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 effects of gear selection on engine cooling performance.
| Identifier | WestWitteringFiles\L\2July1924-September1924\ Scan21 | |
| Date | 18th September 1924 | |
| R.R. 403A (40 H) (SL 42 12-7-23). J.H. D.{John DeLooze - Company Secretary} -3- EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG18.9.24. To counteract this we have the fact that the same amount of work (approx.) is done in a very much longer time on the indirect gears, giving the radiator more time to deal with the heat to be dissipated - in point of fact, almost 2½ times as long on bottom gear as on third. The nett results of this is that we are better off on the lower gear to about the same extent as when we kept the road speed constant. A summary of the test appears to be that provided the engine speed is kept down, and the fan belt is definitely tight, an advantage will be gained by using a low gear. The extent of the advantage is limited by the fact that a reasonable road speed must be maintained, and hence a very low gear cannot be used. In the above tests the benefit derived from dropping two gears and driving at 20 m.p.h. was 8°C in a hill 3½ miles long. With a very slack fan belt the results would probably be reversed. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/ACL. | ||