Jet Propulsion

Oil

Turbine engine lubrication systems are logically divided into three basic sub-systems. These are:

• Pressure system

• Scavenge system

• Breather/Vent system

Pressure System

• The pressure subsystem supplies the correct amount of clean lubricating oil at the proper pressure and temperature to all of the bearings and gears.

• It consists of the oil tank, the pressure pump, the pressure relief valve, the main oil filter, the oil cooler (hot-tank systems), the bearing filters, and the oil jets.

Scavenge System

• The scavenge subsystem picks up the oil after it has performed its lubrication and cooling functions and returns it to the oil tank where it can be re circulated through the system.

• Air drawn in with the scavenge oil is separated in the tank by a de-aerator and is vented to a de-oiler.

• The de-oiler separates the air still in the oil and discharges it overboard.

• The scavenge subsystem consists of the sumps, in which oil from the bearings and gears collects, the various scavenger pumps.

• The oil cooler with its bypass valve and temperature bypass valve are in the scavenge subsystem of cold-tank systems.

Breather/Vent system

• There is a steady air-stream coming from the bearing housings. This air-stream, called breather air, becomes contaminated with lubrication oil during operation and must be de-oiled with a component called de-oiler.

• De-oilers are often attached to or inside the accessory gear box, or are part of the turbine/compressor shaft .

• After the de-oiling process, the air is blown overboard to the atmosphere.