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).
List of R.R. screw thread specifications, their dimensions, and standardization notes.
| Identifier | ExFiles\Box 81\2\ scan0098 | |
| Date | 22th February 1924 | |
| Oy11-E-22524 -5- February 22, 1924. R.R.Threads at 1101(cont'd.{John DeLooze - Company Secretary}) Basic size 3/4" S.A.E. 3/4 x 16 This is already S.A.E.standard and is already used by us on S.A.E.pipe unions. 15/16" .812 x 16 U.S.thread form. 7/8" .875 x 16 Do. 15/16" .937 x 16 Do. 1" 1" x 16 Do. 1-1/16" 1.062 x 16 Do. 1-1/8" 1.125 x 16 Special. U.S.form. 1.150" 1.150 x 16 U.S.thread form. 1-1/4" 1.250 x 16 Do. 1-5/16" 1.312 x 16 U.S.thread form. 1-3/8" 1.375 x 16 Do. 1-1/2" 1.500 x 16 Do. 1-5/8" 1.625 x 16 From 1-3/4" upwards all threads 16 per inch and all specified as "S.A.E.Extra fine". 1-7/8" 1.875 x 16 2" 2.000 x 16 2-1/16" 2.062 x 16 2-1/8" 2.125 x 16 2.185 2.165 x 16 2-1/4" 2.250 x 16 2-3/8" 2.375 x 16 2-1/2" 2.500 x 16 2-5/8" 2.625 x 16 2-3/4" 2.750 x 16 3.205 3.205 x 16 3-5/16" 3.312 x 16 3-3/8" 3.375 x 16 Probably eliminated at 1101. 4-1/32 4.031 x 16 4-3/8 4.375 x 16 Standard Metric Spark plug thread. [STAMPED: COPY] MO/E Oy. m.{Mr Moon / Mr Moore} Olley | ||