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).
Issues with porcelain insulators for ballast resistance and the proposed alternative of soap stone.
| Identifier | ExFiles\Box 24\2\ Scan114 | |
| Date | 11th March 1921 | |
| R.R. 285A. (59 T)(S.H. 986. 19-8-21.) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 3098 X 1109 Wor.{Arthur Wormald - General Works Manager} from BY.{R.W. Bailey - Chief Engineer} BY14-P11.3.21. X.3716 RE INSULATORS IN BALLAST RESISTANCE. X.1109. The insulator as at present, of course, being produced in porcelain, but a fair percentage of these are cracking in service after delivery, and this is the result of our inability to obtain porcelain piece accurately produced, as the glazing always throws the two faces, against which we tighten up, out of truth, more or less. In view of the difficulty, and knowing that soap stone is used under similar conditions, I suggested obtaining samples, in order to try how it would machine up, and also how it would withstand heat. My previous experience with soap stone, which I have actually used, was that it machined quite easily. I do not propose to depart from the standard material we are at present using, but if the soap stone was a reasonable proposition I propose to suggest to Mr. Royce that we might change from porcelain to soap stone. The use of porcelain in our Ballast Resistance is absolutely different from the use of porcelain in the sparking plug. In the latter the porcelain is fairly bulky and does not contain holes, whilst it butts up against soft abutments. All of these features are impossible in the ballast resistance, but I would like to have particulars of the porcelain Hs.{Lord Ernest Hives - Chair} refers to, and where to obtain same, when we will at once submit drawing of our insulator and ask for samples. 'We do not feel that the trouble we have had so far with the porcelain insulators demands a change of design in view of the percentage of failures, but we will put the matter up to Mr. Royce for his consideration from the point of view of modifying the design, but it will, of course, be understood that to modify the insulator will modify the whole of the pieces, which represent the ballast resistance, as a unit, except possibly the bracket fixing it to the dash.' BY.{R.W. Bailey - Chief Engineer} Mr. Hives. Whet think you ? Wor.{Arthur Wormald - General Works Manager} | ||