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).
The design objectives and features of SS. Invar Strut Pistons.
| Identifier | ExFiles\Box 15\3\ Scan031 | |
| Date | 27th June 1929 | |
| X7040 SECRET. BY.{R.W. Bailey - Chief Engineer} FROM E.{Mr Elliott - Chief Engineer} EB/M27.6.29. c. to Sg.{Arthur F. Sidgreaves - MD} HS.{Lord Ernest Hives - Chair} SS.{S. Smith} INVAR STRUT PISTONS. We send you herewith LeC. 2729. and 2730. shewing the above. The objects of this design are to overcome piston knocks at all temperatures and to overcome little end knocks. The piston should run with about the same clearance as cast iron pistons on the skirt. The crown also can have less clearance than we commonly use since it remains absolutely central in operation with the cylinder bore. The little end pin is put in as a push fit cold, but tightens up when hot due to the Invara not expanding with the pin. The fixing studs and nuts for the head should be made of some steel that maintains its strength with heat, such as stainless. E.{Mr Elliott - Chief Engineer} BY + FRE | ||