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 on tungsten contact points from the Tungsten Manufacturing Co. under various electrical conditions.
| Identifier | ExFiles\Box 35\6\ scan 049 | |
| Date | 25th May 1921 | |
| EFC. AA.{D. Abbot-Anderson}62. 25th May, 1921. X. 2894 - TESTS OF TUNGSTEN CONTACT POINTS (P & Q) (TUNGSTEN MANUFACTURING CO. (2)). The first set of these points has now run for 500 hours under standard conditions on the bench. They have the usual blue discolouration, the blade (+) being badly pitted and the screw having a corresponding hump. The metal surrounding the points has also turned dull. The points showed no appreciable resistance, either before or after the run, as did those taken from the Liberty distributor (see report AA.{D. Abbot-Anderson}40 21.1.21). In working, a good deal of misfiring occurred, particularly during the latter part of the run. The second pair of points (Q) by the Tungsten Manufacturing Co. have been used for the tests suggested in AA.{D. Abbot-Anderson}53, 5.4.21. A non-inductive resistance was arranged to pass a current of about 4.0 amps with 6 volts. This current was passed through the points, with the distributor running at normal speed, the operation being sparkless, with an average running current of about 2.0 amps. After 45 hours of this treatment, the points were found to be practically unaffected, the faces remaining bright, as when new. An inductive circuit was now arranged, with two R.R. ignition coil primaries in series (secondaries open) with one ballast. This circuit was connected up to the distributor, working at 6 volts, without a condenser, so that a fairly bright spark occurred at the points at each break, with an average running current of about 0.4 amp. After 45 hours, the points were found to be discoloured, but otherwise sound, the surfaces remaining flat and smooth. Finally a condenser was placed on the distributor and a supply of 200 volts a.c. was brought to the insulated terminal through a metal filament lamp. In running therefore, the condenser was alternately charged from the supply and discharged through the contacts, with an oscillatory spark. Contd. | ||