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).
Causes of Bentley piston seizures and comparing lubrication systems across various chassis.
| Identifier | ExFiles\Box 87\2\ scan0045 | |
| Date | 12th April 1935 | |
| x236 To Sg.{Arthur F. Sidgreaves - MD} and Her.from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Hd.{Mr Hayward/Mr Huddy} Mx.{John H Maddocks - Chief Proving Officer} [struck through] E/JMR. E/PGN. re Bentley Piston Seizures. With regard to the above, I attach herewith a memo E/McS.1/HP.11.4.35 reporting on the conditions under which these seizures have occurred. The marking of the seized pistons indicates that the trouble has started on the thrust side where the load is naturally heavier, and which is also the locality least lubricated by oil spray from the crank. The portion of the skirt which runs out of the cylinder barrel at the bottom of the stroke on the thrust side is in perfect condition. It appears to me that this trouble is the combined result of lack of oil, probably due to the oil being cold in the initial stages and excessively rich setting of the jet control. On the Bentley any excess fuel has to run into the engine owing to the semi downflow type of induction system employed. On the 20/25 chassis which is fitted with a similar carburetter control the major portion of the induction system is up-flow and this helps to keep the wet stuff out of the engine. On the Phantom 2 chassis we have a specially contrived control which turns on extra lubrication whenever the mixture is set to rich,or to the position bringing the starter carburetter into operation. This is a definite safeguard. On the SpectreCodename for Phantom III and Wraith there is no scheme of extra lubrication, but an oil temperature control unit is embodied in the system for the purpose of quickly warming up the oil. For effecting some permanent improvement the evidence certainly suggests - CONTINUED:- | ||