The main engine and shafting constitute the power core of a vessel, and their installation accuracy directly affects the vessel's vibration, noise, and operational reliability. Jiangsu Haizhongzhou Shipping Industry Co., Ltd. has accumulated extensive technical experience in shafting alignment and main engine installation.
Shafting Alignment Technology
The purpose of shafting alignment is to ensure the coaxiality of the connecting flanges of the crankshaft, intermediate shaft, and tail shaft. Haizhongzhou employs the "Rational Alignment Method" instead of the traditional "Straight Line Alignment Method." This method takes into account comprehensive factors such as hull deformation, bearing loads, and temperature effects.
The alignment procedure is as follows:
Use a laser alignment instrument to determine the theoretical centerline of the shafting
Install the shafting section by section, measuring the offset and deflection values of each flange
Adjust the height and position of intermediate bearings to achieve uniform load distribution among all bearings
Measure the actual load on each bearing using the hydraulic jack method
Tighten the flange bolts according to the specified torque and sequence
Main Engine Installation Process
Main engine installation involves multiple steps including alignment, chock preparation, and epoxy grouting. The top surface of the main engine foundation is machined to ensure flatness. Horizontal and height adjustments are performed using the crankshaft output flange as a reference. The holding-down bolts are secured with epoxy resin chocks, which provide high strength and low shrinkage after curing, ensuring the long-term stability of the main engine.
Vibration Control
Haizhongzhou has introduced torsional vibration calculation and whirling vibration analysis for the shafting to ensure that no dangerous resonance occurs at any rotational speed. On the 85,000 DWT bulk carrier project, by optimizing the position and stiffness of the intermediate bearings, the shafting vibration amplitude at full speed was reduced to below 50% of the standard limit value.
Mooring and Sea Trials
During the mooring trial phase, the main engine undergoes operational testing at various speeds to verify alarm and protection functions. During the sea trial phase, speed tests, maneuverability tests, vibration and noise measurements, and other items are conducted to ensure that the vessel's performance meets the design requirements.
Precision installation of the main engine and shafting provides the vessel with a powerful and reliable "heart."