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).
Piston design experiments to address over-oiling and engine knocking.
| Identifier | ExFiles\Box 48\1\ Scan102 | |
| Date | 20th September 1919 | |
| Contd. -3-3 EHL/LG20.9.19. chassis' with the extra oil on the whole time but in some cases on those cars they have had definite over-oiling sufficient to oil up the plug. X.3651 We are running some pistons on the test engine which have a hole through the gudgeon pin to allow the oil to work through. There is an annular recess on the piston round the gudgeon pin to carry this oil round. We cannot say that so far we have found this has been any improvement as regards curing knocking pistons. X.3400 [struck through] 3663 LONGER PISTON - present design. We have machined and ground, ready to be fitted to an engine, some pistons of the present design which are 2.5.longer. We expect to be running some of these tomorrow. X.3651 PLUNGER WORKED BY OIL PRESSURE. We have also tried a plunger in the gudgeon pin worked by oil pressure so as to push the piston up against one wall of the cylinder. We find that this promises to be a help. The effectiveness of the plunger however, as regards over-coming knocks is influenced by how the piston beds against the cylinder wall, for instance, we found on one piston, that fitting the plunger so that it worked from the rear end of the gudgeon pin it made no difference but we worked it from the front end of the gudgeon pin, it cured the knock. We have some knocks which we cannot cure by this means. in connection with this plunger worked by oil pressure, we have had to turn an annular groove in the big end bearing. | ||