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).
Comparison of the auto exit charge control switch against the Midgley auto switch, listing its advantages.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan042 | |
| Date | 3rd June 1927 guessed | |
| -4- Contd. The use of the R.R. type of auto exit charge control switch is an advantage over the type represented by the Midgley auto switch because:- (11) It dispenses with the series coil. (12) It dispenses with the necessity of spring supported switch contacts, i.e. it enables rigid contacts to be used. (13) It enables, for reasons previously given, a much larger relative resistance to be inserted in series with the field winding on the opening of the switch contacts, without running into vibrator regulator trouble on the one hand, or, having overcome this, a low frequency vibration of both the auto switch and the cutout simultaneously on the other, thus bringing about a much greater reduction in the charge, in fact practically switching off the charge altogether. (14) It acts not only as an auto charge controller but as a powerful protector of the system against open connections or faults in the dynamo-battery circuit between the charging switch and the chassis frame. For instance, on open battery circuit the R.R. auto switch will give in the daytime an audible warning of such a condition, and at night both an audible and a visible warning of that condition, without doing any harm to any of the circuits or apparatus. This is the only condition where the contact points are called upon for serious duty. (15) The frequency with which the contact points have to open and separate in normal running is considerably less (owing to the shunt coil being connected on the battery side of the cutout instead of on the dynamo side). The contacts do not have to open and close on slowing down and accelerating as they do in the other case. The duty of the points and also the wear of the dynamo brushes (see 132 below) is therefore reduced. Contd. | ||