Crown block

Drilling Equipment & Components

The crown block is the stationary pulley assembly located at the very top of the derrick or mast. It works in conjunction with the traveling block to create a block-and-tackle system that provides the mechanical advantage needed to lift heavy drillstrings and casing loads.

The wire rope drilling line is reeved (threaded) between the sheaves of the crown block and the traveling block. The number of lines strung determines the mechanical advantage—typically 8 to 14 lines for heavy loads. Regular inspection of the sheaves for wear is critical to prevent damage to the drilling line.