outward, and thus releasing the counterweights upon arbor impact at the end of its travel. A new type of arbor was introduced by Thern Stage Equipment in 2010. It is referred to as a front loading counterweight arbor. This arbor has shelves and a gate to secure the counterweights in the arbor. Spreader plates are not required with the front loading arbor. The arbor counterweights are loaded from the front, rather than from the sides. Counterweight arbors are commonly between 8 and 12 feet in length and can often support stacks of weights between 1500 and 2400 pounds, or beyond. In order to avoid unreasonably tall counterweight stacks at high capacity line sets, arbors may employ more than one counterweight stack. Such arbors use multiple-width top and bottom plates with a tie bar and pair of connecting rods provided at each counterweight stack. Counterweight rigging systems use either tracked or wire-guided arbor guide systems. The tracks or wire guides limit lateral movement of the arbors during arbor travel. Wire-guided systems have lower capacities and are not in common use. In addition to guiding the arbors, a tracked counterweight system is provided with bump stops at arbor high and low trim that establish the limits of an arbor's travel. A tracked guide system is sometimes referred to as a T-bar wall, as the tracks are commonly made of steel T-sections. Aluminum arbor guide tracks are a relatively recent alternative, often using a J profile, instead of a T profile, to facilitate system installation. Hoists Hoists of various types are used in manual automated rigging systems. The terms hoist and winch are often used interchangeably in theatre jargon. Hoists are generally assumed to be motorized unless "manual" is used as a descriptor. Manual hoist Manual hoists, or hand winches, are typically composed of a drum, gear box, and crank (operating handle). A worm gear is commonly used to provide mechanical advantage as the crank is turned, which coils a single line around a smooth or helically-grooved drum. The drum line is connected to the lift lines with a clew, triangular plate with holes used for line terminations. From the clew, the lift lines run over a head block and loft blocks down to a batten. The clew may be wire-guided to limit lateral play. Drill-operable hand winches permit the handle to be removed so that an electric drill may operate the hoist.