The investigation and attempted improvements for noisy silent tappets.
| Identifier | ExFiles\Box 11\5\ 05-page039 | |
| Date | 14th April 1934 | |
| To Hs. {Lord Ernest Hives - Chair} From G.W.H. Hotel de France, Chateauroux(French test region), FRANCE. 14.4.34. 28-EX. RE. SILENT TAPPETS. We have made an improvement to the silent tappets, No's 11 & 12 we have definitely cured of losing the oil and being noisy. No.1 & 6 we have made to become quiet in a few minutes, but after standing for some time the oil is lost out of the barrel. This also occurs when the oil is hot, i.e. 80°C whilst going slow through a village, at the end of the village they have become noisy. We can get them to work with a less oil pressure than what is now being used. The chief trouble we have found is lack of maintaining the oil supply. We measured the plungers on the diameter and found most of them .005" larger on the dia. at the top than at the bottom. This we found was sufficient to keep the oil supply on the low side. We therefore polished the plungers at the top portion for approx. .250" down, making the dia. .005" less. This has increased the supply of oil sufficiently to keep the plunger steady. We have previously made sure of the ball valve seating. No.1 & 6, the plungers are on the small side and the oil leaks past the plunger. The clearances of the eccentrics are too large, oil runs out at either side. This is what is causing us trouble with the breather and oil consumption. The top of the cylinder head is full of oil. The tappets are not satisfactory even with the 'R' valve springs fitted. At 68 M.P.H. one starts to hear them clatter, and they remain generally noisy (i.e. one has to listen for it) up to maximum speeds. We found two push rods bent, No's 11 & 12, when we dismantled the engine. These were replaced. Our oil guard is not yet 100%. It is too small to cope with the quantity of oil in the rocker cover. | ||
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).