Dump semi-trailer refers to a kind of semi-trailer that can automatically tip over the carriage angle during unloading and quickly complete the unloading task. Its unloading efficiency is high, which can greatly save unloading time and labor, shorten transportation cycle and improve production efficiency. Generally, dump semi-trailer is widely used in the transportation of loose goods such as sand, soil and coal.

Many semi trailers do not have the self unloading function when they leave the factory, but it is found that this function is needed in practical application. Can they be designed and installed by themselves? In fact, it is OK, but it needs to be filed in advance and marked on the certificate and driving license, otherwise it may affect the annual review and even be regarded as illegal modification.

The installation of dump function can be understood as adding a lifting mode to the carriage. At present, the hydraulic power system is more popular in the market. Although there are many versions of dump truck, the lifting mode is basically not much different. So the question comes: which kind of hydraulic top is more reliable and stable?

The hydraulic jack of dump truck can be divided into the following four types:

1. Front hydraulic jack.

The front hydraulic top is called "front top" for short. As the name suggests, the hydraulic top is installed in the front of the cargo compartment. It usually appears on medium and large dump trucks, and is relatively less used in vehicles with small wheelbase.

According to the lever principle, the top stroke of the front roof is relatively long, that is, the torque is long, so the lifting force is relatively stronger, which is more suitable for lifting heavy objects, such as muck and coal, which is one of the reasons why it appears more on medium and large dump trucks.

In addition to the large lifting force, the front roof also has the characteristics of fast lifting speed, simple structure and easy maintenance.

It should be noted that this lifting method also has some disadvantages. Since the front roof is installed between the cab and the cargo compartment, it will occupy the length of the vehicle body and shorten the size of the cargo compartment to a certain extent. In addition, although the front jack has advantages in lifting force and lifting speed, when loading and unloading goods with uneven weight distribution, it is prone to bias, resulting in bending of the jack rod, affecting telescopic lifting, and even the risk of breakage of the jack rod, which must be paid great attention to.

2. Central double top.

The middle double roof is installed in the middle under the cargo compartment and is composed of two hydraulic roofs. Compared with the front roof, the middle roof can reduce the center of gravity of the vehicle and has better stability during lifting. It is more suitable for short single axle dump trucks.

In the case of uneven distribution of cargo weight mentioned above, it is more appropriate to use the middle double roof. Compared with single roof, double roof is more suitable for complex working conditions, such as sandy road or other uneven roads, and its adaptability is better.

In addition, in the installation position, the middle double roof does not affect the length of the cargo compartment, but relatively occupies more girder space. During the operation, the two hydraulic jacks shall be lifted synchronously. If any one of them fails, it will affect the other hydraulic jack, ranging from the bending of the ejector rod to the overturning of the vehicle.

3. Central horizontal roof.

The reason why it is called "horizontal roof" is that this hydraulic roof lies inside the vehicle girder in the retracted state. Compared with the first two kinds of hydraulic roof, the structure of the middle horizontal roof is more complex, which is composed of multiple groups of pin shafts. On the contrary, its performance is generally better than the first two, and its stability and bearing capacity are relatively balanced. It can be said that it has both the lifting force of the front roof and the stability of the middle double roof, and the middle horizontal roof is also installed under the cargo compartment without occupying the length of the compartment.

However, the central horizontal roof is not without disadvantages. Corresponding to its complex structure, it is the increase of failure rate. After all, there are many parts, and any failure will affect the overall use, such as loosening or fracture of the connection under long-term lifting. The maintenance convenience is not as good as the first two lifting methods.

4. Rollover hydraulic roof.

The front three lifting methods belong to the backward tipping hydraulic roof. Because in the conventional backward tipping dump, the height of the ejector rod is affected by the length of the carriage, and the longer the length of the ejector rod required by the vehicles with longer cargo compartment, but the gradual climbing design adopted by the ejector rod is thinner to the tail, which is unfavorable to the lateral stability of lifting. Therefore, in order to meet the operation requirements, the rollover lifting structure has been produced.

The rollover hydraulic jack does not have too many requirements for the length of the ejector rod. It is not even half as high as the middle double roof. It is arranged in a row at the bottom of the cargo compartment. Although the appearance looks relatively small, the lifting force is recognized, and the rigidity of the cargo box is more guaranteed. If the mobile outrigger is used at the rear of the vehicle, the tire burying of goods can be avoided during unloading.

However, the rollover lifting also has disadvantages, such as higher requirements for the unloading site and uneven stress on the girder during unloading. Generally, the rollover hydraulic roof is more applied to trailers with a cargo compartment length of more than 9.6m.

Generally, the dump truck and semi-trailer transport heavy goods, so the requirements for the vehicle chassis should be higher, especially the axle assembly, which must be 100% reliable. Darong heavy industry group is the first axle enterprise to mass produce one-piece axles in Liangshan, Shandong Province. It has accumulated 20 years of experience so far. The group has built a 32000 ㎡ standard chemical plant. More than a dozen production processes from blanking to assembly are strictly controlled by unified standards. The axle has excellent strength, toughness, ductility and fatigue resistance, especially better than the traditional three-piece axle in heavy load performance and stability, so as to provide higher safety guarantee for vehicle owners and improve vehicle operation efficiency.