POWER PACK
Specialty of WDG/3A loco engine
1. 251-B Up rated type
2. ‘V’ type cylinder arrangement
3. Total 16 cylinder
4. Four stroke cycle
6. High speed
7. Water cooled
8. Force lubricated
9. Super charged
10. Quality governor
Main parts of engine block
1. Cylinder blocks
2. Main crank shaft
3. Cylinder liner
4. Piston rings & connecting rod
5. Camshaft & camshaft gear
6. Push rod
7. Main Bearing
8. Cylinder liners
9. Cylinder head & valve
10. Piston rings & connecting rod
11. Fly wheel
12. Rocker arm assembly
13. ‘V’ gallery
14. Vibration damper
15. Exhaust manifold
Description
In WDG-3A locomotive 251-B up rated engine is fitted. Cylinder block of these engine posses by sixteen cylinders, eight on each side (left and right) and arranged in “V” shape. This cylinder block is made of steel plates welded together and mounted on crankcase with the help of nuts and bolts. This cylinder block support main crank shaft and two cam shaft inside. Engine block having V gallery, it is called air intake manifold, each cylinder is connected to manifold with the help of inlet elbows. Each cylinder has a cylinder liner, piston and connecting rod, cylinder head with two inlet and exhaust valves, one fuel injector and rocker arm assembly.
In engine block a main crank shaft made up of steel alloy is fitted in one piece. It has 9 main bearings and 8 crank pins. On every crank pin two connecting rods are connected, the other end of connected rod is connected with Piston with the help of piston pin. Fly wheel is fitted on one end of the main crank shaft and vibration damper on the other end. On fly wheel end main generator is connected, this end is called power take off end and opposite end is called free end.
Two cam shafts are provided in engine block on both sides, each shaft has made of four pieces and each piece has two pairs of three lobes. Camshaft is driven by its gear (104 teeth) matching with split gear (52 teeth). Split gear is provided on main crank shaft at power take off end. In 3 cam lobes, left side cam operate inlet valves, right side cam operate exhaust valves and middle cam operates fuel injection pump.
Each cylinder has a piston which is made of Aluminum with steel cap, piston has two ends, top end is called piston crown and bottom end is piston body. Piston body has three compression rings and two oil scraper rings. Piston is connected to connecting rod with piston pin. Oil grooves are provided to cool the piston with lube oil.
Cylinder liner made of cast iron is fitted in each cylinder. Honey combings are provided on the inside surface of the liner for lubrication purpose. Liner is covered with water externally, ‘O’ ring is provided in between liner and cylinder block to avoid water leakage.
In each cylinder head two inlet valve, two exhaust valve, one fuel injector and rocker arm assembly is fitted. Cylinder head kept cool with water. Cylinder head is covered with Tapped cover. Inlet valve is connected to “V” gallery through inlet elbows. Exhaust valve is connected to exhaust manifold through exhaust elbows. Rocker arm assembly operates inlet and exhaust valve. Inlet valve, exhaust valve and fuel injection pumps are operated according to their valve timing.
Crank case sump is provided below engine block, which called lube oil sump. Crank case explosion door, crankcase exhauster motor and OSTA are provided to safeguard engine block.
Working:
When main generator works as a motor and main crank shaft rotate than piston gets movement through crank pin, connecting rod. Cam shaft rotate with the help of cam shaft gear and inlet valve, exhaust valve, fuel injection pump are operated according to valve timing.
When piston moves from TDC to BDC inlet valve will open and fresh air from “V” gallery enter in cylinder it is called suction stroke.
When piston moves from BDC to TDC that time inlet and exhaust valve remain closed and air gets compressed and temperature raised is called compression. Before reaching to TDC fuel inject in the cylinder through fuel injector.
Fuel starts burning and compels the piston to move from TDC to BDC which makes connecting rod, crankpin to rotate main crank shaft, it is called power stroke.
When piston at BDC exhaust valve will open and piston moves from BDC to TDC and piston pushes the exhaust gasses to evacuate through exhaust valve, exhaust elbow, manifold and TSC chimney.
Before piston reaching to TDC inlet valve also opened and fresh air enter in cylinder to push exhaust gasses and makes piston to cool, it is called scavenging. Time interval, when Inlet and exhaust valve are in opened condition is called crankshaft overlap period.
All 16 cylinder power firing order is 1-4-7-6-8-5-2-3 from Right to left for steady rotation of main crankshaft.
Governor is provided for controlling of fuel oil supply. Cooling water system is provided to cooling of diesel engine. Lube oil system is providing to lubricate diesel engine equipment. TSC is provided for diesel engine super charging.
