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 intermittent load test and strip examination comparing Bentley, Lucas and RR 25/30 HP machine components.
| Identifier | ExFiles\Box 142\3\ scan0354 | |
| Date | 24th September 1937 | |
| 2. Intermittent Load test - Continued. It will be seen from the attached curves that the Bentley gave the better all round performance. The much higher efficiency figure at very light loads of the Lucas, is no doubt, due to a large extent to the fact that the Bentley has a reduction gear incorporated in the motor, whereas the Lucas is without such gearing. Strip examination. The armature to flywheel ratio of the Lucas combination is slightly higher than that of the RR.25/30 HP. machine. Lucas - 16.44 to 1. R.R. - 16.02 to 1. The Lucas use a special Bendix form of drive of their own in which they use a thick disc of hard rubber, threaded over a steel sleeve, which is locked with the pinion, and the lot rammed under great pressure inside a steel barrel, which is locked with the armature shaft. Thus, the turning effort of the armature is transmitted through the rubber to the pinion by friction. A slight shock absorbing effect is obtained on engagement, but no momentary slip was apparent as obtained on the RR. machine. The brush gear is cheap both in manufacture and appearance; the construction could, however, be developed to produce a cheap and efficient job. The field system is in series parallel, which by reducing the field resistance relative to the armature tends to speed the motor up for a given torque at the expense of current consumption. It would be interesting to try out one of our machines with and without such a field system, and so obtain a figure of merit. The connections to the field coils are very simple, copper strips being used, the ends of which are looped over to take the ends of the coil, which protrude from the end just far enough for the connection to be made, the whole being soldered. The connection from the other pair of coils is carried out in a similar manner, but here the strip is looped in the middle to form a projection which fits into a slot in the end of the field terminal. This method of | ||