This type of carriage has the purpose of transporting large and very heavy metal structures, equipment for power plants, injection molds and casting molds. The carriages run on a steel runway rail, mounted on the floor. There is a version of polyurethane or polyamide wheels that can also be used on floors with the smooth surface of the concrete. In this case, at least two of the wheels are steerable.

Trolleys can be towed or self-propelled. The use of the latter is facilitated by the fact that no cable, power or command connection is required. This high mobility has been achieved by using batteries and radio remote control.