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).
Experiments to reduce piston knock using an oil-fed cylinder, as suggested by Mr. Royce.
| Identifier | WestWitteringFiles\D\October1919\ Scan6 | |
| Date | 9th October 1919 | |
| To R.{Sir Henry Royce} from KH. c. to CG. c. to DN. c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to BY.{R.W. Bailey - Chief Engineer} ORIGINAL. EH2/LG9.10.19. 9th. Oct. 1919. x.2448 x.3651 RE PISTON KNOCKS. We have been experimenting with some standard pistons into which, on the non-pressure side, we have screwed a small cylinder. Into this cylinder we have fitted a piston which is 1.0" diameter. We have arranged an oil feed from the gudgeon pin to feed oil to the back of the piston. There is an annulus in the big end bearing so that we get the main oil pressure at this point. This is the scheme suggested by Mr. Royce; it promised to be good. We find that the success of this scheme is not so much due to the pressure of the oil keeping the piston against the side of the cylinder but to the fact that when this small cylinder is completely full of oil it is very difficult for the piston to cross over quickly enough to cause a knock because there is nowhere for the oil to leak out quickly enough for this to happen. The oil feed has simply got to be sufficient to replace any of the oil which is squeezed or leaks out. We find that if we use a spring instead of oil pressure we do not get as good results. With the spring fitted, it slightly reduces the knock at very small throttle openings but if we increase the load and open the throttle a little more, the knocks are still bad. We have tried with various springs up to 30 lbs. pressure. Contd. | ||