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).
Dynamo cutting-in speed, RPM, and the effect of third brush adjustment.
Identifier | ExFiles\Box 36\4\ scan 159 | |
Date | 25th October 1920 | |
Contd. -2- We do not agree that 15 M.P.H. is the best and lowest cutting in speed that can be obtained. With the dynamo in the cold condition and the battery at 12.4 volts, the dynamo cutting in is 610 R.P.M. corresponding to 390 R.P.M. of the engine, which corresponds to 11.7 M.P.H. As to whether the cutting in actually does take place at this point or later, depends upon the cutout. The cutouts vary in this respect, but there are cutouts which would allow the cutting in point cold on the outfit to occur at 12 M.P.H. In addition to the above we do not agree to the statement that retarding the third brush 1/4" has the desired effect of bringing the cutting in speed from 18 to 15 M.P.H. Actually this movement would reduce the m maximum output of the dynamo, but as the dynamo is not loaded on the point of cutting in, this should not affect the cutting in speed indirectly by first affecting belt slip. As a matter of fact, we have never found on the bench any variation of the position of the third brush to affect the cutting inspeed of the dynamo materially, so that in the instance cited there must have been some other change of condition which has been over-looked. W EFC. | ||