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ENGLISH FOR MARINE ENGINEERS – 18.4.2011

ENGLISH FOR MARINE ENGINEERS – 18.4.2011. 2010/2011. Valve operating gear , p. 40, ex . 5. The cams are carried by the camshaft. … the rotation of the camshaft on a two-stroke engine proceeds at the same speed as the crankshaft. Chain drives have light weight, narrow width, and flexibility.

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ENGLISH FOR MARINE ENGINEERS – 18.4.2011

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  1. ENGLISH FOR MARINE ENGINEERS – 18.4.2011 2010/2011

  2. Valveoperatinggear, p. 40, ex. 5 • The cams are carried by the camshaft. • … the rotation of the camshaft on a two-stroke engine proceeds at the same speed as the crankshaft. • Chain drives have light weight, narrow width, and flexibility. • However, they elongate in service as a result of wear … • …a gear train has higher weight and cost. • In case of misalignment of gear wheels, shock loading will result … • The cams are expanded onto the camshaft in the correct position and either heat or hydraulic means can be used.

  3. Valveoperatinggear, p. 40, ex. 5 • … allowing for adjustment and so that the cam can be replaced if necessary. • … because contamination by fuel oil leaking past the fuel pumps is possible. • …, elongation of the chain results in retarded timing of the fuel pumps and exhaust valves. • …, retiming is necessary.

  4. Valveoperatinggear, pp. 40-41, ex. 6 • Are driven • Depending • Are located • Rides • Rises • Pushes • Mounted • Distributes • Is called • Be maintained • Be adjusted • Are needed

  5. Valveoperatinggear, pp. 40-41, ex. 6 • Is operating/operates • Is supplied • Is trapped • Acts • Is replaced • Rocks • Are made

  6. turbocharging, p. 42, ex.1 A two stroke crossheadengineneedsairaboveatmosphericpressure. Turbochargingwas used forthefirst time in the 1950s. Beforethenmechanicallydrivencompressors or reciprocatingcompressorswereused. As a result, engineefficiencywaslower. Enginepowerhasincreaseddramatically. Today's enginesproduce 4 timesthepowercompared to oldengines. This is possiblebecauseofimproved materials and manufacturing techniques, but also turbochargers.

  7. turbocharging, p. 42, ex.1 Useful energy is provided by the burning of the fuel but also depends on engine efficiency. An important question concerning turbocharging is how much air we need in the air-fuel mixture for 100% burning of fuel. The answer is we need 14 kg of air for 1kg of fuel. Air is neededforscavengingandcoolingofthelinerandexhaustvalve.

  8. turbocharging, p. 42, ex.1 Air must be compressed at 2.5 bar to supply the required oxygen. Fuel oil consumption in modern marine engines, according to manufacturers’ quotes, can be between 165 and 175 g/kWh. The turbocharger works on wasted heat, which amounts to about 7 % of the total energy to drive the turbine, which compresses the air. A turbocharger can rotate at a maximum speed of 10000 RPM. When the engine is running at low RPM, we may use an auxiliary blower for supplying the engine with fresh air.

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