Q.1) Describe the general layout of internal lubricating oil system for an auxiliary engine?
The lubricating oil system is based on wet sump lubrication. All moving parts of the engine are lubricated with oil circulating under pressure in a closed built-on system. The lubricating oil is furthermore used for the purpose of cooling the pistons.
System Flow
The lubricating oil pump draws oil from the oil sump and presses the oil through the cooler and filter to the main lubricating oil pipe, from where the oil is distributed to the individual lubricating points. From the lubricating points the oil returns by gravity to the oil sump.
The main groups of components to be lubricated are:
1.Turbocharger
2. Main bearings, big-end bearing etc.
3 .Camshaft drive
4 .Governor drive
5 .Rocker arms
6 .Camshaft
1) Turbocharger: For priming and during operation, the turbocharger is connected to the lub. oil circuit of the engine, the oil series for bearing lubrication. The inlet line to the turbocharger is equipped with a fixed throttle in order to adjust the oil flow and a non-return valve to prevent draining during stand-still. The non-return valve has back-pressure function requiring a pressure slightly above the priming pressure to open in normal flow direction. In this way overflooding of the turbocharger is prevented during stand-still periods, where the prelubricating pump is running
2) Main bearings: Lubricating oil for the main bearings is supplied through holes drilled in the engine frame. From the main bearings it passes through bores in the crankshaft to the connecting rod big-end bearings. The connecting rods have bored channels for supply of oil from the big-end bearings to the small-end bearings, which has an inner circumferential groove, and a pocket for distribution of oil in the bush itself and for supply of oil to the pin bosses and the piston cooling through holes and channels in the piston pin. From the front main bearings channels are bored in the crankshaft for lubricating of the pump drive.
3) Camshaft drive: The lubricating oil pipes, for the camshaft drive gearwheels, are equipped with nozzles which are adjusted to apply the oil at the points where the gear wheels are in mesh.
4) Governor drive: The lubricating oil pipe and the gearwheels for the governor drive are adjusted to apply the oil at the points where the gear wheels are in mesh.
5) Rocker arms: The lubricating oil to the rocker arms is led through pipes to each cylinder head. It continues through bores in the Cylinder head and rocker arm to the movable parts to be lubricated at rocker arms and valve bridge. Further, lub. oil is led to the movable parts in need of lubrication.
6) Camshaft: Through a bore in the frame Iub. oil is led to the first camshaft bearing and through bores in the camshaft from where it is distributed to the other camshaft bearings.
Q2.) Describe the essential components of the system?
Lubricating Oil Pump
The lubricating oil pump which is of the gear wheel type, is mounted on the front end of the engine and is driven by means of the crankshaft through a coupling or a gear wheel.
The pressure regulator forms part of the lubricating oil pump. Adjustment of the oil pressure is done by removing the cap nut and turning the adjusting screw.
Pre-lubricating Pump
As standard the engine is equipped with an electric-driven prelub. pump mounted parallel to the main pump. The pump must be arranged for automatic operation, ensuring stand-still of the prelubricating pump when the engine is running, and running during engine stand-still in stand-by position. Running period of the prelubricating pump is
preferably to be continuous. If intermittent running is required for energy saving purpose, the timing equipment should be set for shortest possible intervals, say 2 minutes of running, 10 minutes of stand-still, etc. Further, it is recommended that the prelub. pump is led from the emergency switch board thus securing that the engine is not started without prelubrication.
Lubricating Oil Filter
The lubricating oil filter is a double filter which is generally used with only one filter chamber being in operation, the other filter chamber being stand-by. If the filter chamber in operation needs to be serviced, the operation can be switched to the other filter chamber without any interruption in lubricating oil supply to the engine. Servicing is generally restricted to replacing of the paper cartridges, cleaning of the radial mesh insert and inspection of sealings , the latter to be replaced if damages observed.
Each filter chamber is equipped with 1 or 2 replaceable paper cartridges of fineness 10-15 microns. In the centre of each filter chamber a filter basket (central element) is situated. This filter basket is acting as a safety filter, having a fineness of about 60 microns. During operation an increased pressure drop across the filter will be observed as dirt particles will deposit on the filtration surfaces of the paper cartridges and thus increase the flow resistance through the fitter.
If the pressure drop across the fitter exceeds 2.0 bar, a release valve will open and by-pass the 10-15 microns filter element, and the engine will run with only the 60 microns safety filter. To ensure safe filtering of the lubricating oil, none of the by-pass valves must open during normal service and the elements should be replaced at a pressure drop across the filter of 1.5 bar.
Thermostatic Valve 
The thermostatic valve is designed as a T-piece with the inlet in the cover (A) under which the thermostatic
elements are located.
The outlet to the engine (by-passing cooler) is marked (13) and outlet to the cooler is marked (C). In the
warming up period, the oil is by-passing the coder. When the oil worn the engine reaches the normal
temperature a controlled amount of oil passes through the cooler.