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).
Cracks in cylinder heads and proposing the addition of internal ribs as a solution.
| Identifier | ExFiles\Box 19\4\ Scan055 | |
| Date | 24th June 1930 | |
| X7772 To: Wor.{Arthur Wormald - General Works Manager} c.c. Sy From: Oy. c.c. Hs.{Lord Ernest Hives - Chair} Oy6/DM.{D. Munro}24.6.30. Cylinder Heads. Sec.5050. Btn. writes :- "We have recently had an appreciable number of cylinders heads which have developed cracks in service on the flat surface just above the horn bracket. Examination has been made of the material and this would indicate nothing to show why cracks should develop at this place. We are therefore, arranging for a number of small ribs to be put on the inside of this surface with a wide one just opposite the horn bracket facing so that an attempt will be made to get over this trouble on the next castings used. I enclose a copy of print A-12528 showing the general location of these cracks and the webs we are adding." It might be considered desirable to add such ribs, or at least a single one, opposite the horn bracket on any RR 50 P.I heads made for Springfield. I have written America about our experience on Brooklands, recommending in case of further trouble to get the horn back on the dash, as there can be little doubt that the crack is purely mechanical due to (a) Brittle metal. (b) Shimmy. (c) The overhung mass of the horn. Oy. | ||