Definitions for "Head Block"
Keywords:  arbor, sheave, pulley, grooved, lift
Multiple sheave block mounted on the Head Block Beam above a counterweight arbor that changes the direction of lift and operating lines.
A large sheave, grooved for support lines and hauling lines and attached to the support steel directly above the fly rail.
A large rectangular decorative block similar in use to the corner block. While the corner block is always square, head blocks are larger, highly detailed and milled in unusual shapes. Used at the tops of doorways and windows. See Detail 49.