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).
The testing of magnesium pistons, detailing weight savings and cracking issues.
| Identifier | ExFiles\Box 142\4\ scan0002 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}9/LG23. 7. 25. To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} HY.{Tom Haldenby - Plant Engineer} c. to Wor.{Arthur Wormald - General Works Manager} MAGNESIUM PISTONS. Magnesium pistons - made according to the standard design - have been tested on an EAC. test bench engine and have run for a total of 22 1/4 hrs. in connection with other tests. The weight of a magnesium piston is 21.25 ozs. without rings and gudgeon pin, and the std. aluminium piston, of the same compression ratio weighs 28 ozs. The magnesium piston therefore shows a saving of 6.25 ozs. The pistons were examined after the run and three were found to be cracked - the crack starting opposite the saw car in the skirt on the non-pressure side and running through the ring stop hole as shown in the sketch. Apart from this the condition of the pistons seemed similar to the standard aluminium pistons. CRACK The magnesium alloy used was :- 87% magnesium. 13% copper! Hs.{Lord Ernest Hives - Chair} | ||