Starting of an Auxiliary Diesel Engine
The auxiliary diesel engine is mostly started with the help of compressed air,depending upon the size of the engine. Other means of starting includes Electric start(battery) and air motor(engaged in the flywheel). The most common method is the use of compressed air. The lay out for starting the auxiliary engine is given below.
Before starting the auxiliary engine, the following safety checks must be carried out:
1. Turning gear disengaged(if available).
2. Lubricating oil sump level normal
3. Turbocharger oil level( both turbine & blower)side normal
4. Lubricating oil priming pump running.
5. Fuel oil/diesel oil booster pump running.
6. lube oil, cooling fresh water, fuel oil pressure normal.
7. Rocker arm tank level normal.
8. All valves in compressed air line open to the engine.
Referring to the above starting diagram of an auxiliary engine, the" main air" from the main air bottle arrives at the air starting valve. There is a tapping from the main air starting line, "pilot air" going to the starting air distributor. When the engine rotates, the camshaft also rotates which in turn rotates "the starting air distributor cam". This cam is designed as per the firing order of the engine such that, the distributor rotates and lets the pilot air to the particular unit. The pilot air reaches on top of the air starting valve, opening it, in turn making the long awaited main air to let inside the combustion chamber. The main air which is at 30 bar, pushes the piston down making the crankshaft to rotate. This leads to continuous rotation of the crankshaft making the engine to achieve the minimum r.p.m at which firing of the injected fuel takes place. When the engine picks up on fuel, the air is cut off and drained. Thus the auxiliary diesel engine is started with the help of compressed air.
In the next article, we will take up the study of the various valves mentioned in the starting air systems namely master air starting valve, cylinder valves and so forth.