Tbd 645 Series

Introduced in 1993, the Deutz 645 engine is a 330 mm bore/450 mm stroke design produced in six-, eight- and nine-cylinder in-line versions to serve propulsion plant and genset drive requirements from 2550 kW to 4140 kW at 600/650 rev/min (Figures 20.1 and 20.2).

The monobloc crankcase is made of ductile cast iron, the side walls extending far down below the crankshaft centreline. It is provided with suspended crankshaft bearings, large service access openings and continuous mounting rails. The main bearing caps are bolted in the lower part to either side of the crankcase to ensure high crankcase stiffness. The crankshaft is of heat-treated forged steel and machined on all surfaces. The main and big end bearings are designed as grooved bearings. The die-forged diagonally split connecting rods feature a toothed joint and a stepped small end. The shank cross-section is of double-T configuration, with cooling oil supplied to the piston through a bore.

A forged steel crown and a forged aluminium body form the composite piston. Three compression rings are carried in hardened grooves in the crown, and one oil control ring in the body section. All the piston rings have a chromium-plated working surface.

The thick-walled centrifugally cast cylinder liner is salt bath-nitrided to minimize wear. A separate water guide ring with four passages to the cylinder head ensures intensive cooling of the upper liner section.

The ductile cast iron cylinder head is of double-bottom configuration and arranged to accommodate two inlet and two exhaust valves, each fitted with Rotocaps. The exhaust valves are installed in easily removable cages and can be exchanged without draining the cooling water. The water-cooled seat insert is armoured with Stellite F; the valve cones are

Figure 20.1 Cross-section of Deutz 645 engine. Note how the main bearing caps are bolted in the lower part to both sides of the crankcase, imparting high crankcase stiffness armoured with Stellite 12 or, optionally, with Colmonoy 56 for heavy fuel operation.

Valve timing is actuated by a one-piece camshaft with hydraulically pressed-on individual cams, roller tappets, hollow pushrods and forked

Figure 20.2 Deutz 645F engine installed in a Dutch trawler

rocker arms. The camshaft can be removed from the side to simplify servicing procedures.

A L'Orange fuel injection system comprises individual fuel injection pumps, very short injection lines ducted through the lower part of the cylinder head, and injectors which are cooled by the engine lube oil system. The injection pump element and roller tappet are separated by a lip seal. The commencement of delivery is adjusted according to the load applied.

Single-stage pulse turbocharging based on ABB turbochargers is associated with a two-stage charge air cooler allowing preheating of the air under low load conditions.

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