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).
Design of Bentley valves to prevent them from dropping into the engine cylinder.
| Identifier | ExFiles\Box 88\4\ scan0047 | |
| Date | 14th March 1934 | |
| x254 To Sg.{Arthur F. Sidgreaves - MD} from E.{Mr Elliott - Chief Engineer} c. Wcr. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} E.1/HP.14.3.34. re Bentley Valves. Replying to Sg.{Arthur F. Sidgreaves - MD}10/E.12.3.34, there is no doubt that provision would have been made on all designs of overhead valve engines to prevent the valve dropping into the cylinder if it were an easy and convenient matter. The standard practice is to take the risk, in this respect, except that in some cases the valves are sufficiently large to overlap the cylinder bore on some detachable head designs and ledge on the edge of the cylinder casting in the event of complete valve spring failure and washer assembly coming adrift. We have considered before in the case of the Bentley turning a groove in the valve stem and fitting a spring ring. The objections to this are the local weakening of the valve stem and the difficulty of keeping the spring ring in position under the acceleration effects which represent several hundred times gravity. Since receiving your note however we have looked up this matter again and it has occurred to me that we could extend the valve spring washer downwards over the top of the spring ring so that the ring would be definitely imprisoned, and the fidgeting might not prove sufficient to wear the parts seriously during the normal life of the valve. We are persevering with this scheme with a view to trying it out on an engine. E.{Mr Elliott - Chief Engineer} | ||