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).
Modifications for the G.4 engine crankcase and 4-point mounting.
| Identifier | ExFiles\Box 15\3\ Scan029 | |
| Date | 23th April 1929 | |
| X7040 SECRET R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} HS.{Lord Ernest Hives - Chair} EV.{Ivan Evernden - coachwork} G.4. ENGINE - CRANKCASE FOR 4 POINT MOUNTING ETC. E4/M23.4.29. X5000 Y5005 Referring to the 4 point mounting on the G.4. crank-chamber we had come to the same conclusion as yourself that inserted tubes for the arms were not good enough, and we had started to alter to box feet, making the necessary sacrifice in the length of the mounting. We have the schemes for this practically complete, but there are afew details still being settled up with respect to where the feet come up against the various accessories along the sides of the engine. As we shall require a new set of patterns for this crankcase we are including as many of the SS.{S. Smith} moves as possible in our schemes as follows :- (1) Split in crankchamber below crank centre. (2) Let-in duralumin main bearing caps. (3) Studs instead of bolts for main bearing except for No.4. the central bearing. (4) Studs for holding on cylinders with no nuts under. (5) Oil gallery pipe in lower half instead of top half. (6) Rear end fixing of bottom half. These modifications in particular save weight and work, as also the short intermediate cylinder studs proposed for the larger boreand the aluminium head. Whether the crankchamber face should be brought lower to improve the piston cooling is an open question. Another point requiring attention is that Derby are asking for two oil pressures on the 'twenty' as they are no longer satisfied with the relief oil for lubricating the valve rocker gear. We therefore suggest that a two valve relief oil unit should be carried on the crankcase in the SS.{S. Smith} position. Whilewe are on the job it might be possible to incorporate the scheme for running the camshaft and tappets immersed in oil. E.{Mr Elliott - Chief Engineer} | ||