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).
Letter from a piston specialist regarding 4.5L Bentley pistons, specifically discussing side clearance on scraper rings to improve oil consumption.
| Identifier | ExFiles\Box 148\3\ scan0149 | |
| Date | 24th August 1936 | |
| SERVICE DEPOTS LONDON 89 BLACKFRIARS RD S.E.1 TELEPHONE: WATERLOO 5762-3 BIRMINGHAM 143 SUFFOLK STREET TELEPHONE: MIDLAND 0638 MANCHESTER 232 DEANSGATE TELEPHONE: BLACKFRIARS 5914 NEWCASTLE MILLICAN'S BUILDINGS, MARKET ST TELEPHONE 23874 ON ADMIRALTY, WAR OFFICE AIR MINISTRY, INDIA OFFICE LISTS WELLWORTHY PISTON RINGS LIMITED PISTON & PISTON RING SPECIALISTS LYMINGTON HANTS WORKS & HEAD OFFICE: STANFORD RD DIRECTORS: G.{Mr Griffiths - Chief Accountant / Mr Gnapp} H.{Arthur M. Hanbury - Head Complaints} ALEXANDER J.{Mr Johnson W.M.} W. HOWLETT C. B. KAY P. WALDEN OUR REF JH/BH SERVICE DEPOTS LEEDS 82 WOODHOUSE LANE TELEPHONE 25774 CROYDON 246 HIGH STREET TELEPHONE 0234 SOUTHAMPTON 17 PORTSWOOD ROAD TELEPHONE: 74778 HULL 285 ANLABY ROAD TELEPHONE: 15312 TELEPHONE: LYMINGTON 520 (4 LINES) TELEGRAMS: WELLWORTHY CODE: MARCONI YOUR REF 24th August.1936 W.A.Robotham. Esq. Messrs. Rolls Royce Ltd., DERBY. Dear Mr. Robotham: There are two things I wanted to write you about. The first is, as probably you are aware from Mr. Lappin, I went up to see him at your London Depot and placed an order for a 4½-Bentley and I was wondering if we did produce any pistons for your 4½ Bentley whether you would care to put them in that engine, or when my engine is likely to be ready. On this point, however, I should if you feel it is possible like to have a chat. The other point is, I have been looking through Mr. Blackith's cards and records, copies of which you have got, and I do want to emphasise the question of side clearance on your scraper ring. On the Bentley job with the Aerolite piston you have only got a clearance for the scraper ring vertically of 1 thou. Now this is very definitely wrong. It should be minimum 3 and maximum 4. If you get more than 4 you over do it and defeat your object, but if you work to the limit I have suggested the ring will collect oil in the ring groove and the pressure of the ring when moving up and down will force the oil out of the groove in the form of a pump and providing you have got holes enough at the back, as you have, this will undoubtedly do a great deal towards improving oil consumption. With regard to the two sets of pistons which you sent us along we checked these over for the points such as concentricity of grooves and so on, and am pleased to say these are quite good jobs, no complaints can be made on this, with the exception that the depth of groove was insufficient on [Handwritten text] [Top right corner] X1256 [Above recipient address] Matthews / Sewell. / Please return after - / perusal [Left margin] Mths{Reg Matthews} / Sewell / We ought to confirm this statement or otherwise / Rm{William Robotham - Chief Engineer} | ||