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).
Fit of the gudgeon pin to address an 'elusive knock' in the piston.
| Identifier | ExFiles\Box 48\1\ Scan137 | |
| Date | 23th March 1921 | |
| R.R. 235. (500 H) (S.B. 80. 12-10-15) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1278 Hs.{Lord Ernest Hives - Chair} from BY.{R.W. Bailey - Chief Engineer} x 4190 RECEIVED Hs{Lord Ernest Hives - Chair} MAR 23 1921 BY4-P23.3.21. CHASSIS - PISTONS. RE ELUSIVE KNOCK. x4190. (1) EP.{G. Eric Platford - Chief Quality Engineer} is putting the fit of the Gudgeon Pin in the Piston to the Works in such a manner that it is almost impossible to produce Gudgeon Pins and positively to meet his requirements; the difference between a sliding fit and a push fit, providing both pin and hole are round, is in the neighborhood of .00015, and it must be conceded that to try and work within this limit is impossible. (2) The next point I wish to make clear is, that in order to obtain any benefit from a point of view of eliminating the elusive knock for any definite period, a tight fit in the region of .001 positively tight is required. This, however, would demand that we should fit Gudgeon Pins into hot pistons, which is more cumbersome although it could be adopted. (3) I am bringing forward the above facts in order to ascertain what are the probabilities of adopting the scheme you have worked out by the fitting of a special screw in place of the present one which prevents the pin rotating, as the adoption of this scheme would enable us to give reasonable limits on both the pin and the hole in the boss, so that the Gudgeon Pin would really become a production job. At the moment it certainly cannot be considered to be one in view of EP{G. Eric Platford - Chief Quality Engineer}'s requirements, which are logical, in view of the fact that unless he gets a tightish fit to start with that elusive knocks will develop almost before the car leaves the Works. BY.{R.W. Bailey - Chief Engineer} | ||