The course of freight car knot is to pull one end of a rope into a circle, and the rope end is parallel to the main rope, then take the head of another rope and pass it under the circle of 1, then wrap it around and pass through the circle, and tighten it.

A truck is a commercial vehicle designed and equipped mainly for carrying goods, whether it can tow a trailer or not. Large trucks are special flat cars for transporting large and heavy goods, such as large machine tools, generators and steam turbine rotors, steel rolling equipment, transformers, chemical synthesis towers and complete sets of equipment. Its load capacity is larger than that of ordinary flat cars, and its self-weight is also larger, so there are more axles to adapt to the limit of allowable axle load and load per linear meter of the line.