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).
Description of various engine lubrication systems, comparing automobile and aircraft designs.
| Identifier | ExFiles\Box 141\2\ scan0148 | |
| Date | 31th May 1936 guessed | |
| 4. object lesson of this fault. The maintenance of moderate temperatures in the main body of the oil is accomplished in a variety of ways. Aircraft engines generally employ the dry sump system with a storage tank independent of the engine crankcase. An oil cooler, providing a controlled oil inlet supply temperature is invariably employed with the larger engines. Automobile engines employ the floor of the oil pan in the air wash of the moving vehicle to maintain the main body of the oil at a reasonable temperature. Unless the area of surface exposed to the air is calculated for the most severe conditions, temperatures may get unreasonably high with continuous high speed driving. Figure 4 illustrates one form of the pump and splash system. Reservoirs constantly replenished by a dual pump supply oil through large ducts to the main bearings. The rods are provided with dippers which scoop oil from individual troughs. A labyrinthine passage (Figure 5) must be followed by the oil in its return to the pump suction line, a winding series of baffles requiring it to flow in intimate contact with the floor and sides of the oil pan. Figure 6 shows a combined low pressure and splash system. At low engine RPM's ample oil is provided to the connecting rods by dippers picking it up from the troughs. At high RPM's, the supply tubes for the troughs discharge oil under pressure directly into the path of the connecting rod dipper. (Figure 7) The main bearings receive oil from a passage drilled through the cylinder block fore and aft and supplied by pump pressure. Figure 8 illustrates a full force feed system as used in another automobile engine. Oil pumped through a large gallery running lengthwise of the crankcase flows through horizontal passages to each main bearing and from each main journal to two connecting rod crankpins, except for the end main bearings which each supply one only, the flow being carried by drilled openings in the crankshaft. Camshafts are supplied under pressure from the gallery. The supply tube to the connecting rod bearing through the pin, registers once each revolution with a hole drilled through the bearing and through the connecting rod to the piston pin. Figure 9 illustrates the system used in an inverted air-cooled six cylinder aircraft engine. This engine is of the valve in head type with valves actuated by an overhead camshaft. The oil supply for the main and connecting rod bearings is introduced through the accessory drive shaft, with passages through the crankcheek of each main shaft journal leading to the adjacent connecting rod crankpin. With an oil lead to each mainshaft journal and a continuous flow through the drilled crankshaft, there is little opportunity for failure of the oil supply to any bearing due to stoppage of any one oil lead. It will also be noted that plugs are used in the journals and crankpins, taking oil for the bearing near the center of the hollow pin and permitting any foreign matter to be centrifuged out. Pressure lubrication reaches the camshaft bearings through the hollow shaft which acts as a header. The valve mechanism receives oil through small holes drilled in the shaft between the inlet and exhaust cam. It may be of in- | ||