Gantry crane is a cycle, intermittent movement of machinery. A working cycle consists of the pickup device lifting the item from the pickup site, then moving horizontally to a designated location to lower the item, followed by a reverse movement to return the pickup device to its original position for the next cycle.
Usually, gantry crane is composed of lifting mechanism (to make the item move up and down), operation mechanism (to make the gantry crane move), amplitude mechanism and rotary mechanism (to make the item move horizontally), plus metal mechanism, power device, control and necessary auxiliary device combination. The gantry cranes used in bridge construction projects can be divided into light and small lifting equipment, bridge type gantry cranes and boom type cranes according to their different structure and performance.