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 Cadillac gears with in-house gears for the Phantom III gearbox, discussing noise, chunking, and cost.
| Identifier | ExFiles\Box 94\2\ scan0156 | |
| Date | 18th January 1937 | |
| 328 See R.A.C.1/LS.291238 attached. Hs.{Lord Ernest Hives - Chair} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}4/R.18.1.37. CADILLAC GEARS- P.III GEARBOX. The original suggestion to try the coarse pitch gears came from the Experimental Dept. as a copy of American practice. In the early experimental days with very few gears to choose from, experimental boxes were quieter with Cadillac gears than R.R. gears. We suggested that 50 sets should be tried on production. After trying 12 boxes, Mx.{John H Maddocks - Chief Proving Officer} says that the slight advantages of quieter side-shafts and less 2nd speed whine were outweighed by the increased chunking. Since then the Works have been able to make R.R. gears as good for noise as the Cadillac ones. The use of Cadillac gears would effect a saving of 16/6d per car, due to the less time taken to grind the teeth. We now know that when using Cadillac gears there is not only more chunking, but also a likelihood of eventual failure of the rear end of the 2nd motion shaft, a strengthened design for which is now ready for test. From the separate report Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}5/R.18.1.37., it will be seen that the chunking can be overcome by thrust type bearings. We are of the opinion that even with R.R. gears, we ought to use these bearings to reduce chunking. In that case, we could again use Cadillac gears, and get back some of the increased cost on the bearings. We, therefore, recommend that the Cadillac gears in existence be stored until we have done further testing. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||