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).
Comparing the weight of the EAC engine against the 40/50 engine.
| Identifier | WestWitteringFiles\L\Jan1924-March1924\ Scan75 | |
| Date | 2nd February 1924 | |
| Important for Ido II & III R.R. 285A (100 T) (S.H. 159. 11-8-30) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 ORIGINAL SECRET Y9930 /200 TO HS.{Lord Ernest Hives - Chair} FROM E.{Mr Elliott - Chief Engineer} re. WEIGHT OF EAC. ENGINE. Copy to R.{Sir Henry Royce} SJ. WOR.{Arthur Wormald - General Works Manager} RG.{Mr Rowledge} The comparison of weights between the EAC. and 40/50 does not appear to be quite fair to the EAC. For example the EAC. is 3% larger in capacity which means about 20 lbs. on the weight of the 40/50. Then the dynamo suspension, pulleys, and belt drive weigh about 10 lbs on the 40/50 and do not appear to be included. Again we shall save another 10 lbs over the 40/50 starter motor suspension and drive because be cancel one epicyclic reduction and a chain drive etc. and use our large final gear as a flywheel. Then there is a casing round the flywheel and clutch say 10 lbs in weight which will be used for carrying the gearbox and will replace box arms and steel brackets and tubes in the frame. Thus 50 lbs can be knocked off the 122 lbs increase, leaving the amount by which the EAC. clutch and flywheel exceeds the 40/50 in weight. This shews the difficulties attending weight comparisons between different designs of engines. We should expect the EAC. crankcase to be heavier than the 40/50. It is considerably deeper (which should save weight on the cylinders) it has 7 oil feeds to main bearings as against 3, and carries a considerable part of the aforementioned flywheel and clutch case which is the gearbox support. Again it replaces the present cast steel 40/50 engine supports by two tubular feet which cancel the necessity for a cross member in the frame immediately behind the engine and save considerable weight thereby. Reckoned in lbs. per HP. developed the EAC. crankcase as weighed is appreciably lighter than the 40/50. Also the 40/50 engine is 10.lbs. per HP. as against 8.6 for the EAC. It is possible that when we weigh an assembled EAC.4. engine, clutch, and gearbox unit with suspension brackets against similar 40/50 tackle the EAC. will not come out heavy. There is another aspect of the question in-so-far that we are on the EAC. casing in all the valve gear and the flywheel clutch and starter gear. This cannot be done for nothing. If we had to do it on the 40/50 we should add to the weight of this chassis. E.{Mr Elliott - Chief Engineer} | ||