Semi-trailer is the most common type of transportation vehicle. It has strong carrying capacity and large loading capacity. Almost all materials can be transported by semi-trailer.
Classification of semi-trailer
Semi-trailers can be included normal semi-trailer and special semi-trailer.
Normal semi-trailer included:
1. Container and bulk cargo semi-trailer: skeleton trailer, flatbed trailer, side wall trailer etc.
2. Construction semi-trailer: Low bed trailer, dump trailer etc.
3. Tanker semi-trailer: bulk cement tanker trailer, fuel tanker trailer, aluminum tanker trailer etc.
4. Gas tanker semi- trailer: LPG tanker trailer, LNG tanker trailer, LCO2 tanker trailer etc.
Special semi-trailer included:
SPMT (Self-propelled modular transporter) trailer, wind blade trailer, log wood trailer etc.
Structure of semi-trailer
The semi-trailer is mainly composed of cargo body, chassis, Landing gear, suspension, axle, electric system and tool box etc.
Chassis: The welded longitudinal beams, through beams, and profiled steel members made of steel plates for vehicles are assembled and welded together. They are space-frame structures used to support the main components of the load, installation of Kingpin, suspension, and Landing gear.
Landing gear: The Landing gear for supporting the front load of the semi-trailer after being lifted off the hook is composed of a base, a lever transmission mechanism, an inner square tube, an outer square tube, a gearbox, a steering handle and the like. There are two types of single-action and linkage. Each of the single-action legs has a handle, while the linkage has only one handle.
Suspension: The suspension is used to transmit load and damping mainly includes brackets, tie rods, upper and lower shaft clamps, U-bolts, leaf springs, and parallel arms. The leaf spring is fastened to the axle body of the axle with U-shaped bolts, and both ends are clamped in the frame bracket, which are connected in series by the balance arm, and the balance arm is balanced within a certain range. The leaf spring mainly receives the vertical gravity on the frame, and the horizontal force is transmitted by the lower axle card and the tie rod. By adjusting the tie rods, the shaft can be adjusted in parallel to avoid abnormal tire wear.
Axle-tires assembly: Consists of tires, rims, wheels, brakes and axles.
Brake and electric system: brake system is used for normal driving braking and emergency driving braking. Brake system is composed of air joint, inflation line, control line, emergency relay valve, gas cylinder, brake air chamber. The electric system plays the role of lighting and transmitting signals. It is connected to the tractor by a seven-star plug, and the wiring is generally hidden in the frame.
Side guard: Protect and block outside objects entering the lower part of the trailers.
Tool box: Used to keep tools and other cargo like tarpaulin and rope, normally be put on the side or behind of trailer.