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).
Description of the operation of Circuit 4, the 'Hold Off' (Green) circuit, including resistance, voltage, and current specifications.
| Identifier | ExFiles\Box 64\3\ scan0108 | |
| Date | 2nd May 1927 guessed | |
| -4- Contd. Circuit 4. HOLD OFF. (Green). Immediately the main current circuit is made and the relay switch pulled over, circuit 1 is broken and circuit 4 is made. Circuit 4 supplies a current through the push button switch to the bottom contacts of the relay switch and through the fine wire coil of the relay switch to earth. The resistance of this fine wire coil is 3.03 ohms. The current through it at 11.0 volts is 3.63 amperes. AT 11 VOLTS. The condition of correct operation as regards this circuit is that a current of 3.0 amperes through its coil must easily be capable of holding the relay switch lever down unassisted by the main current coil, the main current being switched off so soon as the engine by throwing the pinion out of engagement switches off the pinion operated switch and causes the electromagnetic main switch to be opened. EFC. | ||