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).
Design of an SS Valve Gear Cover, focusing on noise reduction and material choice.
| Identifier | WestWitteringFiles\T\January1929-February1929\ Scan190 | |
| Date | 25th February 1929 | |
| FROM E.{Mr Elliott - Chief Engineer} SECRET ORIGINAL E1/M25.2.29. C. to HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} SS.{S. Smith} VALVE GEAR COVER. X7060 Attached blueprints LeC.2677. & 2679. herewith shew the above arranged with the following features: (1) Three holding down studs. (2) Local cork inserts for cover to rest on. (3) Cover with curved surfaces. (4) Self forming core to inside of cover. We have shewn simple spring washers under the thumb nuts but we understand from BY.{R.W. Bailey - Chief Engineer} that noise transmitted by the studs to the cover could not be eliminated on Phantom except by using leather washers and springs at this point with the nut tightened down on the standard instead of the cover as shewn on Sch. 1101. of which we sent you a print. It would appear that the cover acts as a sounding box for the studs. This new cover may be an improvement but it is doubtful if the difference will tell. We do not want to abandon clamping the cover, and think that a lot of difference might be made by using a few stiffening ribs. There used to be a curved gearbox cover on the chassis, the drumming of which was cured by the addition of webs. [Diagram showing a curved cover with webs] WEBS There are two policies that suggest themselves, one being to stiffen the faces of the cover all over with webs, and the other to use webs near to the clamping studs only. In the latter case the idea is that the stud may transmit noise by means of the diaphragm immediately round it, and that a couple of webs across this diaphragm is all that is required. [Diagram showing a cover with webs across the stud areas] We shew both styles of webbing as suggestions but believe webbing all over would be more effective without unduly adding to the weight. Regarding the question of material we believe instructions were once sent for this cover to be tried in magnesium alloy, when the idea of making it as a pressing was abandoned. We understand that this alloy is being widely used in Germany now on a production basis, and that it makes very sound castings. Referring to the question of the middle thumb nut, the addition of a special stud means extra weight, complication, and blockage of waterway, so we have used one of the existing studs as you suggest, and find the appearance does not noticeably suffer. E.{Mr Elliott - Chief Engineer} | ||