1.2 Specification of MAN DG set
Type THL5500/13800
Rated power 5500 KW
Rated voltage 13.8 KV
Rated current 287 A
Number of pole pairs 4
Power factor 0.8 (lagging)
Rated frequency 50 Hz
Rated speed 750 r/min
Phase 3 phase
Excitation brushless excitation
Dry Weight 101 ton
External dimension(L×W×H) 11,045 x 3,365 x 4,850 mm
1.3 Diesel Engine
1.3.1 General
The engine is a four stroke, single action, direct injection, gas turbo-charging, intercooler medium speed high power diesel engine.
1.3.2 Main components of the engine
1.3.2.1 Crankcase
The engine crankcases made from castiron. It is in one piece and designed to be very rigid. The tierods extend from the bottom edge of the under slung main bearing to the top edge of the frame, and from the top edge of the cylinder head to the inter mediate bottom of the frame. The bearing caps of the main bearing sare, inaddition, fastened laterally to the casing. The gear train for driving the camshaft and the vibration damper are integrated in the crankcase.
1.3.2.2 Crankshaft
The crankshaft is forged from a specials steel. It is arranged in a hanging position and has, per crank, two balance weights held by undercut bolts to balance the oscillating masses. The drive wheel for the camshaft drive consists of two segments, which are held together by four tangentially arranged screws. The connection to the locating bearing flange is effected by cap screws. The flywheel, which is made from spheroidal graphite iron, is arranged on the crankshaft flange at the coupling end. Through the fly wheel or its geared rim, the engine can be turned over during maintenance work by a turning gear.
1.3.2.3Connecting rod
The so-called marine-type connecting rod was selected for the con-rod design. The parting line is situated above the big-end bearing. Therefore, the big-end bearing does not have to be opened for pulling the piston. This has advantages for operational safety (no change in position, no new adjustments), and this construction reduces the piston removal height.
The bearing shells are supplied in a ready-to-fit condition. Thin-walled shells with a light-metal running layer are used. The bearing cap and bearing body are screwed together using undercut bolts (studs).
1.3.2.4 Cylinder liner
The cylinder liners are made from special cast iron and have a spheroidal graphite iron backing ring in the upper part. This backing ring is centered in the crankcase. The lower area of the cylinder liner is guided by the inter- mediate bottom of the crankcase. There is a so-called top land ring on the collar of the cylinder liner.
The division into three components, i.e. into cylinder liner, backing ring and top land ring, results in the best possible design with regard to resistance to deformation, reliable cooling, and ensuring minimal temperatures of certain parts.
The top land ring, which projects over the cylinder liner bore hole, has a combined effect with the set-back piston crown of the stepped piston, in that coke deposits on the piston crown no longer touch the running surface of the cylinder liner. In this way, bore polishing, which prevents good adhesion of lubricating oil can be avoided.
1.3.2.5 Piston
Basically, the piston consists of two parts. The lower part consists of spheroidal graphiteiron. The piston crown is forged from high-quality material. The choice of material and constructional design result in high resistance to the occurring firing pressures and allow narrow piston clearances which, inturn, reduce the mechanical loading of piston rings, impede the access of abrasive particles and protect the oil film against combustion gases.
To seal the piston from the cylinder liner, there are three compression rings and one oil control ring. The first compression ring has a chrome-ceramic coating. The second and third rings are chrome plated. All rings are arranged in the wear-resistant and well cooled steel crown.
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