Views: 0 Author: Wondee Autoparts Publish Time: 2022-12-08 Origin: Wondee Autoparts
Design Specifications for Semi Trailers (Part 2)
----Calculation specifications and technical requirements of common parts
1.1. Suspension system
Semi trailer suspension systems mainly include American mechanical suspension, German mechanical suspension, Air suspension and Bogie suspension.
1.1.1 American mechanical suspension
The height H adopted by American mechanical suspension includes 130mm, 150mm, 180mm, 200mm, 225mm, etc. As shown in Figure 1 below.
Figure 1. Schematic diagram of American mechanical suspension
According to different vehicle design requirements, the common American mechanical suspension configurations are shown in Table 1 below:
φ50 | δ5 | Standard 40t |
φ60 | δ6 | 40t-60t |
φ60 | δ8 | 60t-80t |
φ70 | δ8 | 80t-100t |
Remarks: Light duty parts or heavy duty parts can be selected for the parts other than hangers according to the carrying tonnage. |
Table 1. American mechanical suspension configuration
1.1.2 German mechanical suspension
The height H of German mechanical suspension is usually 155mm, as shown in Figure 2 below:
Figure 2. Schematic diagram of German mechanical suspension
According to different semi trailer design requirements, the common American mechanical suspension configurations are shown in Table 1 below:
Table 2. German mechanical suspension configuration
1.1.3 Air suspension
The height FH of air suspension is usually designed according to customer requirements, and the range is generally 340-470mm. The overall load capacity design of air suspension is 9-13 tons, as shown in Figure 3 below.
Table 3. Schematic diagram of air suspension
1.1.4 Bogie suspension
The bogie suspension is mainly used in the African market , Middle-east market and some Southeast Asian markets. Its loading capacity mainly includes 24 tons, 28 tons and 32 tons. As shown in Figure 4 below.
Table 4. Schematic diagram of bogie suspension
The common bogie suspension configurations are shown in Table 3 below:
Axle tonnage configuration | Thickness of support plate | Suitable vehicle tonnage [T] |
12T | δ12 | 40T |
14T | δ14 | 40T-50T |
16T | δ16 | 50T-60T |
|
Table 3. Bogie suspension configuration
1.2. Specifications of common tires and rims
According to the standard GB/T2700-2016 (Tyres’ specification, size, pressure and load of heavy duty vehicles), in the design of semi-trailers, the configuration of tyres and rims usually refers to the data in the following table, as shown in Table 4 below.
Tyre specifications | 11.00R20 | 11R22.5 | 12.00R20 | 12R22.5 | 315/80R22.5 | 825R20 |
540 | 520 | 560 | 540 | 540 | 480 | |
8.0-20 | 8.25*22.5 | 8.5-20 | 9.0*22.5 | 9.0*22.5 | 7.0-20 | |
3075kg | 2825kg | 3450kg | 3075kg | 3450kg | 2120kg |
Table 4. Common tire and rim parameters
1.3 Leaf springs
A Leaf spring is an important part in mechanical suspension system. American and German mechanical suspension usually includes the following specifications of leaf springs, as shown in Table 5 below.
Specifications | Width(mm) | Thickness(mm) | No. Of leaf | ||
90x13x10L | 90 | 13 | 10 | 6800 | 280 |
90x16x9L | 90 | 16 | 9 | 7500 | 300 |
90x16x8L | 90 | 16 | 8 | 6800 | 285 |
90x16x7L | 90 | 16 | 7 | 6000 | 260 |
100x12x12L | 100 | 12 | 12 | 8200 | 300 |
100x12x14L | 100 | 12 | 12 | 9200 | 325 |
100x14x12L | 100 | 14 | 14 | 9500 | 325 |
Table 5. Design Parameters of Leaf Spring
2. Design and calculation specifications of semi trailers
The height dimensions commonly used in semi-trailer design are shown in Figure 4 below.
Figure 4. Semi trailer height diagram
The dimensions are explained as follows:
1) H1: traction height, the height from the top surface of the fifth wheel of the tractor to the ground.
2) H2: Height of the front longitudinal beam
3) H3: Height of the rear longitudinal beam
4) H4: Suspension height
5) H5: Calculation height of the leaf spring
6) H6: Radius of tire.
7) H: Height of the rear cargo platform of the semi-trailer.
8) h: Height difference between heights of the front and the rear of the semi-trailer.
2.1 Height calculation of suspension
H4=H1+H2-h-H3-H5-H6
2.2 Height calculation of the rear cargo platform
H=H3+H4+H5+H6
The height design of semi-trailer is a comprehensive problem, which requires comprehensive consideration of vehicle use requirements and the parameter performance of each part to make a proper choice.
2.3 General technical requirements for semi trailers
The general technical requirements for semi-trailer design are shown in Table 6 below.
By WONDEE Autoparts
2022-12-8