Features of Rail-Mounted Container Gantry Cranes

A rail-mounted container gantry crane (RMG) is a container crane mounted on two rails.

The main features of rail-mounted container gantry cranes are as follows:

① Low lifting speed and high trolley speed. Based on the requirements of container yards, the lifting height of rail-mounted container gantry cranes is determined based on stacks three over four or four over five. Because the lifting height is low, the lifting speed is correspondingly low. However, container yards are generally long along the track, so to achieve a certain level of productivity, the trolley speed is high.

② The trolley speed can be determined based on the bridge span and the overhang at both ends. When the span and cantilever length are small, the trolley speed and productivity requirements can be relatively low. When the span and cantilever length are large, the trolley speed can be increased to meet productivity requirements.

③ When the span exceeds 40m, the trolley will deviate during high-speed operation due to the different resistance of the gantry legs on both sides. To address this, a synchronization device is installed to synchronize the operating speeds of the two gantry mechanisms through an electrical control system.

④ To meet higher operating requirements, the electric drive control system uses a thyristor DC or AC speed control system to achieve better speed regulation and control performance. The electrical control system can also use conventional AC eddy current speed control or AC stator voltage regulation speed control system. For the electrical control system of the high-speed trolley running mechanism, a thyristor DC or AC speed control system with electrical braking or an AC stator voltage regulation speed control system is usually used to avoid the use of conventional electric drive systems that rely on brakes when stopping, which may cause a huge impact on the entire machine.