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).
From Wilcox-Rich Corporation comparing Rich Type, Cylindrical, and Hydraulic engine tappets.
| Identifier | ExFiles\Box 17\6\ Scan270 | |
| Date | 25th June 1934 | |
| WILCOX-RICH CORPORATION Rolls-Royce, Ltd. Page Two June 25, 1934 RICH TYPE TAPPETS Designed primarily for rugged heavy duty engines of all types where mushroom lifters are used, the Rich Type tappet is practically the unanimous choice of the heavy duty engine-builders in this country. It is of mono-piece construction, consisting of a steel forging conformed to size, assuring ample strength throughout the high stress areas; namely, the neck and platform sections. To the platform itself, which is slightly cupped during the forging operation, is welded by an electrical arc process a new highly alloyed iron possessing in its final analysis almost the identical characteristics of the present Wilcox Tappet iron. The resulting structure insures the ideal combination of strength and unexcelled facial wearing qualities - of absolute necessity in heavy duty work. CYLINDRICAL TAPPETS Of new and prime importance is the development surrounding the so-called cylindrical type lifter. This has been brought about very recently in order to lower engine costs. The advantage of being able to bore the tappet guide in the block without having removeable tappet brackets is of course a tremendous economy. The cylindrical lifter in this case is likely to replace the mushroom type inasmuch as the mushroom type cannot be removed from the engine without removing the camshaft. This, as you appreciate, is a very costly service operation. The change from a mushroom type lifter to a cylindrical lifter however calls for reduced base circle cams and, in many cases, revision in engine block design to permit tappet removal, without interference from the valve guide. The cylindrical type tappet, either with or without adjustment, has reached an advanced stage of design, to the point where it is possible to duplicate the light weight features of the mushroom lifter and at the same time provide ample strength and excellent wearing qualities both on the body and the face. Under certain conditions where it is not advisable to reduce the base circle of the cam, we can develop a special face radius to permit the substitution of a smaller diameter lifter. As an example, in one engine which we are now working on, the conventional mushroom type lifter has a head diameter of 1-3/8" and our proposed substitute is a cylindrical type lifter having an outside diameter of 1". The lift curves in both cases remain practically identical. HYDRAULIC LIFTERS The automatic self-adjusting hydraulic lifter has been developed to a production status within the past three years. It is now used as standard equipment on Pierce-Arrow engines and quite a number of heavy duty engines such as the Doman & Marks air-cooled jobs which at the present time are being supplied for military work both in the United States and some European countries. In making engine layouts for the adoption of hydraulic lifters, it must be considered that each engine has individual characteristics; therefore we shall not attempt to discuss the final workings of the hydraulic lifter itself but would suggest if this is of | ||