Vertical truss train liquid loading and unloading arm

The invention relates to a train tanker liquid loading and unloading device, in particular to a vertical truss train liquid loading and unloading arm. The vertical truss train liquid loading and unloading arm is formed through corresponding assembling of a rail body, a walking trolley, a balance system, an air returning hose, a vertical connecting pipe, a seal cap, a telescopic vertical pipe, an outer arm, a middle connecting pipe, a rotating arm, a vertical pipe lifting motor set, a trolley walking motor set, rotating joints, a liquid phase connector and a chain wheel assembly; and the rotating arm, the middle connecting pipe, the outer arm, the vertical connecting pipe and the vertical pipe are connected together through the four rotating joints to form a liquid phase pipeline, the liquid phase pipeline is connected with a liquid phase fixing pipeline through the liquid phase connector, the outer arm is linked with the walking trolley to press the seal cap on a train tank opening, and the vertical pipe lift