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).
Proposed suggestions to cure over-oiling with the silent ram piston on the 40/50 HP chassis.
| Identifier | ExFiles\Box 77\3\ scan0071 | |
| Date | 24th November 1919 | |
| X 3439 To EH. from E.{Mr Elliott - Chief Engineer} Copy to CJ. " " BN.{W.O. Bentley / Mr Barrington} " " DA.{Bernard Day - Chassis Design} " " EFC. RE SILENT RAM PISTON. X.3715. The following suggestions are proposed to cure over-oiling with the silent ram piston on the 40/50 H.P. chassis (1) Intermittent feed. With the original ram piston Lec. 1152 the oilway was supposed to be open all the time. Mr. Royce proposes to cut down the oil feed so that there is only a supply during the power stroke and the induction stroke. He points out that this may be of assistance in two ways - Firstly, there will be less oil leak due to the oil being fed for a shorter period, and secondly, it may permit the use of a smaller active plunger owing to definite Hydraulic confinement of the oil. This can be applied to the present rampiston unaltered. (2) Ram with annular oil collecting chamber. Mr. Royce proposes to make the ram as in diagrams "A" or "B" in which an annular chamber collects the pressure oil leak from the ram and delivers it to the inside of the piston. The piston ring can be fitted either to the active or the non-active plunger. This modification can be applied to the present ram piston with small pattern alteration. The press of the small ram fig (a) can be supplemented by spring pressure as shewn. (3) Lower scraper ring - Mr. Royce suggests that it may be necessary to fit a lower scraper RING to keep down the oil which escapes from the ram and is bounced back by the crank and connecting rod big end. To get in such a ring it is necessary to use three piston rings only at the top and reduce the outer diameter of the ram to 1.900", the ram then occupying a position .500" above the centre of the piston pin. Furthermore, it is not possible to have an oil collecting ring underneath the scraper without this feature running out of the cylinder end and causing a tap. To overcome this trouble Mr. Royce proposes to drill holes in the bottom of the ring groove, as in diagram. Contd. | ||