The Fifth-wheel coupling is not just a piece of iron

Semi-trailer tractor has become one of the main means of transportation in the transportation industry due to its advantages of large transportation volume, convenient loading and unloading, and low transportation cost.

The fifth-wheel coupling is the key component connecting the tractor and the semi-trailer. It plays an important role in transmitting the longitudinal braking force between the fifth-wheel coupling of the semi-trailer and the trailer. The structure of the shock under various motion forms such as braking directly affects the operational safety of the entire system.

Composition of fifth-wheel coupling

1. Saddle body, the main component of fifth-wheel coupling.

It is composed of shell (also called seat cover), front frame plate, rear frame plate, M-frame plate, frame inner gasket, frame outer gasket, U-shaped plate, tail slide cover plate.

2. Bracket for fixing fifth-wheel coupling.

The two brackets are connected with the vehicle frame through the fifth-wheel coupling bottom plate, so as to fix the fifth-wheel coupling and play a supporting role.

3. The pull rod is used to control the relative movement of the lock hook and the inclined iron.

The pull rod realizes the separation of the lock hook and the fifth-wheel coupling by driving the inclined iron to move laterally. When the semi-trailer is in normal operation, the tie rod is fixed by the locking boss, thereby realizing the locking of the lock hook and the fifth-wheel coupling, and ensuring the connection between the tractor and the semi-trailer.

4. The inclined iron is used to control the separation and locking of the lock hook.

The inclined iron is driven by the pull rod to move laterally and assist the lock hook to rotate at a certain angle to realize the locking and separation of the traction pin.

5. The lock hook is used to control the locking and separation of the traction pin.

When the inclined iron is moved to the proper position, the U-shaped lock hook will be pulled by the spring and then rotated around the pin seat by a certain angle to realize the locking and separation of the traction pin, and at the same time realize the connection and separation of the two vehicles.

Working principle of fifth-wheel coupling

Manually pull the lever to the outside to drive the lock hook to rotate around the pin seat, and at the same time, the opening of the lock hook turns to the outside to realize the decoupling of the traction pin and complete the separation of the two vehicles.

Repeat the above steps to turn the opening of the lock hook to the outside. When the tractor makes the opening of the lock hook face the traction pin, move backward until a collision occurs, and the lock hook rotates to the starting position under the action of the spring rebound. When the lever is released, the inclined iron will automatically return to the original position, and the safety pin will also return to the original position at the same time, realizing the self-locking of the lock hook and the smooth connection.

Classification of fifth-wheel coupling

According to the size of the traction pin, it is divided into 50 and 90. Trailers used for ordinary road transportation are usually equipped with 50fifth-wheel coupling, and 90fifth-wheel coupling is widely used in construction machinery transportation trailers and heavy-duty trailers.

Maintenance of fifth-wheel coupling

The service life of the fifth-wheel coupling depends on whether it is lubricated for the first time. Please use qualified heavy-duty grease, it is recommended to use heavy-duty grease containing graphite or molybdenum disulfide. Its good extreme pressure and anti-wear properties will ensure that the fifth-wheel coupling surface will not produce abnormal wear under normal working conditions.