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 decisions for connecting rods across various engine types.
| Identifier | ExFiles\Box 103\2\ scan0171 | |
| Date | 19th November 1930 | |
| RG.{Mr Rowledge} BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} C. to - SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} ENGINE WORK - CONNECTING RODS. X.3859. X.5030. While RG.{Mr Rowledge} was here yesterday (Nov,18.) we settled the exact proportions of the new articulated rod for all Vee engines. This is almost identical with our Eagle rod which has done so well in service. The articulated rod pin is made a slow taper and requires a certain amount of fine dimension, but outside this the whole is easily understood. As in the Eagle engine the pin is pressed into position and slightly collapses due to the tight fit. It is afterwards restored to its original size by the insertion of the plugs at each end. This was the original invention in this system of fitting the articulated pin. It is assumed that the material of the articulated pin will be the manganese steel used for piston work in a hard and tough condition throughout its section. We ought however to test a nitro-hardened pin as this may be found particularly suitable for this work and the core of the nitro-hardened steel has shewn itself to be excellent against fatigue stresses. With this type of rod and the plain single rods we have decided to use the 'H' section so as to avoid having two types, but we are in hopes that for economy of manufacture we shall be able to forge these so nearly to size that there will be little machining to do on the outside, and we have arranged in all cases for the panel milling, which is necessary to get the thin web, to be done with a large dia. of cutter. With reference to the 25HP. new rod we decided to make this longer to slightly reduce the over-run vibrations, as this rod is shorter in proportion than P. 2. rod. In making this new length we have adopted in this case a plain parallel panel as requiring the least expensive machining. It has the disadvantage of leaving the big end not quite so strong for its weight. We can therefore proceed with the 25HP. new rod, the articulated rods for the F.{Mr Friese} engine (Govt. request) and R.{Sir Henry Royce} engine (Schneider) - also (Govt. request) - to be paid for by the Air Ministry, and the small rod for the P.V. 12. cyl. engine. This will enable BY's specialist to put these rods through in a group so that all the parts are to the same standard. It is assumed that the finest pitch of thread that is practical is used for the con. rod bolts, which we understand is 26 T.P.I. The bolts are of the best pattern, namely, bored up, as proved to be better than the turned down bolt because of its torsional rigidity and better spigoting, and greater length of flexibility. The nuts are to be collar nuts, the circular part with a | ||