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 dynamometer and road testing of the Spectre All Helical Gearbox.
| Identifier | ExFiles\Box 94\1\ scan0099 | |
| Date | 21th February 1935 | |
| Ha/Gry.{Shadwell Grylls}14/KW. 21.2.35. SpectreCodename for Phantom III All Helical Gearbox. We have now completed the dynamometer testing of this gearbox. The modifications since the last test were a thickened flange on the 3rd motion shaft to N.Sch.4344, and a 2nd speed sliding piece to N.Sch.4398 to prevent 2nd gear working out of mesh. On the dynamometer we carried out - using engine oil only as the lubricant - one hour's running at full torque on top, 3rd and 2nd gears, and 50 minutes on 1st gear. After 30 minutes on 1st gear the teeth had begun to pick up. This running is in addition to the half hour already carried out on Whitmore's oil. Reverse gear was run for 1/4 hour full torque on Whitmore's oil. We are quite satisfied with the gear teeth after this test, which was half an hour more on each gear than we have carried out before on other chassis. It was noticed at the end of the run that the slack in the 3rd motion shaft rear coupling was considerable. We will report on the cause of this after the box is dismantled. We have since run the car on the road and were unable under any circumstances to cause 2nd gear to come out of mesh. The silence of 3rd gear appeared to have improved. The next box will have a higher 1st gear and increased leverage for disengaging this gear while the oil is cold, and our remaining problem will be to obtain a sufficient standard of silence. Ha/Gry.{Shadwell Grylls} | ||