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).
Proposed modification to the valve rocker mechanism to reduce noise and wear.
| Identifier | ExFiles\Box 106\5\ scan0007 | |
| Date | 22th April 1927 | |
| X.5060 R.{Sir Henry Royce} c.Hs.{Lord Ernest Hives - Chair} c.F. (Strikethrough) c.R. (Strikethrough) C.Hox. (Strikethrough) BY10/H.{Arthur M. Hanbury - Head Complaints} 22.4.27. ------------------ VALVE ROCKER MECHANISM. ----------------------- Referring to R4/M.16.4.27. I made the suggestion for the proposed modification in the first place as the result of a carefully reasoned train of ideas. When tried in practice, Mx.{John H Maddocks - Chief Proving Officer} confirmed that it had obviated his trouble, and further, that he could run with as much as .008 clearance between the tappets on the engines so treated, whereas previously he had clicking of the valves on their seats with a clearance not exceeding .002 The object of the modification is to bring the forces controlling the opening and closing of the valve absolutely axial at the moment when the valve is at the end of its travel, i.e. seated or about to open or close. At the moment of opening it is obvious that the forces on the exhaust valve are maximum, as opposing the force on the lever there are the following forces:- a/- gas pressure. b/- Inertia of the valve. c/- spring pressure. In the case of the inlet there is no gas pressure. If the rocker is travelling across the end of the tappet at this moment, it means that the maximum amount of scrub and therefore thrust, on the guide, takes place, the valve is displaced, the guide is worn, and the general truth of the mechanism is definitely affected. [Stamp: COVENTRY] [Stamp: DESCRIPTION] [Stamp: CONTINUED] I held this opinion for some time, and when Mx.{John H Maddocks - Chief Proving Officer} [Stamp: per] referred his trouble to me I suggested this modification as the right way out. Incidentally, I found afterwards that [Stamp: M's p/a] Mr.Hancock had, by a process using packings, arrived at the [Stamp: to] same conclusion by actual trial, both the 20 HP. and Phantom showing very improved quietness characteristics on the tappet operation with this modification. [Stamp: backed pa{Mr Paterson}] BY.{R.W. Bailey - Chief Engineer} [Signature: By] [Stamp: DERBY] [Stamp: ROLLS-ROYCE LIMITED] [Stamp: ENG. DEPT.] [Handwritten: V 2790] [Stamp: HH. DEB. (DDM. YEAR) OR 45W-52-1-50) WH. 306-19] | ||