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).
Failure of magnesium pedestal pistons after 1000 miles and the need for a design alteration.
| Identifier | ExFiles\Box 142\4\ scan0008 | |
| Date | 18th May 1927 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} DA.{Bernard Day - Chassis Design} X4112 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}4/LG18.5.27. PEDESTAL PISTONS - E.75540. X8040 We have recently been running a set of these pistons made of magnesium on a car. After about 1000 miles running five out of six of the gudgeon pins were loose in the pistons due to the bolt heads having pulled into the metal. It appears to us that whether aluminium or magnesium is used for these pistons it will be necessary to have some alteration in design so that the expansion of the piston head will not throw high stresses on the bearing surfaces under the bolt heads. Actually, we have had no pedestal pistons in alum: fail as yet. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||