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).
Modifications to the P.2 Starter Main Switch to address carbon lagging and contact burning issues.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan166 | |
| Date | 14th June 1930 | |
| FY. FROM E.{Mr Elliott - Chief Engineer} (FY is struck through) C. to SG.{Arthur F. Sidgreaves - MD} (struck through) C. to EFG. (struck through) C. to HS.{Lord Ernest Hives - Chair} P. 2. STARTER MAIN SWITCH. We send you herewith LeC. 2804. shewing modifications for improving the above. The main object of this scheme is to overcome the trouble at present experienced of the main copper contact burning due to the carbon lagging behind on the "make". It was first decided that the fixed carbon should be sprung so that the moving carbon being rigid would then have no tendency to lag behind. This scheme however was found to result in too much complication and inconvenience so it was decided to improve what we have by making the following 4 modifications:- (1) Carbons lightened in weight. (2) Carbon break arm lightened in weight by making in duralumin. (3) Carbon break stop nearer to carbons. (4) Carbon break spring shortened in length. These alterations should reduce the lag of the carbon both due to inertia, and to the lack of set up effect against the stop. R.{Sir Henry Royce} does not like the shape of the present copper brush and the method of treating the contact faces on the ends, which latter he thinks may result in poor contact area. LeC. 2804. shews a revised copper brush very similar to that shewn on the original LeC. drawing - 2752. in which the blades are flexible right up to the root of the brush. An improvement has been effected by using two blade stops instead of one, which enables the stop to be perfectly symmetrical with the divisions of the blade, and avoids any twisting or tipping action on the contact faces of the blades. We should be glad to know of any reason why the brush cannot be of this particular design. If found too flexible the thickness of the blades can be increased, and this should be done rather than shorten their free length. E.{Mr Elliott - Chief Engineer} Handwritten top right: x7655 Stamp: ORIGINAL. | ||