Guide force moments

The so-called guide force moments are caused by the transverse reaction forces acting on the crossheads due to the connecting rod/crankshaft mechanism. These moments may excite engine vibrations, moving the engine top athwartships and causing a rocking (excited by H moment) or twisting (excited by X-moment) movement of the engine (Figure 1.16).

Guide force moments are harmless except when resonance vibrations occur in the engine/double bottom system. As this system is very

Figure 1.16 H-type and X-type guide force moments (MAN B&W Diesel)

H-type guide force moment

X-type guide force moment (b)

Figure 1.16 H-type and X-type guide force moments (MAN B&W Diesel)

difficult to calculate with the necessary accuracy MAN B&W Diesel strongly recommends as standard that top bracing is installed between the engine's upper platform brackets and the casing side for all its two-stroke models except the S26MC and L35MC types.

The top bracing comprises stiff connections (links) either with friction plates which allow adjustment to the loading conditions of the ship or, alternatively, a hydraulic top bracing (Figure 1.17). With

Valve block

Engine side

Valve block

Engine side

Hull side

Oil inlet

Air inlet

Figure 1.17 Hydraulically adjustable top bracing, modified type (MAN B&W Diesel)

Hull side

Oil inlet

Air inlet

Figure 1.17 Hydraulically adjustable top bracing, modified type (MAN B&W Diesel)

both types of top bracing the above-mentioned natural frequency will increase to a level where resonance will occur above the normal engine speed.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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