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 results of fitting new brake drums with cast-in steel back plates onto a Phantom III.
| Identifier | ExFiles\Box 120\1\ scan0269 | |
| Date | 10th May 1938 | |
| A.F.M. To RHC.{R. H. Coverley - Production Engineer} from HPS.{Horace Percy Smith - Experimental Factory Mgr} c. Rm.{William Robotham - Chief Engineer} -1028- BRAKE DRUMS WITH CAST-IN STEEL BACK PLATES. Referring to RHC{R. H. Coverley - Production Engineer}/Vs.{J. Vickers}2/JT.16.3.38., we have now completed up to the fitting stage a pair of Phantom III brake drums incorporating steel back plates, and apart from a few small blowholes in the friction surfaces these have turned out very much better than previous experiments with Bentley drums. The Phantom drums have the shaped back plates as recommended by the Foundry to counteract contraction stresses, and when inspected prior to machining there was only some .025 distortion, which is considerably less than was experienced with the flat plates used unsuccessfully on Bentley. From this it would appear that the shaped back plate does reduce distortion and it certainly facilitates machining true with the diameter, but as the detail drawing only calls for .010 machining allowance on the centre of the plate it was necessary to stretch in order to bring the distortion within the limits of machinability. The drums in question are now ready for skimming true off the hubs, but as they are suitable only for the Continental Chassis 39-EX it may be some time before it is possible to get them fitted to a car. HPS.{Horace Percy Smith - Experimental Factory Mgr} | ||