Gooseneck semi-trailer is also widely used to carry cargo, suitable for a variety of mechanical equipment, large-scale objects, highway construction equipment, large tanks, power plant equipment and machinery of all kinds of steel transport. Series semi-trailer has flat, concave beam and tire exposed structure, longitudinal beam adopts flat or gooseneck type, its frame is ladder type, longitudinal beam section is I-shaped, with high stiffness, high strength characteristics. The main plane of the frame freight platform is low, which ensures the stability of transportation and is suitable for carrying large-scale equipment and steel products of various construction machinery. A three-axis balanced flexible rigid suspension is used. A mass balance block is installed between the front and rear leaf springs. The deflection of the front and rear leaf springs can be changed equally and the force of the rear axle can be equalized. It has a wide range of uses, high efficiency and high speed. The whole vehicle adopts advanced computer aided design software to optimize the design flexibly and diversified. The bearing surface of the frame is designed according to the user's requirements to meet the transportation of various special goods. Liangshan Yangjia Trailer Factory is a designated production enterprise of special automobiles in the state announcement. The company's leading products are trailers, semi-trailers, full trailers, low-flat semi-trailers, special vehicles, semi-trailer dump trucks, barn trucks, tank trucks, dump trucks, vehicle transporters, powder material transporters, van trailers, barn semi-trailers, barn semi-trailers, etc. High-hurdle trucks, barn trailers, cement bulk trucks, light special semi-trailers, concrete mixers, low-flat-plate special trucks at harbour terminals, special coal-handling trucks, oil tankers, asphalt special trucks, cement bulk trucks, cement mixers, container semi-trailers, low-flat-plate transport trucks, refitting trucks, containers, storage trucks Lengthening and widening vehicles, high and low flat, special operation vehicle and so on six big series.