What Is A Chain Hoist Or A Chain Block?

A ship has various machinery and systems which needs constant monitoring and periodic overhauling. 

This heavy machinery needs to be opened up for checks and maintenance. For this, a vessel contains cranes and lifting gear; however, there are many areas where small cranes cannot be fitted, like the engine room, Bow thruster room, steering gear room etc. 

This is where manual Hoists are pretty handy and used extensively. They come in many guises and are used to successfully and safely move heavy items.

If set up and used correctly, a chain hoist is one of the easiest and most efficient ways of lifting a load.

But have you ever wondered how a small chain could easily lift a thousand kgs of load?

The first procedure is to select the correct chain block for the task, depending on the load lifted. A half-tonne chain block will be ideal if we need to raise the cylinder head of the auxiliary generator engine, which is around 400kgs.

Using a chain block of higher value is always wise, as a stuck part will draw more load than expected. 

The correct cylinder sifting tool, wire sling, and I bolt should be used.

Now comes the functioning of the chain block, which enables us to lift tons of load manually with ease. 

A standard Chain Block consists of a lifting chain, a hand chain, and a base hook. The chain block is connected to the load via the base hook. 

Lifting a heavy load is possible by using multiple larger and smaller gears in the chain hoist mechanism, which increases the mechanical force by at least a dozen times. 

When the hand chain is pulled, it turns the cog and axle, which goes through the lifting mechanism. The cog turns the drive shaft, and the gears turn the load chain sprocket.

This rotates the load chain that is looped over the load chain sprocket and lifts a load. 

Inside the lifting mechanism are multiple gears.

Larger gears move slower than smaller gears but create more force. This is why the chain hoist lifts the load very slowly.

A locking mechanism locks the load and avoids downward movement due to gravitational force when no pulling force is applied. Hence, when a load is lifted and not pulled, it will keep hanging in the air. 

What machinery and parts have you lifted with the chain block on ships? Let us know in the comments.

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About Author

Zahra is an alumna of Miranda House, University of Delhi. She is an avid writer, possessing immaculate research and editing skills. Author of several academic papers, she has also worked as a freelance writer, producing many technical, creative and marketing pieces. A true aesthete at heart, she loves books a little more than anything else.

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