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).
Standardization of dynamos and two-rate charge schemes for the 20/25 chassis.
| Identifier | ExFiles\Box 163\6\ img136 | |
| Date | 4th February 1931 | |
| X6016 Ry. from EFC. c. By/RD. EFC4/AD4.2.31. X.6003. DYNAMO FOR 20/25 CHASSIS AND TWO-RATE CHARGE SCHEME. X.6016. Referring to your By/RM{William Robotham - Chief Engineer}/W5.2.31, the latest type of 20/25 dynamo die cast commutator end bearing bracket was run on the 10,000 mile test of 18-GIV on a 48 coil high output dynamo and as we found no disadvantage of this die cast bracket we consider it suitable for standardisation and are circulating a standardisation sheet accordingly. In regard to the actual equipment for the 20/25, we recommend that we standardise pro tem the medium output 48 coil machine without a two-rate charge scheme. We think the reason for this recommendation will be fairly clear. The two-rate charge scheme was called for for use in conjunction with a high output dynamo because of the excessive charging current to the battery that would otherwise obtain. In the Phantom case we have reverted to the medium output machine for the sake of better cutting in and the output at speed is considerably reduced. We have, however, retained the two-rate charge scheme as it was already launched and there is no particular objection to it. In the 20/25 case there would appear to be no particular reason for introducing it if we adopt, as we recommend, the medium output 48 coil armature. The recommendation for this machine is precisely for the same reason as in the P.2, case namely, suitably early cutting in to give a suitable supply of current for Town running. It is therefore our intention to circulate a standardisation sheet for the medium output 48 coil armature 20/25 dynamo with the latest type of die cast commutator end bearing bracket. In regard to the control brush angle, we are arranging to run the medium output machine for the purpose of fixing upon this angle and also for the purpose of taking a 14 volt curve which we have not so far obtained on this type of machine. There appears no reason why we should not proceed with material for these dynamos. EFC. | ||