Dual-rail self-propelled trolleys are widely used in the pre-treatment electrophoretic coating lines of vehicle frames or bus bodies. They consist of steel structures, running tracks, power supply systems, load-carrying car groups, transfer trolleys, lifting fixtures, and electrical control systems. With a lifting capacity ranging from 3000 KG to 50,000 KG and a running speed of 0–20 m/min, they support both manual and automatic control modes.