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).
Fit and condition of a production air valve for chassis 58-AL.
| Identifier | ExFiles\Box 47\2\ Scan088 | |
| Date | 15th October 1928 | |
| X4117 To Hm.{Capt. W. Hallam - Head Repairs} from Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} c. to BY.{R.W. Bailey - Chief Engineer} Sft.{Mr Swift} c. to Cr.{Mr Cra???ster / Mr Chichester} EWT. Hs{Lord Ernest Hives - Chair}/GWH{George W. Hancock - Head Chateauroux}/LG15.10.28. RE. MAJOR HOUSTOUN. Chassis 58-AL. X4117 X8040 With reference to Hm{Capt. W. Hallam - Head Repairs}/NRC{N. R. Chandler}17/MW11.10.28. We have taken a standard production air valve from the Test Dept. and had it carefully checked for size. The suction chamber in the large bore was .0002" on the small side; this is an allowance of + .00025" on the drawing. The small bore was to size. The suction piston large dia. was to size - .00025" allowed. The small dia. was to size .00025" allowed. Therefore this particular air valve is as good a fit as is allowed. They can be an easier fit. It was heated up to 85°C / 90°C and remained perfectly free. We have had similar experiences as quoted, but in all instances it has been due to foreign matter entering the air valve, and slightly scoring the bore and piston. We are of the opinion that after an air intake has been in use for some time, their working surfaces become skin-hard due to polishing etc. which prevents the dust penetrating and no further trouble occurs. Hs{Lord Ernest Hives - Chair}/G.W.Hancock. | ||