Suspension, also known as suspension, is the general name of all force transmission connecting devices between the semi-trailer frame and the axle. It is used to transmit the force and torque acting between the wheel and the frame, buffer the impact force transmitted from the road to the frame or body, and reduce the vibration caused thereby, so as to ensure that the vehicle can run smoothly.
In general, the suspension of semi-trailer can be divided into four types:
1. Rigid suspension.
The body chassis of rigid suspension directly acts on the axle between the wheels without spring as buffer. In case of uneven road surface, it completely depends on the swing of balance beam to maintain the relative balance of front and rear axles.
This kind of suspension is relatively rare at present, because its damping effect is very poor. It is mainly used in low-speed flat semi-trailer carrying goods.
2. Leaf spring suspension
Also known as series leaf spring balanced suspension, that is, the common leaf spring suspension, which is mainly composed of leaf spring, suspension support, connecting rod, U-bolt, etc.
The biggest advantage of this trailer suspension is low cost, reliable operation and convenient maintenance. Because of this, steel plate suspension is currently the largest application proportion in domestic semi-trailer, about 70-80%.
3. Bogie suspension.
That is, the common front and rear supports of leaf springs are reduced to a single support connected to the vehicle body, which can divide the force points equally to different axles, so the bearing capacity is larger, which is generally used on heavy trailers.
4. Air suspension.
Also known as airbag suspension, its most remarkable feature is the airbag air spring. Compared with other suspensions, the cushioning force of air suspension is better, which can effectively protect goods and improve driving comfort. At present, it is mainly used in the transportation of precision instruments and dangerous chemicals.
Advantages of air suspension:
1. Good shock absorption effect. Compared with the traditional leaf spring, the air bag is obviously softer and more comfortable. It forms a soft connection between the frame and the axle. The bumps and impacts from the road can be alleviated to a great extent. In addition to enhancing driving comfort, it is also a kind of protection for goods.
2. Reduce load stress. The compressibility of the air makes the air bag suspension easy to deal with the bumps of the road, reduce the load stress, prolong the service life of the axle and semi-trailer, and reduce the vehicle cost to a certain extent.
3. Its own weight is smaller. Lightweight is a development trend of the trailer accessories industry at present. Compared with the traditional suspension, the air suspension has lighter weight and can obtain more spare weight space for standard load users, while no-load users can save fuel, save energy and increase efficiency.
4. Long service life. The friction of the air spring is 2-3 times lighter, and the service life of the air spring is better.
Air suspension has many advantages, but there are also some disadvantages objectively:
1. Compared with other suspensions, the structure of air suspension is more complex, because to adopt air spring, it is necessary to set up a bar system that can transmit various forces and moments other than vertical force, which also leads to its high price to a certain extent.
2. Corresponding to the high price is the maintenance cost. In addition, compared with the traditional leaf spring, the airbag is easier to be damaged in material, and the maintenance cost can not be underestimated.
3. Once the air suspension fails, it cannot continue driving. Unlike the traditional suspension, even if there is an oil leak, you can stick to the maintenance point.
4. The air suspension has good cushioning, but under the condition of full load, nodding or trailing will occur when braking or starting, and skilled driving skills are also required.
