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).
Investigation into oil leaks related to a felt packing seal and crankcase pressure.
Identifier | ExFiles\Box 115\3\ scan0058 | |
Date | 6th October 1937 | |
-2- RM{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}4/MR.6.10.37. (1) Considering the felt packing itself, which in theory should constitute the actual oil seal. We have tried four different ways of fitting the felt. We have tried increasing the pressure of the felt on the crank, and this makes the felt "wave" or "buckle", thus causing uneven pressure on the crank, and not preventing the leak. Alteration to the end cover (which carries the felt) shown on Rm.{William Robotham - Chief Engineer}455 has been tried. The feature of this modification was an attempt to release the pressure of oil working on the felt, and also to drain off some of the oil soaked up by the felt, as it absorbs oil like a sponge. This experiment did not reduce the leak. An investigation of the pressures acting on both sides of the felt:- (a) Crankcase pressure from piston "blow-by". (b) Pressure in clutch pit created by "fan", characteristic of flywheel. These two pressures were measured at points adjacent to the felt itself, as well as the general pressure in the crankcase. The Wraith engine like production 25/30 and Bentley, has a crankcase breather, which is part of the oil filler and is open to the atmosphere. Prior to this design, it was our practice to utilise the air intake depression for extraction of crankcase fumes. The two different conditions of crankcase pressure as affected by fume extraction, was therefore borne in mind at this stage. Built to specification, the "general" crankcase pressure was found to be atmospheric. Also, measured against the felt the pressure was found to be the same. At the corresponding position near the felt, the clutch pit pressure was found to be .100" H20. All this meant, therefore, that as far as pressures were concerned, assistance towards prevention of a leak would result. | ||