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).
Material suitability and design improvements for piston pins and articulated rod pins.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan337 | |
| Date | 11th August 1931 | |
| RG.{Mr Rowledge} ) FROM R.{Sir Henry Royce} HS.{Lord Ernest Hives - Chair} ) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} ORIGINAL R2/M11.8.31. ENGINE WORK GENERALLY. PISTON PINS AND ARTICULATED ROD PINS. 84486. X3859. It will be remembered that these were originally in C.H.N.S., and experience proved that this material was not suitable for the necessary bending stresses owing to the brittle shell first cracking, and naturally the core following. The WW. suggestion was that these should be altered to a steel especially suitablefor hardening and tempering like the road spring silico manganese, and that the pins were to be as tough and hard as possible, but the exact temper to be found by experimental fatigue test such as the Arnold test. After the failure of the C.H.N.S. we noticed you used silchrome manganese which we assumed was hardened and tempered as suggested for the piston pins, but in this case either the lubrication or the material proved too soft and you are now using the air hardening gear steel. We assume that this is carburised when nearly finished to size and given a hard skin, but has a tougher and stronger core than C.H.N.S. We may take this as proved from the experience with the back axle gear teeth on the 20HP. One would like a fatigue test made of this compared with the present piston pin material because it would seem that the piston pins should be made of the same material if it will bear the bending stress, and would improve the wearing qualities of the little end. We are very pleased to hear that you are trying the oiling holes in a diagonal position because it is as well to have the holes away from the stress and away from the maximum load, provided that we can replenish the oil film satisfactorily, so we would like this idea to be carried out also. If it were equally successful with the holes on the centre it should be used in preference, but naturally it may be sometimes difficult to tell which is the better. R.{Sir Henry Royce} | ||