.K. (12) The short test at 1500 r.p.m. for 15 mins. with timing lever central, and the discharges taking place on 5.5 mm. gaps in air, with standard length (2 ft) H.T. cable as usual, was now made to see if the machine was normally correct after open circuit test. It was found to be O.K. (13) Utility Test. Max gaps obtained were as follows :- (a) 8.5 mm. (b) 8.5 mm. (c) 8.0 mm. (d) 7.0 mm. These compare very favourably with the results of the Z.R.6. (14) A range of advance and retard was now arrived at as described in our EFC {E. Fowler Clarke - Electrical Engineer} 4/T3.2.21. As the minimum sparking speed was obtained at the advanced position, our range was so chosen that our advance coincided with the maker's, which resulted in our retard being 1° earlier than the makers. Further advance could not be obtained on account of the irregular sparking which occurred at high speeds. Contd. | ||