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Tham khảo tài liệu 'lesson 13-the propulsion plant', ngoại ngữ, anh văn thương mại phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Lesson 13-The Propulsion Plant The ship propulsion plant denotes the whole plant that transfers to the propeller the power turned out by main engines. Marine diesel engines are generally of high rpm rpm being the short form for revolution per minute. As far as rpm is concerned it might be out of your expectation that if M. E. rpm is too high the efficiency of a propeller will be reduced on the opposite for the propeller rpm of an ocean-going vessel will normally range from 100 to 200. Therefore the propulsion plant concerns not only a matter of drive but a problem of the speed reduction and clutch. The propulsion plant in practical service nowadays mainly includes the following types 1. Direct Drive With simple and reliable construction convenient operation less energy loss during drive and high propulsion efficiency direct drive is the most common drive type and has found a wide application. In respect of direct drive the shaft system is directly connected with M. E. thrust shaft and both of them obtain the same rotating direction. Comparatively speaking direct drive is suitable for a lowspeed diesel engine. 2. Gear Drive The merits of gear drive are as clear as daylight for M E. rpm will be free from the low rpm limitation of a propeller after speed reduction by means of a gear and better Fig. 13.1 1-flywheel 2-intermediate shaft 3-stern shaft 4-propeller propulsion efficiency can thus be maintained. The only trouble with gear drive is that the size and weight of a reduction gearbox will inevitably and correspondingly be increased accompanying the steady increase of M. E. power. As a result of this its manufacture process will run into difficulty since the maximum diameter of a gear for a 35-50 kW reduction unit may be as large as over 5 meters. With regard to gear drive there may be a variety of arrangement patterns such as single-screw and single-rudder twinscrew and twin-rudder twin-engine incorporation with one gearbox etc. With relation to reduction gear .
