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 a starter motor operation using a solenoid with engaging and hold-on windings.
| Identifier | ExFiles\Box 62\1\ scan0295 | |
| Date | 7th February 1935 | |
| -2- Hs{Lord Ernest Hives - Chair}/Wat.7/MA.7.2.35. Cont'd.{John DeLooze - Company Secretary} (c) The pinion is engaged by a spring loaded plunger through the centre of the armature. (d) Operation of the plunger is effected by means of a solenoid mounted on the end of the motor. This solenoid has two windings, one of which is the engaging winding and the other the hold on winding. Both of these windings are parallel with each other but in series with the motor. The engaging winding will permit a relatively small current of 25 to 30 amperes to flow through the motor when operating and this will just cause the pinion to rotate slowly to ensure engagement. Once the pinion is engaged with the flywheel the further movement of the solenoid operates a pair of heavy copper contacts in series with the hold on winding and the motor, which immediately permits a heavy current to flow to turn the motor against engine torque. The hold on winding would probably consist of one turn of flat strip copper and would have a very small volt drop with a heavy current. As soon as the engine fires the reduction in torque reduces immediately the motor current and therefore the solenoid force, which allows the spring loaded pinion to return to the out of gear position. The disengaging operation, in principle, is very similar to the present sequence.motor. It is claimed therefore with this scheme that in addition to eliminating the disadvantages of the present sliding armature scheme the present starter switch is obviated its function being taken over by the engaging solenoid. A saving is thus effected in cable length which will reduce volt drop etc. An experimental motor is being rigged up to try the scheme out to prove or otherwise the above statements and a further report will be issued later. A diagram of the scheme is appended. Hs{Lord Ernest Hives - Chair}/Wat. | ||