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).
Technical report on the development and issues with self-adjusting tappets on the J.3 unit.
| Identifier | ExFiles\Box 106\5\ scan0067 | |
| Date | 12th September 1932 | |
| Y 5060 E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}3/MA.12.9.32. SELF ADJUSTING TAPPETS ON J.{Mr Johnson W.M.} 3. We have now had the self adjusting tappets running on J.3. unit and so far have only met with a moderate amount of success. Our first trouble was due to the Plunger valves not working and failing to allow oil to pass to the well below the Plunger, we have overcome this trouble for the time being by cutting down the length of the spring and so reducing the spring pressure for the initial opening of the valve, this of course is only a temporary measure as actually a much lower rating spring is required. After making this modification several of the plungers worked quite well but further trouble was experienced on some with the plungers gradually sinking in their casing and making the tappets very noisy. We have put down this trouble to the Bronze Bushes E.58571 which had only slight bearing surfaces for the eccentrics the greater part of the inner bearing surface being cut away to make an annular oil space, the Bushes were found to have "picked up" badly and it would have probably been only a question of time before the hole of the Bushes would have seized or picked up badly and causing the plungers to sink even against their return springs. Two new types of Bushes have now been fitted in order to overcome this trouble and are now being tried:- (a) Bushes in which the annular oil space has been completely removed and relying entirely on the eight .062 dia holes for lubrication. (b) Bushes in which the annular oil space has been removed but in which each pair of .062 dia holes has been connected by a groove .062 wide x .015 deep. So far the Bushes (b) appear to be the better since one or two of the plungers having the other bushes sink after a burst at high speed. The tappets are quiet at low speed but all the plungers are not perfectly steady and this can be put down to the following reasons :- | ||