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).
Piston clearance and flexibility to resolve rattling issues.
| Identifier | ExFiles\Box 48\1\ Scan166 | |
| Date | 6th October 1925 | |
| R.R. 493a (50 H) (D.D. 31, 12-6-25) J.H.L. EXPERIMENTAL REPORT. -3- Expl. No. REF.Hs{Lord Ernest Hives - Chair}/ACL/LG6.10.25. overcame the trouble. Even with this increased clearance .003 to .004", there was no evidence of piston slap when cold. We have also tried pistons with the clearance increased to .004 to .005" but with no better results. Another experiment we tried was to split the pistons on both the pressure and non-pressure sides in exactly the same way as the non-pressure side is at present split. The results were very satisfactory and no knock was evident either when starting from cold or when the engine was hot. These pistons however rattled at high speeds due to, no doubt, the increased f-lexibility causing the piston to 'spring' when subjected to greater side thrust. Our experiments seem to show that we want a more flexible skirt having a fairly good contact surface but not so flexible that we get rattle at the high speeds. The course we are now following is to increase the flexibility of the skirt. Hs{Lord Ernest Hives - Chair}/ACL. | ||