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).
Bulk production of pistons, material constraints, and a re-designed split piston.
| Identifier | ExFiles\Box 77\3\ scan0090 | |
| Date | 21th January 1920 | |
| R.R. 235 A (100 T) (S.F. 246. 6-8-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2460. X 3451 2 To [s]H.{Arthur M. Hanbury - Head Complaints}[/s] from Bm. (Handwritten 'Mr.' above 'H.{Arthur M. Hanbury - Head Complaints}') Copy to CG. Copy to [s]Wdr.[/s] Copy to Bm. Copy to GT. Copy to Ck.{Mr Clark} Hn{F. C. Honeyman - Retail orders}14/W21.1.20. [s]X 3432[/s] X. 3451 Re Bulk Production of Pistons. It is thought by Mr. Wormald that there is a fair chance of the Moulders returning to work quite shortly, say next week. Directly the Moulders return it will be necessary for Mr. Wormald to have practically carte blanche as regards the number of pistons he is allowed to make, and we must therefore make up our minds now which type he is to make. It is unfortunate that we cannot experiment usefully with cast iron pistons until the Moulders come back, owing to the impossibility of obtaining material with which to experiment other than existing castings and we cannot recommend proceeding with either the old type cast iron piston or this piston made from the same casting and split. We have not had enough castings to pursue our experiments with the letter box type of split in cast iron. In short, we feel that cast iron pistons are ruled out as regards immediate bulk production. We have re-designed Mr. Hives' Split Piston, and this is shown on drawing H.2820 forwarded to you today; you will see that no serious change has been made, but the piston is now designed so that the spring leaves are more efficient as cantilever springs and this should improve the surface bedding. We have also widened the circumferential slot in accordance with your recent suggestion. These pistons have been fitted to the 10,000 miles car, and also to the Drivers' Demonstration Car and on these two cars have run a total of 2,000 miles. These pistons have also been run for 10 hrs. on the bench. They appear to be very good indeed. We believe that this altered design will overcome the fault of the original split piston as regards the tendency of the leaves to take a permanent set. It must be remembered that the original split piston was never designed as a split piston and its good performance was in spite of this serious handicap. We think we should instruct Mr. Wormald that he can go ahead, aiming at 30 or 40 sets a week of this piston (to H2820). On the return of the Moulders we can get ahead with our cast iron experiments but I have hope that we shall ultimately be completely satisfied with some type of aluminium piston. Bm. | ||