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).
Difficulties and limitations of increasing the dynamo output on a 20/25 HP chassis.
| Identifier | ExFiles\Box 60\4\ Scan154 | |
| Date | 25th April 1932 | |
| WST WOR{Arthur Wormald - General Works Manager} c. Mr. Hx. c. EP.{G. Eric Platford - Chief Quality Engineer} c. Hs{Lord Ernest Hives - Chair}/Wst. c. Er X6097 BY.3/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 25.4.32. 20/25 HP. CHASSIS - DYNAMO. Referring to EP.{G. Eric Platford - Chief Quality Engineer}3/H.22.4.32. and Sg.{Arthur F. Sidgreaves - MD}10/19.4.32. the position in regard to the 20/25 HP. dynamo is admittedly critical and difficult. In the dynamo system which we have just abandoned without the half charge scheme the maximum output we were able to obtain with safety was 9 amps., and none of our investigations, which we have carried out, have provided us with information which would enable us to modify the original system without the half charge in such a way as to increase this output. The maximum of 9 amps. was found to be inadequate. We were therefore driven to the half charge system with the object of balancing the lamp and ignition load completely. In the half charge system we are able to obtain a maximum of 11½ amps. under precisely the same conditions of safety as had obtained with 9 amps in the original scheme. This position is obtainable owing to the fact that the full output is not on unless some of the lamp load is in circuit. We obtain a maximum of 9½ amps on the daylight running position with no load. 1½ amps. of this is absorbed by the ignition. We are therefore, without making an entire change to either the magnetic system or the armature, unable to permit with safety a greater output in the daylight running position than 9½ amps. Further we cannot obtain an earlier cutting in position for daylight running without at the same time increasing the maximum output, which would result in the armature being too hot and the solder melting. It is, however, possible to give an improved cutting in position for daylight running at the expense of the maximum output when the headlamps are in circuit. This, however, forces us back into the untenable position that | ||