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).
Summary of investigations into the cutting-in speed and charging issues of the Half-Charge Dynamo Scheme for the 20/25 HP model.
| Identifier | ExFiles\Box 163\6\ img180 | |
| Date | 25th April 1932 | |
| Half-Charge Dynamo Scheme. 20/25 H.P. On April 15th PN.{Mr Northey} pointed out at W. that the cutting-in and available charge for the battery without any lamps alight, was cutting-in too late in connection with the half-charge scheme as tested on our trials car. The cutting-in occurred at about 19 m.p.h., a speed of 23 m.p.h. being required to show a charge of 3 amps. He stated that we could not possibly accept such an unsatisfactory arrangement and pointed out that the dynamo should cut in not later than 16 m.p.h. without any lamps on. Sg.{Arthur F. Sidgreaves - MD}10/E19.4.32 to Wor.{Arthur Wormald - General Works Manager} urged the importance of investigation. Hs{Lord Ernest Hives - Chair}/Wst4/AD20.4.32 recommended moving the control-brush in order to improve the cutting-in point, and that Production Tests Dept. limits be closed in to 14½ to 15 amps, machines falling below these limits to be brought up by moving the control-brush. It was also stated that most of the field resistance units in the Production Tests Dept. were found to be on the high side, probably due to stretching of the wire in winding. A recommendation was made to reduce the length in order to help the cutting-in point. Memo PN.{Mr Northey}1/WT23.4.32 quoting particulars of cutting-in from another 25 H.P. trials car - GBT-24 which cut in at 18 m.p.h. but did not commence charging until 20 m.p.h., the night position cutting-in at 12 m.p.h. and it was pointed out that generators giving these figures will gradually enable batteries to be discharged running about town all the time at speeds under 20.m.p.h. The proposal to improve the cutting-in time by further adjustment of the control brush was encouraged as being a wise step. Letter EP.{G. Eric Platford - Chief Quality Engineer}3/H22.4.32 stating that the cutting-in times complained of appeared to him to be of the standard and originally approved description, but agreeing that it was important that something should be done to improve matters. Letter from By.{R.W. Bailey - Chief Engineer} (By3/G25.4.32) pointed out that we were hedged in by limitations of the actual dynamo we have available, and that the only possibility | ||