The turbocharger employs a self-contained lubrication system utilizing ball and roller bearings. The bearings are housed within a casing, the bottom of which acts as an oil sump. A gear pump, driven directly by the turbine shaft, draws oil from this sump and delivers a pressurized jet of oil directly to the bearings. Both the turbine and blower sides utilize this identical system. A sight glass allows for oil level monitoring, while drain and fill plugs facilitate maintenance. This design is typically found in axial flow turbochargers.

The blower side employs a double-row ball bearing to accommodate axial thrust loads and axially locate the turbocharger rotor assembly. The turbine side utilizes a single-row ball bearing, allowing for thermal expansion of the rotor shaft. Leaf springs are incorporated between the outer race of the bearings and the housing to dampen vibrations and reduce bearing chatter, extending bearing life.

Advantages of the Lubrication System

• The gear pump-driven system ensures better lubrication at increased speeds.
• The initial cost of the system is low, as it does not require external components like coolers or filters.
• The pump's location at the aft end of the shaft makes inspection and maintenance straightforward.
• The system operates independently of the main engine lubrication system, reducing complexity and risk of cross-contamination.
• Turbine oil, with superior thermal and lubricating properties, enhances performance and reliability.

Disadvantages of the Lubrication System

• The system provides poor lubrication at low speeds due to the gear pump's dependence on turbine shaft rotation.
• Oil in the sump must be renewed periodically to maintain performance.
• If the attached gear pump fails, it can lead to insufficient lubrication, causing damage to the turbocharger bearings.
• The use of turbine oil, while beneficial, adds to operational costs due to its premium quality and price.