Double Purchase Head Blocks

Double purchase head blocks are used when an obstruction or other limitation restricts the travel of a single purchase arbor. Used in conjunction with a double purchase arbor, this style of rigging enables the batten to travel two feet for each foot of arbor travel.
A standard Series 50, 51, or 55 head block assembly is modified by the incorporation of purchase line and lift line tie-offs. Tie-off is sold separately as a factory installed modification only. Since double purchase arbors must be sized larger than single purchase arbors, the entire head block assembly must be designed to accommodate the increased load. Care must be taken to equally space lift lines in tie-off.