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).
The unacceptable eccentricity of Bentley rear brake drums (G.100981) due to incorrect jig usage during grinding.
| Identifier | ExFiles\Box 120\1\ scan0196 | |
| Date | 29th June 1937 | |
| To RHC.{R. H. Coverley - Production Engineer} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} c. to Ws. 1028 Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}3/AP.29.6.37 BENTLEY REAR BRAKE DRUMS G.100981 The above drums are finished on a grinder and on Production run .003" or .004" eccentric on their races. This does not seem a good standard for a ground finish. Recently we wanted a dead true drum but with every care taken the Production grinder could not make one to run more true than .002" or .003". Looking into the matter we find that the hub of the drum is locating on part of the jig not meant as a location; the end of the hub is being clamped against a rough machined surface. The machine operator himself complained of this. The jig drawing HA.9866 appears to be quite in order, but the correct jigs do not appear to be in use. Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} | ||