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).
Letter from designer Frank B. Halford discussing proposed modifications to the hydraulic valve gear for the 3 1/2 litre Bentley.
| Identifier | ExFiles\Box 88\4\ scan0110 | |
| Date | 6th September 1934 | |
| FRANK B. HALFORD, F.R.Ae.S. DESIGNER OF AERO AND AUTOMOBILE ENGINES. Telephone Nos.: Gerrard 1217. Gerrard 1218. My Ref. ESM/MFS. Your Ref. HS{Lord Ernest Hives - Chair}/Smth.24/KW. 8 & 9 GOLDEN SQUARE, LONDON, W.1. 6th September, 1934. Rolls-Royce Ltd., Derby. Dear Sirs, Hydraulic Valve Gear. I enclose herewith prints of drawing nos. Sk.4476, 4477, showing further suggested modifications to the hydraulic rocker for the 3½ litre Bentley valve gear. My aim has been to decrease the equivalent reciprocating weight of the rocker, and to improve its general shape whilst retaining a section of ample strength and rigidity. The attached schedule sets out the comparison and shows that the proposed rocker Sk.4477 should have a rotational moment of inertia only 52% of the value calculated for the original experimental rocker. At the same time, the proposed H-Section is more economical in material and gives a reduction in maximum stress by about 41%. You will note that I have raised the fulcrum centre slightly to minimise the amount of "crank" in the rocker, and made several minor changes in the hydraulic unit to decrease its height. A slight saving has been effected by reducing the lengths of the fulcrum-spindle bearings without introducing what I consider to be excessive loads for fully lubricated bushes. | ||