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).
Proposal to revert to an earlier gudgeon pin lock screw design due to post-war failures.
| Identifier | ExFiles\Box 81\2\ scan0077 | |
| Date | 1st November 1923 | |
| Oy4-E-11128 November 1st, 1923. Mr. Claude Johnson, Rolls-Royce, Ltd., London, England. (Copy for attention of Mr.Royce " " " " Mr.E.Platford " " " " Mr.E.Hives) Dear Sir: Ref: Proposal Sheet No.25 Thickening Gudgeon Pins We submit herewith proposal sheet No.25 proposing with the the re-version to the earlier type of gudgeon pin lock screw to increase the thickness of the gudgeon pin wall from .125 to .187. Our letter Oy1-W-78128 on this subject proposed increasing the size of the existing lock screw, but further experience of failure of the existing screws on service has forced us to the conclusion that the earlier post war screws were essentially better, because the taper formed a solid foundation for the screw in the pin in close proximity to the stem of the screw where it is hammered to and fro by the piston boss. As compared with this we think the screw thread on the screw at the lower side of the pin is not a secure foundation. We have had three cases on service where the threads on a number of screws have shaken loose and finally stripped in 5000 miles running. As far as we can find out the threads were a good fit at the start. We have examined pre-war cars with the 7/8" gudgeon pin and the older type of lock screw and find that after years of running these have given no trouble and the pin has not distorted out of round enough to do any harm either to the fit in the piston or in the little end bush. We are therefore proposing to revert to the earlier lock screw E-17768 | ||