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).
Axle ratio for the Bentley 1. B.IV. 10,000 Miles Test in relation to engine over-revving and piston failure.
| Identifier | ExFiles\Box 82\1\ scan0290 | |
| Date | 29th November 1933 | |
| ✓ 4513a To Sg.{Arthur F. Sidgreaves - MD} From Hs.{Lord Ernest Hives - Chair} c. to Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} Hs.{Lord Ernest Hives - Chair}12/MJ.29.11.33. Re. Bentley 1. B.IV. 10,000 Miles Test. Replying to Sg.{Arthur F. Sidgreaves - MD}11/E28.11.33. The question of the axle ratio on the Bentley car was considered carefully before the car left. On the previous test the drivers admitted that on a number of occasions they exceeded the maximum R.P.M. of 4,500 revs. on top gear under favourable conditions. The failure of the pistons may have been partly caused by the over-revving. We had the choice of either instructing the drivers to ease the throttle so as not to exceed the revs. or to fit the 6% higher axle ratio. We chose the higher axle ratio, (1) because we are recommending this ratio for open cars and Continental cars, (2) we have completed a 10,000 miles test in France on the Standard axle and therefore thought it would be as well to run one with the higher ratio. There is nothing to prevent the engine being run up to the limiting speed on the third gear. After the 10,000 miles is completed we can arrange with Hancock that a certain mileage daily will be done around about the maximum engine revs. Our open Experimental car which was used a lot for demonstration trial runs was fitted with the higher axle ratio, also the first Bentley car which we made had this axle ratio. Hs.{Lord Ernest Hives - Chair} | ||