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).
Fitting instructions and modifications for a metal piston relay, including a diagram for a new collar.
| Identifier | ExFiles\Box 65\1\ scan0190 | |
| Date | 12th December 1926 | |
| To BY: from Hs{Lord Ernest Hives - Chair}/Ra. c.c to Sft.{Mr Swift} c. to Hbx. X7685 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}6/LG30.12.26. METAL PISTON RELAY TO LeC.2242. There are several points to notice in bringing the new relay into production. The metal piston rings require very careful fitting. They should be fitted on the steel V.{VIENNA} ring E.74983 which, when expanded, gives a size of .002" larger than the cylinder bore, and should be lapped in until their faces shew a satisfactory bedding all round. At this point the piston should just slip down the cyl. bore under its own weight when lubricated with thin oil. There is no doubt that these rings will be very difficult to manufacture satisfactorily. In order to get an easy setting for the inner piston E.74938 we should be obliged if you would arrange to put a small collar in the neck of this piston as indicated in the attached sketch. The correct setting is then to bring the top of the collar level with the top of the outer piston when the engine is at rest with no oil pressure. When the oil pressure rises, this should then give 2° initial advance. The adjusting washers E.73126 etc. and cap E.72495 should be arranged to allow lever contd :- [Blueprint Diagram Text] .025" .065" COLLAR DIMENSIONS OF COLLAR TO BE INSERTED IN TOP OF INNER RELAY PISTON | ||