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).
Improving the cooling of dynamos and ignition coils by repositioning them on various models.
| Identifier | ExFiles\Box 62\3\ scan0337 | |
| Date | 2nd March 1933 | |
| (3) one third of the surface of the yoke is shrouded by a bracket formed, solid with the crankchamber casting. In later designs such as Phantom and J.3 the width of this cradle has been considerably reduced and the number of securing straps reduced to one, but with the outputs of engines having been continually pushed up with consequent effect on oil and crankcase temperatures it might be worth while to spigot mount the dynamo on the wheelcase and allow air to circulate all round the carcase. There is still of course the proximity of the exhaust pipe to the rear end of the dynamo in the case of some of our models but increased air circulation round the dynamo generally would help to counteract this effect. We propose to spigot mount a dynamo temporarily on a 20/25 chassis and obtain a comparative temperature with the standard mounting running under the same conditions. To demonstrate still further the effect of more cooling the dynamo could be temporarily mounted in a forward position on the wheelcase and driven with a belt from a double pulley on the crankshaft, one pulley driving the fan and the other the dynamo. While on the subject of the cooling of electrical apparatus it will be remembered that in the early days of the 20-HP. we moved the ignition coil from a seating on the valve rocker cover to a cooler position on the wheelcase with considerable benefit. The Phantom coil which is to some extent in contact with the heat from the cylinder head and higher up in the air stream runs hotter than the 20/25. We have got the Peregrine and J.3. coils in a position as good as the 20/25 and the Bensport of course is identical with the 20/25. E.{Mr Elliott - Chief Engineer} | ||