oil separator. A device used to remove oil from the air discharged from an oil-lubricated air pump. A wet, vane-type air pump is lubricated and sealed by a small amount of engine oil flowing through the pump. This oil must be removed before the air can be used.
An oil separator contains a series of baffles over which the pump-discharge air must pass. Any oil in the air sticks to the baffles and drains to the bottom of the separator housing, and from here it is returned to the engine crankcase. Air from which the oil has been removed leaves the separator from a connection above and beyond the baffles.
oil slinger. A ridge around a rotating shaft on the engine side of an oil seal.
The slinger throws much of the oil away from the shaft, back into the engine crankcase, before it reaches the oil seal.
oil sump (engine lubricating system component). An engine component designed to hold the lubricating oil. In a wet-sump engine, the entire supply of oil is held in the sump. In a dry-sump engine, the sump is small and holds the oil only until the scavenger pump can move it into an external oil tank.
oil tank pressurizing valve (turbine lubricating system component). A check valve in the oil tank vent system that maintains an air pressure of between 3 and 6 psi on the oil. This pressure assures a positive flow of oil to the engine-driven oil pump at all altitudes.
oil temperature indicator (aircraft engine instrument). An engine instrument that shows the pilot or flight engineer the temperature of the oil as it enters the engine.
oil temperature regulator (reciprocating engine component). The device used to keep the temperature of the oil entering the engine within allowable limits. This type of regulator controls the temperature by directing hot oil through the core of the oil cooler and cold oil around the cooler or between the core and the shell.
oil wiper ring (reciprocating engine component). One of the cast-iron rings installed in the grooves around a piston. The oil wiper ring is the bottom ring on a piston, and its purpose is to direct oil up between the piston and the cylinder wall for lubrication and sealing. The amount of oil allowed to remain between the piston and the cylinder wall is determined by the oil control ring. See oil control ring.
oleo strut (aircraft shock absorber). A type of hydropneumatic (oil-air) shock absorber used on aircraft landing gear. The shock of the landing impact is absorbed by oil flowing through a metering orifice (restricting hole). The smaller shocks from taxiing are taken up by a cushion of compressed air.
Omega navigation system. A worldwide, electronic, hyperbolic navigation system. A master and one or more slave stations transmit a CW (continuous wave) signal simultaneously on the same VLF (very-low-frequency) carrier. The receiving aircraft measures the phase difference between these signals as they are received, and plots, on a hyperbolic chart, the line of position on which this phase difference can occur. The lines of position from two Omega stations cross at the location of the aircraft.