Bed plate


Engine Bedplate

The bed plate forms the foundation of the engine and on which the other structural component such as A-frame, all column,and Guides are mounted and it can withstand heavy fluctuating stresses from working parts.

Bedplate supports the Load of the Engine and it’s other Constructional parts and provide a base for the large mass.

bed plate

Functions of Bed Plate

It is required to transmit engine load including propeller thrust,to the ship Structure and distribute these over necessary area and ensure alignment of the crankshaft.

The bed plate collects the crankcase lube oil and returns it to the drain tank for recirculation.

It is bolted at the tank top which in turn is reinforced with thicker plate and girders.

The bed plate acts as a base and provides support to the engine structure.

It holds the Static weight of the whole Engine.

The crankshaft is so fitted in the Bedplate in the main journal Bearings.

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For a small engine one piece cast iron bed plates are common.

For large engines fabricated mild steel, longitudinal girder with cast steel transverse girders supporting the crankshaft bearing is constructed.

One important thing to be considered in the construction of Bedplate of Large Marine Diesel engine is to use materials of carbon content only upto 0.23% like Low carbon steel.

On the other hand the small Bedplate can be construed with cast iron which is required to have internal vibration damping feature to smoothen and dampen the vibration .


Since Bedplate is the base of the Engine it should be in proper order for the proper functioning of the Engine. And for that it should be regularly checked and maintenance should be carried out.

The bed plate should be inspected for the:

Cracks which may occur due to long working and loading .

Welding joints generally and also if any recent welding work has been carried out.

Being at the bottom most part of the Engine it is susceptible to corrosion also. It should be inspected for that.

Loose Frames may happen because of excessive loading or if issue with the tie rods.

The Holding down Bolt should be inspected for tightness as it hold the Bedplate with the bottom structure of the ship.

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