MAN B&W Controllable pitch propeller. Lubricating oil system. VB and VBS
Lubricating oil system, VB
The VB propeller and stern tube have a common lubricating oil system, fig. 10.
In order to prevent sea water penetration the system is kept under static pressure by the gravity tank placed above normal load water line in accordance with the stern tube seal manufacturer’s recommendations.
Because of pumping effect in the propeller hub during pitch changes, oil is circulated through propeller equipment and oil tank. Non return valves in hub and at pitch control rod secure that the oil flow to the hub passes the stern tube journal bearings and further along the chromium steel journal to the blade actuator mechanism.
Fig. 10. VB lubricating oil system
The return oil flows along the pitch control rod back to the lub oil tank.
The propeller hub is fitted with 2 plugs for draining and venting during docking.
The pitch control rod is lubricated with grease where intermediate shafts are fitted.
Lubricating oil system, VBS
As with the VB equipment the stern tube and hub lubrication is a common system. The stern tube is therefore kept under static oil pressure by a stern tube oil tank placed above sea level, see fig. 7.
All MAN B&W propeller equipment with seals of the lip ring type operates on lub oil type SAE 30 – usually the same type of lubricating oil as used in the main engine and reduction gear.