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).
Design, testing, and grinding instructions for a Pedestal Piston for India 3.
| Identifier | WestWitteringFiles\T\2July1928-December1928\ Scan043 | |
| Date | 24th July 1928 | |
| ORIGINAL FROM E.{Mr Elliott - Chief Engineer} C. to HS.{Lord Ernest Hives - Chair} PEDESTAL PISTON - INDIA 3. E3/M24.7.28. X5040 Y741 We send herewith LeC.2578. shewing the above. This piston should be tested with the scraper ring at the bottom, and also in an alternative form, where the dia. at the bottom of the skirt is controlled by a ring of Invara steel, or other steel found suitable. The idea is that the aluminium skirt tends to contract on to the steel ring as the piston cools, and is thereby prevented from following its own laws of contraction, thus avoiding piston slap cold. The upper part is admittedly left flexible, and operates in the same way as the present piston. The Invara ring should therefore be put in with sufficient tightness, and the piston ground after assembly. The aluminium ring riveted to the bottom of the skirt is split so as to become part of the piston, and the rivets securing it have tapered stems in reamed holes. These rivets should be put in with a certain amount of draw so as to be set up against the inertia load, which we estimate amounts to about 30 lbs at 3000 RPM. The riveting operation will make the rivets a tight fit in the skirt of the piston itself. Would you kindly issue the necessary instructions for testing on India 3. When grinding the piston the lands between the rings and the edge of the crown should be ground eccentric with the skirt the requisite distance for providing concentricity when the piston is hot. The sides of the upper portion of the skirt should be ground away eccentrically tapering away to nothing at the bottom. We realise that the final effect at working temperature will be to throw the skirt slightly out of line axially with the head, but we think this is the best practical compromise that can be made to avoid introducing further complicated grinding. E.{Mr Elliott - Chief Engineer} | ||