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).
Experiments on the mechanical silencing of engines, including the use of hydraulic tappets and bonnet insulation.
| Identifier | ExFiles\Box 138\1\ scan0173 | |
| Date | 10th May 1935 | |
| To Eg. & Wor.{Arthur Wormald - General Works Manager} c.c. to E.{Mr Elliott - Chief Engineer} c.c. to By.{R.W. Bailey - Chief Engineer} c.c. to Mx.{John H Maddocks - Chief Proving Officer} c.c. to Bn.{W.O. Bentley / Mr Barrington} 1160 HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}10/KW.10.5.35. Mechanical Silence of Engines. Having succeeded in eliminating mechanical engine noise from the driving seat, we have been continuing experiments with a view to cutting out noise which is heard when the engine is idling by a spectator standing by the car. We have been using the same means as previously. We are very enthusiastic about the results obtained because they cost very little, weigh very little, and produce no mechanical complications. They are particularly valuable on the Bentley, because if we silence the valve gear by using hydraulic tappets on this car we lose a certain amount of engine efficiency. We think that the plain bonnet is a very definite asset, and will demonstrate the effect on the unit fitted with the big bore engine, which you will be trying in the immediate future. Our cooling system is so efficient on the Bentley that we believe we could actually get away with the plain bonnet in any country except the tropics. Unfortunately insulating the engine necessitates a certain amount of design work to make a good job, but in view of the fact that the big bore unit may carry us on for a considerable time on the Bentley, we think this design work is well worth undertaking. We are continuing with our timing case experiments to see whether we can silence the gears without appreciably increasing the oil temperature. Our attention was called to the double tappet cover by Cricklewood, who had a 20 HP. Hispano there fitted with this scheme. HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Att: HS{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager}11/KW.10.5.35. | ||