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).
Continued report correcting previous findings on the starter motor's solenoid and auxiliary coil operation.
| Identifier | WestWitteringFiles\J\January1923\ Scan13 | |
| Date | 3rd January 1923 | |
| Contd. -7- EFCL/T3.1.23. rotation of the machine can be readily changed by reversing the field current connections, will be noted. Such a system also applies to the reversal of rotation direction in the starter motor. With regard to the starter motor operation our previous report EFCL/T20.12.22 needs modifying in one respect. It was there stated that "There is an auxiliary coil on the solenoid taking a small current in an opposing direction at the full voltage of the battery." This statement was based upon the Bosch diagram in which the windings of the coils shown were misleading. It has now been verified that the two coils on the solenoid operate in the same direction with roughly speaking the same number of turns, but the ampere turns of the auxiliary coil (of much higher resistance) are very much less. It is now supposed that the intention is that if the push button be held on contact unnecessarily long during the starting operation, the drop off of the main switch shall occur by the switching off of the supply current to the solenoid by the operation of the dynamo cutout when the speed of the engine is sufficient. Even then it does not seem easy to give an exact reason for the existence of the auxiliary coil on the solenoid. The main starter switch contacts do not appear to be very liberal in contact area and one would thinks some trouble might be experienced from this. | ||