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).
Piston seizures on Wraith & 25/30 models and recommended actions.
| Identifier | ExFiles\Box 148\3\ scan0374 | |
| Date | 19th August 1938 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} c. to Da.{Bernard Day - Chassis Design} c. to Da{Bernard Day - Chassis Design}/JNR.{Charles L. Jenner} 1256 RM{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}2/JH.19.8.38. WRAITH & 25/30 PISTONS. During your absence we have had Mr. Brookes of the Light Production Co. (Aerolite) to see us to discuss the several piston siezures that have recently occured on the 25/30. After an inspection of the pistons in question his opinion was that the trend of events to these siezures were started by sticking or gumming of the rings, then blow by and subsequent siezures. Pointing out that they had all occured following decarbonising without removing the carbon from around the top lands, he considers that they should always be decarbonised on the top lands when the engine generally is decarbonised. This in accordance with your memo. By.14/G.29.6.38. has been instructed to the depots to be carried out. The same memo. also calls for machining a .100 chamfer on the upper lands of the piston which Mr. Brookes does not recommend and quoted a manufacturer who had run into serious trouble through this operation. In view of this we consider therefore that the instruction to chamfer the pistons should be deleted, at least until we have more experience of this. The fact that the piston lands are to be decarbonised should be a big help on its own without any other modification in obviating piston siezures. Having the opinion that the siezures started by ring sticking he did not consider that any benefit would be derived by increasing the diameter of the top lands. However pistons are being produced for experimental trial in accordance with your memo. By.1/O.15.7.38. which even if clear of siezures etc. should, we consider be fitted in | ||