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).
Specification table for various types of piston rings.
| Identifier | ExFiles\Box 124\2\ scan0209 | |
| Date | 10th October 1939 guessed | |
| PISTON RINGS. *Tin plated Piece No. | Bore | Matl. | Width | Radial Thickness | Dimension of "L" Section. | Open Gap | Closed Gap | Tangen Load | Diametral Load | Cyl. Wall Pressure. | Remarks --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- EB.4737 Comp.ring. | 3.5" | 4K6 | .0937 | .120 +4 -4 | | | .008" +2 -2 | 2-2.25 lbs. | 5.3 - 5.91bs{A J. Barnes - Assistant Manager} | 12.25 - 13.8lbs" | EB.4738 "L"SECTION | 3.5" | 4K6 | .0937 | .120+4 -4 | A..060" B..050" | | .008+2 -2 | 1.093- 1.25lbs | 2.86- 3.3lbs | 6.7- 7.7lb " | EB.4739 SCRAPER | 3.5" | 1/c specn. SS.{S. Smith}91 | .177" | .30"+4 -4 | .044 | | .008+2 -2 | Min 4.25lbs Max 4.5" | 10.5- 12 lbs. | 27.6- 29.2 lbs" | 8 slots 2.75 dia cutter. "J"Section PR.1192 "L"SECTION | 3.5" | 4K6 | .0937 | .120+4 -4 | A..050" B..025" | | .008+2 -2 | 1.625- 1.825 lbs. | 4.3- 4.75 lbs. | 10- 11.1 lb" | reduced similar to Hepworth &Grandage C189 C.190 * | 3.5" | 1/c "Phorni-cast" | .0937" | Min .140" Max .150" | | .394"- .405" | .007"- .013" | Min. 4.18lbs Max. 4.9 " | 11-13 lbs. | 25.6- 30.3 lbs" | Special Exp't High pressure supplied by Hepworth & Grandage. C.189 * | 3.5" | 1/c "Phorni-cast" | .0937 | Min .140" Max .150" | B-.023" A-.048" | .394"- .405" | .007"- .013" | Min 4lbs Max 4.25 lbs. | 10- 11lbs | 24.6- 26 lb" | as above C.191 * | 3.5" | 1/c "Phorni-cast" | .177" | Min .140" Max .150" | Min .040" Max .050" | .394"- .405" | .007"- .013" | Min 4.25lbs Max 4.5lbs | 10.2- 12lbs | 27.6- 29lb " | as above Comp. EW.2172 "L" | 3.25 | 1/c. 4K6 | .0937" | .112" | | .378 Min .406 Max | .008 | 1.375- 2.11lbs | 3.625- 5.56lbs | 9-13.8 lbs" | EW.2173 PR.1170 | 3.25" | 1/c 4K6 | .0937 | .112" | A.{Mr Adams} .0565 B. .0437 | .378 Min .406 Max. | .008 | .75 - 1.24lbs | 1.26 - 3.25lbs | 4.9 - 8.1lbs" | 1. | ||