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).
The merits of third brush control versus vibrator control systems in American cars.
| Identifier | ExFiles\Box 180\M2\M2.3\ img023 | |
| Date | 17th August 1920 | |
| Contd. -4- We asked Mr. Bijur what proportion of Bijur equipped American cars were supplied with third brush control machines, and what proportion with vibrator regulator voltage controlled machines. He said that three-quarters of the cars, i.e. all the smaller cars principally, were supplied with third brush control machines, the remaining quarter, principally the larger cars were supplied with vibrator control. He was very definitely of the opinion that the vibrator control system is the better of the two and made the statement that in cases of cars fitted with third brush control, at one time the majority of complaints received would be on account of over-charging, as a result of which, instructions were given to their customers to retard the position of the third brush somewhat, resulting later in a number of complaints due to under-charging. It was difficult to have one setting which would suit all types of customer, and all seasons of the day and year, whereas the vibrator control would accomplish this. The particular type of third brush regulation used was a single field winding coil connected between one main brush and one auxiliary brush, the span between the two brushes being about 120 electrical degrees, i.e. about 2/3 of the complete voltage arc on the commutator. This is different from the Lucas scheme in which a separate control winding is used connected between the main and auxiliary brushes, and the main field is connected across the main brushes. Contd. | ||