Abstract: An apparatus for use in carrying a load particularly in theatrical performances comprising a supported guide rail, with a first and second carriage movably mounted on the guide rail, the first carriage being adapted to carry a movable lift line for carrying the load, and a compensator system linking the first and second carriage and being arranged such that on movement of the first carriage or the second carriage, the other carriage moves in the same direction and the second carriage moves a shorter distance than the first carriage. Lifting and lowering of the load may be achieved independently of travel along the rail and a load may be transported at a constant height.