Snatch Blocks

[TowZone]

The snatch block is a common tool for nearly every operator.  But how many of us know the manufacturer’s recommended use, maintenance and inspection instructions?  Below are the highlights for the Gunnebo-Johnson snatch blocks:

Stay within the safe working limits of the block regardless of the strength of the wire rope being used.  The working limits apply to loads in uniform direct tension and not shock loads. Working limits apply to new products as they are shipped from the factory.  The age, type of service and environmental conditions can affect the capacity of a snatch block over time.  Standard blocks are not designed to be immersed in either fresh or salt water.

Snatch blocks are designed to be lubricated with either a sodium or lithium based grease.  Bronze bushed blocks and sheaves need to be lubricated every 8 hours of continuous usage or at least every 14 days with intermittent use.  Roller bearing blocks and sheaves can go 24 hours of continuous use before needing grease and the same 14 days with intermittent use.  Swivels follow the roller bearing lubrication schedule.

Wear is a fact of life and will eventually affect the load the snatch block is able to carry so regular and frequent inspection is needed.

 

• Permanent deformation of any part is a clear indication of overload and must be taken out of service and replaced.

 

• Swivel end play of more than 1/16” is a danger sign and must be removed from service immediately.

 

• Spreading side plates are caused by overload and must be removed for repair.

 

• Looseness in the side plates are a sign of loose retaining nuts.

 

• Sheave alignment issues such as wobbly sheaves are caused by bearing wear.

 

• Sheave groove wear are ridges in the sheave caused by rope wear. These can prematurely reduce wire rope life and the sheave should be replaced.

 

• Hook latches are designed to hold loose rigging under slack conditions.  Any damaged latches should be replaced.

• Hook deformation with a crack, gouge or distortion needs to be removed from service immediately.