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).
Improvements and fault analysis for various electrical components, including dynamos and starter switches.
| Identifier | ExFiles\Box 51\2\ Scan142 | |
| Date | 31th August 1923 | |
| Ltd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 4/T31.8.23. (b) DYNAMOS. Experiments on the commutation of 20 H.P. dynamos have been more or less continuously in progress and the commutation of machines now on production should be superior to that of the first few machines, on account of :- (1) Improved position of main brushes (found by careful experiments in this Dept.) (2) Removal of the copper coating from the brushes, enabling them to be a more accurate fit in the brush holders. (3) Better dimensions of brushes. (4) More reliable spring pressure and freedom from springs catching on stud heads brush holders. (5) Reduction of production specification of output by 1 ampere. (6) More careful bedding of the brushes. Our own experimental work shows that the commutation of dynamos with these items right is ordinarily satisfactory. In addition to the above, experiments are in progress of comparative commutation with different grades of brushes. (c) CUTOUT & DISTRIBUTION BOX. Steps are being taken in the nature of a warning plate to be affixed to battery box and generator to avoid failure of cutout due to dynamo being run with battery disconnected. Connection faults on the distribution box should be overcome by the fixing of the spring washers. The contact points have been improved by the substitution of gold-silver alloy for silver. Electrically, the cutout and distribution box will not, as we have proved, fail when subjected to intensive test, provided it is first right mechanically. (d) WIRING CONNECTIONS. These have been dealt with by the D.O. and improvements have been effected. (e) STARTER SWITCH CONTACTS BURNING. This has largely been due to the absence of oil in the switches. An instruction from us that the floating plunger should break first on the outer contacts should also improve the switch as regards this point. We are satisfied that with the switch properly constructed and filled with oil, there will be no burning of the contacts. (f) FAILURE DUE TO INCORRECT PROCEDURE WHEN CHANGING OVER FROM BATTERY TO MAGNETO IGNITION. This we think will be entirely prevented. | ||