Power & free conveyors feature two overlapping lines: the upper one consists of the chain with the driving function, and the lower one allows the sliding of the workpiece carriers. The two lines are independent; the movement of the lower trolleys, which are idle, is made possible by the connection to the upper chain via spikes controlled by pneumatic stations. This also enables the trolleys to be stored in certain areas of the track to be picked up later. The workpiece-carrying frames hanging on different trolleys can also follow different paths on parallel lines through “orthogonal shifts”. That allows storing them in the oven or in buffers located in the loading/unloading areas or in other sections of the line.
With this type of conveyor, it is possible to load and unload the workpieces while the load frame is stationary. Finally, the track can be split to allow the parts to access different coating booths arranged in parallel, thus managing colour changes without stops or interruptions in production. Thanks to these characteristics and despite their elaborate design, two-rail conveyors offer significant advantages in terms of production flexibility and the possibility of performing complex processing cycles even when handling parts with a considerable size and weight.