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 considerations for engine components like sump joints, con-rod crank ratios, and pistons.
| Identifier | ExFiles\Box 127\4\ scan0081 | |
| Date | 28th September 1937 | |
| -2- (2) Position of Crankcase Sump Joint. We asked Taub where he would make the sump joint on his engine if he were starting with a clean sheet of paper to-day, and did not have to consider economy above everything else. He replied that he would not follow the present Chevrolet practice but would bring the crankcase below the centre line of the crankshaft as on the Oldsmobile engine. In view of this fact, we recommend that we follow the same lines on the Phoenix, in spite of the fact that it will mean 12 lbs more cast iron in the engine. We are circulating a second memo on the subject, which covers the question of the sump construction in detail. From the production point of view we do not think that too much trouble can be taken on cost analysis of various types of design, because otherwise the Design Dept. are likely to be misled. (3) Con. Rod Crank Ratio. Taub stated that he would not go below 1 3/4 con. rod crank ratio purely from the point of view of side thrust on the bore which increases the tendency to scuff. (4) Piston Design. Taub is not very enthusiastic about the new autothermic piston, but admits that other people are having success with it. Vauxhalls are actually going to B.H.P. pistons on the 25 h.p., but they cannot give any definite reason for their move at present. Taub is now recommending four rings as being necessary to obtain good oil control, and curiously enough has become an advocate of the 'L' shaped ring. About 12 months ago, when we discussed the 'L' shaped ring with him, he condemned it in no uncertain terms. We understand that the 'L' section is being taken up whole-heartedly by the American Automobile Industry. | ||