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).
Report page detailing piston manufacturing, testing, and laboratory equipment at Elektronmetall, and a brief note on a visit to Robert Bosch A.G.
| Identifier | ExFiles\Box 148\3\ scan0238 | |
| Date | 21th June 1937 | |
| -4- E/PSN.1/M.21.6.37. ELEKTRONMETALL, G.M.B.H. (Cont'd). (4) Tin plating of pistons (skirts only) is being practiced to minimize cold scuffing. A deposit .005 m.m. (.0002") thick is produced by immersing the piston for a few minutes in a solution of sodium stannate (Na{Mr Nadin}2SnO3. 3H2O). Dr. Mahle spoke very highly of the efficacy of this thin film, and exhibited plated and unplated pistons after a number of cold starts. The difference was remarkable. (5) We saw a number of pistons in the test dept. and museum which had failed by a fatigue crack across the crown at right angles to the gudgeon pin, and an aero engine piston of about 6 3/4" bore was seen in the shops with a pad on the underside of the crown centre, machined concentric with the gudgeon pin bore. We were not told the function of this, but assume that it was intended to limit deflection of the crown by bearing direct on the little end of the connecting rod. (6) The firm has a well equipped laboratory. Special equipment includes facilities for measuring fatigue strength at high temperatures, heat flow in pistons, etc. A spectograph is in use by means of which it is possible to determine the chemical composition of a sample in a few minutes. We were told that it was their practice to make static deflection tests on new piston designs. The load is distributed over the crown by a pad of rubber or water bag, and the distortion of the skirt, gudgeon pin bosses, ring grooves, etc., measured. ROBERT BOSCH, A.G. We were hurriedly conducted around a considerable portion of this large works, and were unable to form anything more than general impressions. We were told that our party was the first to be shown the production of fuel pumps. The green paste used for lapping the pump elements is a mixture of chromic oxide and oil. This is a useful material for polishing specimens for microscopic examination. (Cont'd). | ||