A rope or cable that passes from a lifting device over a block, to a second block attached to the load, and tied off at the first block. This line is double purchased. This allows twice as much load to be raised for a given effort, but the rope or cable must be pulled twice as far, so the total work done remains the same. (See Compound Arbor)

A counterweight system where the cradle travels half of the distance of the bar.

A type of manual rigging that uses blocks and suspension cables to reduce counterweight arbor travel to half of the batten supported.

A system which uses mechanical advantage to either increase the distance items can fly or the weight a system can lift.

A rope or cable that passes from a lifting device (arbor, winch, or person) over a block, to a block attached to the load, and tied off at the previous block, is double purchased. The system allows twice as much load to be raised for a given effort, but the rope or cable must be pulled twice as far, so the total work done remains the same.

A suspension system used on counterweight bars that gears the movement of a single counterweight bucket to half that of the bar itself.