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).
Changes to crank drawing RE.869, cost-saving measures, and problems concerning the crankshaft damper.
| Identifier | ExFiles\Box 124\2\ scan0201 | |
| Date | 5th July 1940 | |
| -3- Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}4/JMS.5.7.40. As a result of memo Rm{William Robotham - Chief Engineer}/OTS.17/ML.25.4.40, the detail drawing RE.869 was produced which included: (a) Integral balance weights. (b) Minimum machining. (c) "Welch" plugs instead of oilers. (d) Material: Spec.2052. (e) Brinell 241-269. (f) Nose to suit Humber Damper. (g) Heat treatment in the forging state (machining to be continuous). Note. Referring to the memo above which instructed this crank to the shop; It was realized that integral balance weights would mean sinking a new die. Therefore, the justification for this would be forthcoming by applying the remaining points (above) to existing crank forgings. Also, it was decided to make the move to a fully cheapened crank in two stages - First stage, the same material as previously tried (Spec.2052) but hardened to only 241-269 Brinell. Second stage, produce the same crank, but from a material to spec.S.A.E.1045 (.4 Carbon). Note. The production cost of the Wraith Crank at the beginning of the war was £11. 16. 9. and the estimated saving on the new crank is at least £3. 15. 0. CRANKSHAFT DAMPER. Innumerable oscillation tests and diagrams have been taken in connection with this item, but the two major problems are: a) Can the customer tell the difference between the Humber Damper and the more usual R.R. Spring Drive and Damper. b)) Does the Humber Damper reduce the factor of reliability of the engine when correctly adapted to the engine, i.e. Correct inertia and Damping load, together with a camwheel that will take the shocks resulting from removal of the Spring Drive; and correctly balanced auxiliaries (Fan, pump, dynamo). Continued. | ||