Basic Knowledge of Semi-Trailers
1. Semi-Trailers and Their Classification
Concept of Semi-Trailer and Semi-Trailer Train:
(1) Semi-Trailer: A trailer towed by a semi-trailer with some of its mass borne by its tractor.
(2) Semi-Trailer Train: A semi-trailer and its semi-trailer tractor together are called a semi-trailer train. According to GB1589, except for low plate and container skeleton cars longer than 12.2 meters, the length of the train shall not exceed 16.5 meters.
Semi-Trailer Classification:
According to Length: 8.6m, 10m, 11.16m, 12.1m, 12.5m, 13m
By Tonnage: 9T, 15T, 20T, 22T, 25T, 26T, 28T, 30T, 31T, 32T
By Model: Common railings, warehouse railings, coal pulling semi-trailers, self-discharging semi-trailers, low flat semi-trailers, container flat semi-trailers, container frame transport semi-trailers, van semi-trailers, etc.
According to the Number of Axes: 1 axle, 2 axles, 3 axles
GB1589 Length, Width, and Height Limits:
Length:
1 axle: up to 8.6m
2 axles: up to 10m
3 axles: up to 13m
Low plate semi-trailer and vehicle transport semi-trailer, and those longer than 12.2m (40 ft) are exceptions.
Width:
Ordinary: not more than 2.5m
Low plate, hot metal transport semi-trailer: not more than 3m
Van type: not more than 2.55m
Height: No more than 4m
2. Main Structure of the Semi-Trailer
Carriage, Frame, Leg (Support Device), Suspension, Axle (Axle Assembly), Electrical Road, Protective Net, Toolbox, etc.Carriage Door Number and Height:
Commonly used: 11 doors, 600mm high
Carriage Form: Large vertical, small vertical, flat, waveform, embossment
Hinge Form: Large hinge, small hinge, flat hinge, cast steel hinge
Thickness: Standard 1.5mm, light truck 1.2mm, heavy coal pulling and self-discharging semi-trailers 2.0mm
Border: Square tube. Small vertical: 70502 square tubes, Large vertical: 100502 square tubes
3. Semi-Trailer Types:
X-Type Box: Corrugated box, vertical box, X-type box, flat box
Hinges: Large hinge for coal pulling truck, cast steel hinge plate
Dump Semi-Trailers:
Low chamber without automatic door opening mechanism, typically used for steel transport, height of chamber: 600mm.
High chamber with automatic door opening mechanism, large vertical slot, plate thickness: 2mm, box frame: 100503 square pipe welding.
Doors with a single width greater than 1800mm and height greater than 2000mm have three lock bars, others have two lock bars.
4. Frame:
Composition: Girder camber, automatic tracking submerged arc welding machine (imported from the United States)
Standard Structure:Gooseneck structure frame (girder)
Upper and lower wing thickness: 12/14/16/18/20
Web thickness: 6/8/10
Material: Q235, 16Mn
Height: 450/480/500/520/550
Frame (through beam): Square tube or channel steel, economic type is 3mm plate fold.
Frame (side beam): 14#, 16#, 18#, 20# channel steel
Frame (bottom plate): 3mm pattern plate, 4mm plate material Q235
Frame (bottom plate cushion iron): 1007030*3 brim
5. Leg (Support Device):
Function: Supports the load at the front of the semi-trailer after hanging.
Structure: Consists of base, pull rod transmission mechanism, inner tube, outer tube, gearbox, control crank, etc.
Classification: Single action, linkage (each single action leg has a crank, linkage only one on the right), 8T, 28T
6. Suspension:
Working Principle: Leaf spring is fastened with U-bolts on the axle body, ends are supported by the frame, connected in series through the balance arm, which balances within a certain range. The leaf spring primarily absorbs vertical gravity on the frame, and horizontal force is transmitted by the lower shaft clamp and pull rod. Adjusting the pull rod ensures parallel alignment of the shaft to prevent abnormal tire wear.
Function: Transfers load and absorbs shocks.
Structure: Includes branches, frame, tie rod, upper and lower shaft card, U-bolt, leaf spring, parallel arm, etc.
7. Axle Assembly:
Structure: Composed of tires, steel rings, wheels, brakes, and axles.
Tire Rim Matching:
12.00-R20 Explanation: 12.00 refers to the wide section of the tire, R means steel tire, 20 rim diameter.
10.00-20, 11.00-20, 12.00-20 steel rings.
Circuit: Used for lighting and signaling.
Air Path: For normal and emergency braking, composed of gas joint, inflation pipeline, control pipeline, emergency relay valve, air storage cylinder, and brake air chamber.
8. Protective Guardrail:
Rear Guard Fence Forms: Type A, Type B, Type C
Type A: Ordinary railboard, warehouse semi-trailer
Type B: Low plate, self-discharge semi-trailer, van pulling coal
Type C: Container transport semi-trailer
9. Toolbox:
Sizes: 1000mm, 1.4m, 2.5m for various types of semi-trailers including rail plate semi-trailers, van semi-trailers, coal pulling semi-trailers, and container plate semi-trailers.
10. Concepts of Semi-Trailers:
Front Suspension: Linear distance between the traction pin axis and the front end of the semi-trailer (including the border and gas path joint).
Rear Suspension: Linear distance between the center of the final axle and the end (including the rear handle and protrusions).
Wheelbase: Distance between the traction pin axis and the first axis.
Wheel Pitch: Distance between the center lines of tires on both ends of the same axle.
Height: Height of the frame from the ground.
Front Turning Radius: Distance between the pin center and the furthest point of the front end.
11. Warehouse Fence Structure:
Opening Mode: Warehouse fence is divided into two layers, with varying heights and door openings. The height of the warehouse grid is 1200mm, divided into two layers (400mm upper, 800mm lower). The warehouse grid can be removed and must be specified in the contract if wire drawing is required.
12. Gantry Frame Type Front Compartment:
Composition: 4 reinforcing columns, iron seal to the top. Double handlebars in the side compartment, the column is not removable.
13. Miscellaneous:
Removable Components: Various sections of the grid and bin with specified dimensions and removable components. The front box with curved plate and cross-braced stays.
