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).
Technical memorandum discussing the performance, faults, and potential improvements of split type pistons.
| Identifier | ExFiles\Box 35\2\ scan 170 | |
| Date | 12th December 1919 | |
| x2748 To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair}. c. to CJ. c. to BN.{W.O. Bentley / Mr Barrington} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Wor.{Arthur Wormald - General Works Manager} c. to EP.{G. Eric Platford - Chief Quality Engineer} ----------- Hs{Lord Ernest Hives - Chair}3/LG12.12.19. ----------- X.3732. RE PISTONS. X.2748. ----------- X.3754. ----- Split type Pistons. We have now had a fair experience with these pistons and are in a better position to judge their faults and merits. The fault we have found with these pistons is that in some cases the clearances increase with running. On one particular car we had under observation, the fitting portion of the piston increased from .0045" to .0065" at the top and from .002" to .0035" at the bottom. This occurred in 2,000 miles running. With these clearances there were piston knocks when the engine was started up cold; they went off when the water got hot, but it means, of course, that when the pistons get into this condition they do not fulfil the Sales Depts' demand of no piston knocks under any condition. The split pistons at their worst are still a very distinct improvement over the split trunk piston. The present split piston has never been designed for a split pistons. Wr feel certain that very considerable improvement could be made in the split pistons, if the design was gone over andthe metal better distributed on the split piston. We have tested a present type split piston and find that the deflection all takes place in the root of the tongue left by the splitting. Mr. Day is at present looking over the design with a view to effecting an improvement. As the split piston is still the Contd. | ||