 |
||||
|
Design features The C25:33 is based on a compact and stiff nodular iron frame. The charge air receiver, lube oil channel and coolant transfer channel are incorporated in the casting to eliminate pipework. A continuous grain flow forged steel crankshaft that has steel plate balance weights and runs in the latest bearing material allows the cylinder center distance to be kept the same as the K series, in the interests of compactness and rigidity. Full power can be taken off either end of the crankshaft, and an additional main bearing allows single-bearing alternators to be used.  A key feature is the cylinder unit concept, in which a complete liner, piston assembly, jacket and cylinder head can be drawn as a unit. The components are clamped together by the cylinder jacket and held down by four cylinder head bolts. A duct transfers air, exhaust and cooling water to and from the head, and for speed of servicing the duct for each cylinder unit is connected to its neighbors by quick-couplings. The cylinder liner and water jacket combination is of the “open-deck” type, designed for very intensive cooling and high strength without stress raisers in the critical top-end zone. The piston uses a steel crown carrying three rings, and a nodular cast iron skirt. This, in conjunction with the anti-polishing ring at the top of the liner, the chrome-ceramic piston ring coating and the special honing structure of the liners, gives a long life with low and controlled oil consumption. A three-part connecting rod has been developed, enabling the upper part to be detached when drawing pistons without disturbing the big end bearing. Fuel pumps are mechanical, one per cylinder, and of the closed end design for high pressure, with a simple two-step electronic timing feature. The new C-engine does not have “common rail” injection because it is not seen as having an advantage in the generator-set applications typical of the new engine. The engine incorporates an all-radial uncooled turbocharger, which can be mounted at either end of the engine. Two-stage cooling of the charge air with electronic temperature control, combined with a high-speed electronic governor allow a rapid response to load changes with minimum smoke under various load and speed conditions. Plug-in components are easy to exchange, with a minimum of joints, which is important for eliminating leakages. Integration has not, however, been carried to extremes. For example, the lube oil heat exchanger is mounted on the front-end module, but incorporates a backing plate which could in principle be eliminated. By fitting it, a servicing advantage is won, as the cooler can be quickly detached as a unit for overhaul and pressure testing, rather than being dismantled on the engine. Other features for ease of overhaul include full use of hydraulic bolting and large crankcase doors. |
||||