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).
Comparing the performance of a Lucas component with a Smith cut-out, focusing on dynamo output and battery charging characteristics.
| Identifier | WestWitteringFiles\D\March1920\ Scan38 | |
| Date | 5th March 1920 | |
| Contd. -4- It would appear that for some reason or other Messrs. Lucas have altered the winding. We are taking up this point with them immediately. The Smith cut-out on the other hand took a much smaller current to operate and especially the second cut-out sent to us. It can be judged from the volts required to operate these cut-outs both in the hot and cold condition, what portion of the dynamo out-put curve already given will be cut off due to the late cutting in point, also what portion of the negative or reverse part of the curve below the cutting in point will be effective in discharging the battery before the cutout falls away. It would appear better on the whole to make the cutting in point of the cutout slightly later than the balancing speed of the dynamo for the average temperature, as if it be made to occur exactly at the same point, what is gained is only lost at the time of cutting out by the reverse current from the battery. The point we wish to emphasize is that the balancing speed and rate of rise of cutout curves of the dynamo are the more important features and that the cutout should be made to follow what the dynamo will do in this respect. The range of the cut-out between operating and dropping away should be as small as it can be made. The figures will show that in the Lucas case this range is very much greater than in the Smith case. This we consider results to be a very bad feature, because of observations on the car Contd. | ||