Needle bearing blocks

Needle roller bearings, also known as roller bearings, are among the highest-performance bearings for high-quality, heavy-duty blocks. Compared to ball bearings, they have significantly larger contact surfaces, which enables them to withstand higher loads whilst ensuring smooth, ‘rolling’ operation.

Thanks to these properties, needle roller bearings combine the advantages of plain bearings and ball bearings: they are particularly robust, like plain bearings, whilst also running smoothly, like ball bearings.

Needle roller bearing blocks are therefore primarily used in applications involving very high working loads, where maximum load-bearing capacity and reliable operation are crucial.

Absolutely not! Standard pulleys are usually fitted with plastic sheaves designed for use with rope.

The steel wires contained in wire ropes place significantly greater demands on the material of the sheave. Plastic sheaves cannot withstand this stress and would be damaged. Therefore, only pulleys specifically designed for wire ropes should be used.

A block will only function reliably if it is fitted in such a way that it can move freely and align itself automatically with the direction of pull of the rope or wire rope. This is the only way to ensure that the load runs smoothly over the sheave.

If, on the other hand, the block is fitted in such a way that it cannot align itself freely, there is a risk of it becoming jammed. In this case, the loaded rope may press against the block’s jaw, causing damage to the block. In the worst-case scenario, the rope becomes trapped between the suspension and the sheave and jams.

Such jamming poses a significant safety risk to the vessel and its crew. It is therefore essential that every block installation is carefully planned, correctly carried out and regularly inspected.

Damage to blocks is often caused by overloading, for example when they are undersized. So-called ‘patent halyards’ or the use of shackles instead of a suitable swivel can also lead to problems.

If a block is used without a swivel, even though a swivelling suspension is required, the sheet can force the block to rotate. As this movement cannot be counteracted, the sheet no longer runs smoothly over the sheave but presses against the side plate.

The forces at work in this situation lead to severe deformation and, in the worst case, can completely destroy the block. For this reason, blocks with swivels should be used whenever possible.