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).
Modifying the Goshawk II throttle control for smoother operation on a limousine.
| Identifier | ExFiles\Box 5\4\ 04-page061 | |
| Date | 9th July 1932 | |
| V4228 To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to C.J. c. to R.{Sir Henry Royce} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} He4/LMD.9.7.32. GOSHAWK II, THROTTLE CONTROL. We tried on the limousine car arranging the controls to the latest Lec. drawing. We found that it was still very difficult to get a nice gradual opening of the throttle especially over a bumpy road. In order to improve this we altered the angle of the butterfly valve. At present, in the shut position it is 35° - we altered it so that in the shut position it was 10°. We found that this modification made all the difference and gave a nice easy control. Altering the angle of the butterfly gives one a very gradual opening and it applies equally on the foot accelerator as well as the hand control. We find on the present standard Goshawk throttle which has been reduced to 1.375" dia. (originally it was 1.500" dia.) that we obtain full power at 500 revs. with the throttle only a fifth open. This means to start away gently and smoothly, quite a fine adjustment is required on the throttle. The alteration to the angle of the throttle valve was carried out without any scrap; we took an existing valve and re-ground it - all the existing levers were used. We have examined other makes of carburettor with butterfly valves and find that they work with an angle of approx: 10 or 15°. We have not been able to find any disadvantage in reducing the angle, - the throttle still appears equally tight. We strongly recommend that we should make this modification contd:- | ||