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).
Gear engagement thump, proposing solutions by modifying the gear ratio or motor windings.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan144 | |
| Date | 18th November 1925 | |
| EFC2/T18.11.25. -2- Contd. There has been no mechanical modification to prevent the thump on engagement due to the fact that the main power comes on too early, i.e. before the gears come completely into mesh, and this thump still exists. This has, however, been rendered a bit less serious by the fact that we have a more vigorous teazer turning of the motor. It was queried previously whether it would not be possible to make the motion of the pinion itself upon reaching the end of its travel operate the actuator box contact. At present the actuator box contact is made when the gears are only about 1/3 in mesh. The gear ratio has been altered from the original one of about 31½ to one of about 29, but in our opinion this is not a sufficient change, and this is borne out by the fact that when the motor is turning the engine we still get, though not so badly, the thumping effect due to the engine periodically running away from the motor, and the motor catching it up again. We are of the opinion that either (1) A further reduction of gear ratio is necessary. or (2) An alteration of the motor windings to heavier windings which allow the motor to take more current and have a greater acceleration (higher speed motor on same voltage). As a matter of fact, our efficiency tests on this motor also indicate that the motor would be distinctly more efficient with the heavier windings, and we feel that there would be no more current taken out of the battery per start than in the present circumstances. | ||