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 a supplier clarifying manufacturing tolerances for propeller shaft universal joint components.
| Identifier | ExFiles\Box 148\4\ scan0115 | |
| Date | 12th May 1939 | |
| 1262 c. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} 12th. May 1939. Your ref. JAD.MW. BY.6/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Messrs. Hardy Spicer & Co. Ltd., Birch Road, Witton, Birmingham. 6. Dear Sirs, Propeller Shaft - Universal Joints. With reference to your letter of May 9th., this has been passed over to me for my personal attention as the whole matter of the production of the joint to the limits in question was introduced and enforced under my personal supervision. The facts of the case are, that our Works have produced the parts to the specified limits, but we have insisted on having rollers to a specified size from which they must not vary more than 1/10 of a thou. The figures quoted on your letter were those to which we were working for a period of two years. They represent limits of 1/10th of a thou. on the middle pin, and on the needle roller and bearing bush respectively. In order to give the Works a slightly wider margin I later increased the clearance as follows :- Minimum positive clearance .00025 Maximum positive clearance .00055 This gave a total sum for the limits of .0003. This limit is divided as .0001 on the pin and .0002 in the bush, the limit on the pin being minus, the limit in the bush being plus, as we invariably work to unilateral limits. Finally, to prevent misunderstanding I would confirm that we do not produce a pin and then measure the diameter of the pin, plus 2 rollers, and produce a bush to suit. Any pin and any bush produced in our Works could be used interchangeably over the whole series. | ||