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).
New design for Spherical Seated Unions, comparing dimensions and thread standards.
| Identifier | ExFiles\Box 34\2\ Scan012 | |
| Date | 5th January 1927 | |
| X.2170 To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to BJ. RG.{Mr Rowledge} c. to Hs.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} E2/M5.1.27. SPHERICAL SEATED UNIONS. We send you herewith blueprint of LeC.2360 shewing the above made to reduced dimensions and we also attach a print of LeC.2183 for comparison, shewing the existing design. Thread diameters and hexagons it does not appear possible to alter, but practically all other dimensions, and wall thicknesses, have been reduced. The leading dimension and the amount saved over LeC.2183 are shewn in the table on LeC.2360. With regard to the threads to be used, the following tables shew the threads we should naturally use (in the second column) to RR. standard, and the threads we are supposed to use on aero engine work to the A.M. standard (in the 3rd. column). THREAD DIA. RR. STD. NEW TYPE THREADS+ A.M. STANDARD. .375 24 20 .437 22 18 .5 20 16 ) A.M. threads .562 20 16 ) table II. .625 20 14 ) .687 20 20 .750 20 20 .812 20 20 .875 20 20 ) A.M. threads .937 20 20 ) table II. 1.062 20 20 1.125 20 20 ) 1.187 20 This dia. not on list ) 1.312 20 16 According to our list there are no fine threads available in the A.M. standards below .687, and in the larger dias. there is one size that we require missing e.g. 1.187. We should like to obtain the permission of the A.M. to use the second column. E.{Mr Elliott - Chief Engineer} | ||