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).
Comparing the performance and endurance of different fan belts for the Phantom III engine.
| Identifier | ExFiles\Box 94\5\ scan0048 | |
| Date | 22th December 1937 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Std. c. RHC.{R. H. Coverley - Production Engineer} c. HS.{Lord Ernest Hives - Chair} c. By/CS. Rm{William Robotham - Chief Engineer}/Std.8/MH.{M. Huckerby}22.12.37. Further to our memo Rm{William Robotham - Chief Engineer}/Std.6/JH.27.10.37 the standardisation sheet mentioned therein was withdrawn but another one has not yet been issued. The fan and drive which we really wish to use on Ph.III is the 5 blade Cadillac fan with a 1/1 fan speed/engine speed ratio. With this ratio, up to the time of writing the above memo, we had been unable to get a fan belt to stand up to this duty. We therefore issued a sheet for the 5 blade fan with .9/1 fan speed/engine speed ratio, which is reasonably satisfactory with the British Goodrich fan belt. This drive also entailed modifications to starting handle support bracket to give clearance between it and the fan belt. As mentioned in above memo it was decided finally to attain this clearance by standardising LeC.5610 starting handle scheme. Since writing the above memo, however, we have obtained a fan belt with an entirely new construction (identical with the latest American belts) and have done a certain amount of testing with same. Running under maximum speed conditions on the test bed with the 1/1 ratio this belt has completed two hours and is entirely satisfactory. It is not stretched, broken, worn or damaged in any way, while the slip percentage at maximum speeds is only 3% - 4%. The previous belt (British Goodrich) in a similar period of running was scrapped, it very quickly stretched to the limit of its adjustment and finally broke, while the slip percentage was of the order of 10% - 20%. This test is sufficient to indicate the superiority of the new belt, but further endurance will be necessary in order to decide finally whether it is fit for production. This endurance should be completed in approximately 3 weeks time. When this is completed we will issue new sheets for the Cadillac 5 blade fan with 1/1 ratio and Ferodo made belt, also for starting handle scheme LeC.5610. One point which was noticed during the two hours endurance running was that the bellying out of the slack side of the Ferodo belt was far less than that of the British Goodrich belt, so much less that we do not think any alteration to the existing starting handle support bracket will be necessitated | ||