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).
Letter to The Light Production Co. Ltd. concerning a preliminary run and dimension comparison of new pistons.
| Identifier | ExFiles\Box 86\2\ scan0216 | |
| Date | 16th June 1934 | |
| X 236 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}7/KW. 16th June, 1934. The Light Production Co.Ltd., 60/66, Rochester Row, Westminster, LONDON, S.W.1. For the attention of Mr. Brookes. Dear Sirs, We have now had a preliminary run on pistons with the new grinding. Attached is a chart showing the measured sizes of piston and measured sizes of bore when the test commenced. By comparing the piston sizes with those given with our letter of the 19th December 1933, you will see that the dimension 'I', i.e. largest diameter across the top of the skirt, is really less than half a thou. different to the previous dimension. The bottom of the skirt, dimension 'K', is from 1 1/2 to 2 thou. up on the original dimension. We ran these pistons first exactly as shown on Chart No.3, and we were down in power as you know. We honed the bores out half a thou. and gained by H.P; we honed the bores a further half thou. and gained another 2 1/4 H.P. It would therefore appear that the original clearances were absolutely the minimum that could be employed without loss of power, and there seems to be some doubt as to whether we could stand more than half a thou. taper on the skirt. | ||