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).
Bench test report on Goshawk ignition parts after a 10,000-mile endurance test.
| Identifier | ExFiles\Box 35\6\ scan 114 | |
| Date | 31th January 1924 | |
| EFC. PC.19. COPY Jan. 31st. 1924. X.2894. X.4357. BENCH TEST OF GOSHAWK IGNITION PARTS. This test was the bench equivalent of a 10,000 miles endurance test, run under standard conditions, and with a view to ascertaining the effect on the following parts:- (1) Eska tungsten contact points. (MP). (2) Standard rubbing block. (3) Standard rotor blade. (4) Steel condenser gripping spring. Originally it was intended to be a test of the tungsten points, and of the rubbing block with the cam greased every 5,000 miles, but shortly after the commencement of the run, a new rotor was fitted, and later on the condenser gripping spring exchanged for one made in steel, both of which it was decided to keep under observation. Tungsten Points. At the end of 5,750 miles slight missing occurred at the spark gaps, accompanied by flashing at the points. Sparking was O.K. on 6.5 mm. gaps at 8.0 volts with a reduction in the flashing at the points, but on returning to 12 volts, on 5.5 mm. gaps, and more so when the speed was lowered, some missing occurred, as though the points were not quite able to cope with the current. Sparking with only slight missing was maintained to the end of the test, which constitutes the best performance with tungsten points so far obtained. The points themselves have the usual hard pitted, blue-black discoloured surfaces. The actual amount of wear is small, apparently a small transference of metal only having taken place, forming two small pips on the lever point, with corresponding cavities on the screw point. Rubbing Block. The wear of the rubbing block was found to be .005", i.e. from .361" to .356. The cam was given an initial greasing, and another half way through the run. This appears to be sufficient for the cam generally, but there is a tendency for the lobes of the cam to run dry. Rotor Blade. This has run 9,350 miles. The amount of wear is about .008" and extends from the leading corner to about .150" along the periphery. The surface has been left blackened and slightly pitted. Steel condenser spring. This was fitted in time to run 6,200 miles during which no ill-effects were noticed. CAP. | ||