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).
History and resolution of a fault causing rattling servo gears.
| Identifier | ExFiles\Box 73\1\ scan0218 | |
| Date | 31th March 1925 | |
| X9910 WCr. c. Hs.{Lord Ernest Hives - Chair} c. EB c. LW. BY7/H.{Arthur M. Hanbury - Head Complaints} 31.3.25. RE RATTLING OF SERVO GEARS. -------------------------- Referring to the attached correspondence on the above matter, it is very easy for the original conditions which governed the decisions at the time to be entirely lost sight of, and thereby an entirely wrong construction put upon the facts as they now appear. This particular fault had been repeatedly referred to by the Experimental Dept. both with R.{Sir Henry Royce} and Sales, but it was not considered serious as compared with need to get cars with FWB. into customers' hands, as it did not affect the action or reliability of the brakes. When the trials had been successfully completed and cars had been instructed, built and tested, it was then at the last moment that the question of the servo rattle was raised, and cars refused on this account alone, which brought the matter to a head at a time when it was most important to keep up deliveries to Sales. In the meantime, the Experimental Dept. and Works had never ceased to struggle with the fault, and had evolved the scheme for curing fault by means of damping arranged by means of a spider pressing on the wheel of the servo drive axially, and at a large radius. They found that a small effort only was necessary, and that a spider giving a deflection of .025 would easily cope with the trouble. In the absence of spring steel, the first spiders were made up in Mild Steel, as the deflections were well within the resilience capacities of the gauge adopted, and until we replaced the whole scheme by ground gears which we had tried out and found to be a cure, the Experimental Dept. never used any other material in the spider than Mild Steel, and never had a car develop trouble again. Immediately the design of spider was agreed to, we ordered same up in quantities in spring steel. The spiders, however, demanded tools, and the material in correct gauge was not immediately available, and in consequence I instructed Works Contd. | ||