Finnøy Hovedbrosjyre - version 8

2 SPEED GEARBOX The 2 speed gearbox are used on vessels with large difference in power need. This configuration has the following advantages: - Two different propeller speeds at constant engine speed - The propeller can be operated at optimal speed both at high and low load - Minimized zero pitch loss at “low gear” - Minimized propeller noise at “low gear” - Fuel saving at low load High gear - C1 is engaged, C2 is disengaged - Can give full engine power to propeller - Excess power to shaft generator Low gear - C1 is disengaged, C2 is engaged - Reduced engine power to propeller due to lower propeller speed - Excess power to shaft generator In addition to the 2 SPEED gearbox the ship can have floating frequency. Allowing the engine speed to be lowered also in “generator mode”. Variations in engine speed are corresponding with 60-50 Hz from the shaft generator Below are an example from the vessel “SMARAGD” A combination of 2 SPEED gearbox and floating frequency gives them a variation of propeller speed between 148 and down to 100 rpm. Which allows optimal propeller speed in the full operation range. Speed selection Engine speed (rpm) Propeller speed (rpm) Approx. propeller power at max. pitch (kW) High gear(reduction 4,05:1) 600 (60 Hz) 148 4000 500 (50 Hz) 123 2150 Low gear (reduction 5,0:1) 600 (60 Hz) 126 2000 500 (50 Hz) 105 1150