and cooling water were used to raise steam, which was then supplied to theunderside of the working piston.Evolution decreed that the surviving trio of low-speed crosshead enginedesigners should exploit a common basic configuration: two-stroke engines withconstant pressure turbocharging and uniflow scavenging via a single hydraulicallyoperated exhaust valve in the cylinder head.All the three companies now offer electronically controlled (MAN DieselME, Mitsubishi Eco-Engine and Wärtsilä RT-flex) versions alongside their traditionalcamshaft-controlled designs (respectively, the MC/MC-C, LSII/LSEand RTA series). The ME and RT-flex engines with electronic control of fuelinjection and exhaust valve operation are increasingly popular and well establishedin service, but some operators retain a preference for the mechanicallycontrolled models.Current programmes embrace mini-to-large bore models with short-, longandultra-long-stroke variations to match the propulsive power demands andcharacteristics of most deep sea (and even some coastal/short sea) cargo tonnage.Installations can be near-optimized for a given duty from a permutationinvolving the engine bore size, number of cylinders, selected output rating andrunning speed.Bore sizes range from 260mm to 1080mm, stroke/bore ratios up to 4.4:1,
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