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 page detailing dynamometer test results comparing electrical and mechanical spur gear reduction systems.
| Identifier | WestWitteringFiles\D\February1920\ Scan32 | |
| Date | 1st February 1920 guessed | |
| Contd. -2- HAL/LG6.2.ED.{J. L. Edwards} will be seen from the figures that we could not measure any appreciable slip in the magnetic clutch. We then made a test on the dynamometer - running the engine at 1000 revs. full power on each different gear reduction obtained electrically. There is a selector lever in the steering wheel which gives a direct and 5 speeds below. | Engine revs. | Gear Elect: | lbs. lift at 90" radius. | Gear reduction eng: to prop: shaft | HP. | |--------------|-------------|---------------------------|------------------------------------|-------| | 1000 | direct | 97 | 1 to 1 | 26.5 | | 1000 | 5 | 125 | 1 to 1.29 | 25.0 | | 1000 | 4 | 137 | 1 to 1.34 | 26.3 | | 1000 | 3 | 145 | 1 to 1.52 | 24.4 | | 1000 | 2 | 190 | 1 to 2.79 | 17.6 | | 1000 | 1 | 215 | 1 to 4.33 | 11.5 | We could only run for a few minutes on the low gear as there was a shower of sparks coming from the generator brushes and a strong smell of burning insulation. After we had stopped we could see that in the generator the solder at the commutator bars had commenced to run. We also took a test with the engine running at 1000 revs. full power but with the low gear engaged and on direct drive electrically. | Engine revs. | Gears Elect: | Gear. | lbs. lift at 90" radius. | Gear reduction engine to prop: shaft. | HP. | |--------------|--------------|-------------------|---------------------------|---------------------------------------|------| | 1000 | direct | spur gear engaged | 208 | 1 to 2.13 | 25.5 | It will be seen by this that it is much more efficient to use a spur gear for reduction than the electrical reduction Contd. | ||