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 66\1\ scan0061 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. +8040 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} BY.{R.W. Bailey - Chief 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. [SKETCH OF A PISTON WITH AN ARROW POINTING TO A FRACTURE LABELLED 'CRACK'] The magnesium alloy used was :- 87% magnesium. 13% copper 1/2 Hs.{Lord Ernest Hives - Chair} | ||