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).
Recommendations for the standard practice of fitting aluminium pistons.
| Identifier | ExFiles\Box 35\2\ scan 144 | |
| Date | 8th October 1919 | |
| X2748 PY. from EP.{G. Eric Platford - Chief Quality Engineer} c. to EM. c. to EH. c. to Wor.{Arthur Wormald - General Works Manager} EP{G. Eric Platford - Chief Quality Engineer}8/PS.10.19. 8th. October, 1919. RE. FITTING OF ALUMINIUM PISTONS. In view of the experience we have now had with the latest type clearance aluminium pistons, and the trouble we are having on test, we recommend that the following points should be adopted as standard practice in supplying and fitting pistons for any existing engines, or engines coming on test. This we have found is necessary in order to produce cars which can be despatched as satisfactory :- 1. One of the holes in the gudgeon pin boss into which the locking pin fits, should be made clear by at least .015". We have found that the fixing of the two locking pins causes considerable distortion of the piston. This has been demonstrated to EH, who has promised to [inserted: recommend] [scratched out: instruct] accordingly. 2. Before fixing pistons, they should be tried in their respective cylinder bore, and should be worked up and down in the cylinder bore, pressure being exerted on all sides of the piston, so as to obtain conception of the condition of bedding. It is essential that [inserted: a good] surface bedding should be obtained. It has been found that the grinding on some of the pistons is very "wavy", and causes line contacts, which are bad for piston knocks and seizing, and such pistons should not be used. This action will also show any irregularities or hard spots there may be on the piston, which should be eased down so as to obtain surface bedding. We also find that the clearance of the piston at the end of the gudgeon pin should be extended. The portion of the piston under the bottom ring at this place should be eased, and the clearance extended around the piston Contd. | ||