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).
Report investigating idler gear failures on the Phantom III, detailing test results and alternative gear materials.
| Identifier | ExFiles\Box 96\1\ scan0396 | |
| Date | 8th July 1939 | |
| 361 - c. Rm{William Robotham - Chief Engineer} c. Da{Bernard Day - Chassis Design} c. Hs{Lord Ernest Hives - Chair} c. LA{L. A. Archer} c. Hd{Mr Hayward/Mr Huddy} c. W/S-C c. Hy{Tom Haldenby - Plant Engineer}/NS{Norman Scott} Mx{John H Maddocks - Chief Proving Officer}/SB.{Mr Bull/Mr Bannister}1/MG8.7.39 IDLER GEAR FAILURES - PHANTOM III ------------------------- We have been concerned as to what we might expect in the way of idler gear failures on Phantom III cars in service, since two had failed for no apparent reason. The tests mentioned in Hy{Tom Haldenby - Plant Engineer}/SB{Mr Bull/Mr Bannister}1/G.10.6.39 have now been carried out, with the results shown in attached chart. The conclusion is that there is a vast difference as regards mechanical strength between individual gears of the same type, and it is not therefore a question of the unsuitability of a given material, but of manufacturing or material defects. For instance, one of the original gears which has already run some 30,000 miles is as good mechanically as any we have tested. The two gears which failed show consistently low readings. These tests, taken in conjunction with the evidence of many cars which have run well over 30,000 miles without failure, indicate that we need not expect an epidemic, but only occasional failure of faulty gears. The fine grain Fabroil gear which we were hoping to use for replacements has proved a disappointment from the point of view of noise. They have been tried on three cars, and have had to be taken off again. We believe this is due to the increased inertia of this type of gear resulting from its method of construction, which consists of two steel plates between which is riveted the fabric disc. There seems nothing we can do to reduce the inertia appreciably. The remaining gear tested is one manufactured by Attwater, to Drg. EXS.437/8, and is similar to the material used on Wraith which has given satisfactory results from the point of view of wear. It is even lighter than the original gear. since it has an aluminium hub on to which the fabric is moulded. Its mechanical strength is better than the fine (continued) | ||