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).
Lubrication issues with the valve tappet and rocker shaft on the 20 HP engine, particularly during cold starts.
| Identifier | ExFiles\Box 106\5\ scan0023 | |
| Date | 18th April 1928 | |
| To E.{Mr Elliott - Chief Engineer} from Hs.{Lord Ernest Hives - Chair} Hs{Lord Ernest Hives - Chair}5/LG18.4.28. 20 HP. RR. VALVE TAPPET AND ROCKER SHAFT LUBRICATION. We are frequently receiving evidence to shew the need of a more copious oil supply to the tappets, rockers and valve ends on our standard production 20 HP. This need is most evident when starting an engine from cold during about the first 20 mins. 'warming up' and becomes manifest by tappet knocks and wear on the valve ends and tappet pins. When an engine is stopped after an average run the oil drains away from the hot parts leaving these in a more or less dry state and when starting up again from cold a considerable period elapses before such parts as the tappets rockers and valve ends receive any appreciable degree of lubrication. In an attempt to overcome this defect the Expl: and Test Depts. have tested arrangements of the rocker shaft whereby a more plentiful supply of oil was allowed down the push rods by holes drilled in the tubular rocker shaft which came in line with the holes in the rockers on the push rod side and also by holes on the valve side but which, in the latter case, only registered with the passage in the rocker when the valve was open. This arrangement certainly amounted to a more liberal supply of oil to these parts during the time of normal running i.e., when the engine was warm - but failed with regard to getting the oil quickly to the required parts when starting from cold which was the condition desired. A further disadvantage with this scheme contd:- | ||