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).
Instructions regarding ball bearing clearances, tolerances, and fits to address noise issues.
| Identifier | ExFiles\Box 94\2\ scan0134 | |
| Date | 23th December 1936 | |
| - 2 - BY.3/G.23.12.36. Whilst I do not believe that the noise is due to the interference quoted, I am prepared to instruct the ball bearing people to supply the bearings with a running clearance of .00075. This will give a positive running clearance for any type of fit within the drawing dimensions between the shaft, housings and bearings, when the oil is warm. In addition to the foregoing, we are instructing the Works to finally grind the seating on the pinion hub where the ball bearing is located when the gear is in position on the first motion shaft. There is a further matter in which the Works can help themselves viz. that if the bearings are delivered small in the bore, i.e. with the minus tolerance, the shafts can be kept down on the plus tolerance which is quoted, so as to keep the interference fit between two and three tenths of a thousandth. We do not propose to alter any of the tolerances on our drawings, as this cannot be done without entailing easy fits between the bearings and the shaft upon which they are carried, which in turn would mean worn shafts. BY.{R.W. Bailey - Chief Engineer} By | ||