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).
Engine sump design, comparing pressed steel versus casting and outlining the pros and cons of a modified design.
| Identifier | ExFiles\Box 111\2\ scan0250 | |
| Date | 28th September 1937 | |
| 3. are, however, numerous disadvantages in having jobs done by outside firms, amongst which are lack of direct control over quantity and quality of production, and the fact that the tools are not our own. This item is regarded asthe most serious obstacle of all to employing a pressed steel sump. Further to the above points, we h ve the likelihood of a considerably higher percentage of scrap with the casting method than with the pressing, no allowance for which has been made above, and also it may be found necessary to use horizontal baffles in which case die-casting without sand cores appears to be absolutely ruled out. (3) Type of Sump. Apoint which so far has not been considered is the possibility of modifying the design of sump to make it suitable for our own machinery. The Vauxhall and Chevrolet appear to be alone in having sumps starting from the crankshaft centre line, all the others having the top half ofcrankcase carried down below this point, and then a simple sump bolted all the way round. In our case the following advantages and disadvantages would result:- (1) A smaller sump would be employed, and one which we could probably do on our own press. The design should be evolved with this aim in view. (2) There would be no sharp corners, and fitting around bearing caps which necessitates extra tooling. These costs would, therefore, be reduced nearly 15/-. (3) The cork washer could be made in one piece eliminating objections levelled at the Vauxhall scheme. (4) The increased depth of the crankcase would give extra stiffness to the crankshaft and flywheel assembly eliminating all risk of the gyroscopic effect of the flywheel making itself felt on corners. (5) The chief disadvantage in this scheme is an increase in weight of nearly 10 lbs, which is, however, to a certain extent offset by the reduced sump weight. | ||