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).
Technical notes on terminals, rings, and brush materials for electrical components.
| Identifier | ExFiles\Box 50\5\ Scan142 | |
| Date | 2nd December 1922 guessed | |
| -2- "Shoetype" terminal recommended. "Pin type" bad. (flexibles). Types (1) Graphite (2) Carbon (various % of graphite)(3) Electro graphitic (carbon converted to artificial graphite in furnace) (4) Copper-graphite (various metals mixed with copper etc.) Good rings from Admiralty gun-metal. Cu.88, Sn {Mr Sanderson} 10, Zn 2. Steel and iron rings bad. Lower thermal conductivity. Contact drop 30% greater than bronze. Tarnish if left. Holders should be close to comm. for heat conductivity. Brush pressure 1½ - 2 lbs/sq.". In traction up to 6 lbs. Wear due (1) Abrasion (2) Electrolytic action (3) Burning. + (motor) brushes seem to deposit on collector. - " " " " pick up copper.(Stagger accordingly) + " " will pick up some copper due circulating current. Proud mica promotes wear due due imperfect contact. Hence abrasive brush sometimes cure wear. Use of lubricating graphite brush (no flex) contact drop higher than metallic. J.Mc.I Cater. Soft graphite wears commutators worse - wavy. Good rings from 90 cu, 8 Sn {Mr Sanderson} 2 Cu phosphuret. Lubricating brush requires flex for ionization current. Contd. | ||