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Introduction of Low Bed Trailer

Low bed lowboy trailer.jpg

I. What is a low flatbed semi-trailer?

Let's make a detailed introduction. First of all, low flatbed semi-trailers are usually used to carry heavy things, such as tractors, buses, special purpose vehicles, etc., as well as rail vehicles, mining machinery, forestry machinery, agricultural machinery (excavators, loaders, pavers, cranes, etc.).

Compared with container semi-trailers(SUNSKY TRAILER usually transport containers by sekletal semitrailers), it has a lower center of gravity, better stability and safety, so it has a better ability to pass overhead barriers when transporting high goods.

When loading machinery into a low bed semi-trailer, we usually load the machinery from the rear end of the low bed semi-trailer, that is, we usually move the machinery from the rear wheel frame or remove the wheels, and then fix the machinery to the low bed trailers.

low bed trailer transport excavator

low bed trailer transport excavator

II. Structure of Low Bed Semitrailer

Generally, low bed semi trailers use concave beam - type frames. Namely, the front part of the frame is the gooseneck (note: the front end of the gooseneck is connected with the traction saddle on the traction, and the back end of the gooseneck is connected with the semi-trailer). General in the middle for the cargo platform (is the lowest part of the frame that we know), the rear section for the wheel frame (including wheels).

III. Body assembly for low bed semitrailers

1. First of all, let's see the jack of low bed semi trailer.

Jack is not unfamiliar to the owners of low bed semi-trailers and fence semi-trailers, but it is necessary to pay more attention to some matters in the process of use, in order to prevent the occurrence of accidents.

(1)The support bar on the jack arm should be inserted into the groove of the fixed support point to fix the jack.

(2) the kilo should be top in the specified support position, otherwise it may cause damage to low bed semi-trailer, van semi-trailer and other vehicles or the occurrence of accidents.

(3) the jack foot must be supported on the hard road surface, if the ground is soft, you can find some wood blocks to bear the weight, not directly supported on the soft ground.

(4) when lifting the jack must be slow, not directly removed, pay attention to the balance of the vehicle.

2 axles low bed semitrailer

2 axles low bed semitrailer

2. Next is the transmission shaft of the low bed semi-trailer.

The transmission shaft is responsible for the transmission of power to the wheel device, the main role of the drive shaft is in the process of driving to prevent damage to low bed trailer. Due to the transmission shaft is using a patterned constant speed universal joint, and the joint part is sealed with rubber sleeve, if rubber casing damage, low bed semi-trailer, skeleton transport container semi-trailer is running, the debris will enter the joint of the universal joint, cause the wear of the drive shaft, and then affect the service life of the drive shaft.

3. The third is the maintenance of the low bed semi-trailer.

Maintenance for any vehicle will not be unfamiliar, without maintenance, the service life of the vehicle will be greatly discounted.

4. Finally, the seat belt of the low bed semi trailer.

Seat belt is the most familiar to the owners of low bed semi-trailers and other vehicles,what need to tell you is that the vehicle must fasten the seat belt, because the seat belt is sometimes directly related to our life safety, which is also a point in the vehicle safety driving experience.

which is not unfamiliar to the owners of low bed semi-trailers and other vehicles. We hope that everyone will pay full attention to it and pay more attention to some safety precautions.

3 axles low bed trailer

3 axles low bed trailer

IV. Low bed semitrailer features

Low bed semi trailer is also very widely used, suitable for a variety of machinery and equipment, large objects, highway construction equipment, large tanks, power plant equipment and various steel transport.

The low flat

low flat

1. Series low bed semi trailer has flat plate type, concave beam type and tire exposed type structure, longitudinal beam adopts straight type or gooseneck type. Its frame is ladder type, longitudinal beam section for I-shaped, with high stiffness, high strength characteristics.

Frame loading

Frame loading

2. The main plane of the frame cargo platform is low, to ensure the stability of transportation, suitable for carrying all kinds of construction machinery, large equipment and steel, etc.

Three-axis balanced

Three-axis balanced

3. Using three-axis balance type, biaxial balance type or rigid suspension, between the front and rear plate,spring is equipped with a mass balance block, can make the front and rear plate spring deflection of the same amount of change, so that the front and rear shaft stress equilibrium.

4. Low bed semi trailer series products are suitable for a variety of machinery and equipment, large objects, highway construction equipment, large tanks, power plant equipment and various steel transportation, widely used, efficient and fast. The vehicle adopts advanced computer-aided design software, which is flexible and diverse for optimization design.Design the load surface of the frame according to the requirements of the users, to meet the transportation of various special goods. Low bed semi trailer is used for pulling mechanical equipment, large equipment such as excavator, bulldozer, etc. It can be equipped with 30 tons, 50 tons, 60 tons, 80 tons, 100 tons, 120 tons, 300 tons of low for two and three axles. The flat plate can be pumped and pulled, and hydraulic ladder can be installed.

V. Specification of low bed semi trailers

The two axles:9m, 11m, 12m and 13m.

General configuration size: L × W (11x3m)

Heavy configuration: longitudinal girder height 500mm, upper wing 20mm, lower wing 20mm, web 12mm, side beam 25# channel steel, commonly known as 14# channel steel, bottom plate 4mm pattern, Fuwa shaft 13 tons * 2, 8 standard steel rings, spare tire frame 2, 28 tons of legs.

Tyres: 8.25-20 wire x8.13m.

11.2 meters 2 axle low bed trailer drawing

11.2 meters 2 axle low bed trailer drawing

Three axles: 9.5m, 11m, 13m and 13.75m.

Low bed semi-trailer low price offer, the configuration of conventional configuration size length * width (13 x3m).

Heavy configuration: longitudinal beam height of 500 mm, 20 mm on the wing, wing plate under 20 mm, 12 mm, web side beam 25 # channel steel, known as 14 # channel steel, floor 4 mm pattern, Fuwa 13 tons of x 3 root bridge standard rims x 12, spare tire rack 2, 28 tons of leg.

Tyre: 8.25-20 steel wire tire x12.

13 meters 3 axles Concave beam low bed trailer drawing

13 meters 3 axles Concave beam low bed trailer drawing

VI. SUNSKY produce professional low flatbed trailers

SUNSKY TRAILER produce 13 meters low bed semi-trailer, 12 meters low bed trailer, 10 meters low bed semi trailer, lightweight hollow beam hook machine low bed trailer, tires appear type low bed semi-trailer, trailer plate, 13 meters high and low level low bed semi-trailer, tri-axle low bed semi-trailer, mechanical transport semi-trailer, plate type excavator truck. Offer low bed semi trailer for reasonable price.

Carbon dioxide gas inverter welding.The whole frame is shot peening to make the trailer more beautiful. The whole truck adopts advanced computer-aided design software to optimize the design, according to the trailer load quality requirements, the finite element analysis of the frame, scientific design, reasonable load.

Due to the low platform of the ground semi-trailer, the upper part provides large loading space, and the low center of gravity after loading makes the trailer run safely and reliably. Various models, flexible design, according to user needs to design the bearing surface of the frame, to meet the transport of various special goods. It has been exported to many countries and regions.

13 meters 3 axles low bed trailer drawing

13 meters 3 axles low bed trailer drawing

Excellent technology. The main parts of the trailer are processed by advanced equipment, and the longitudinal beam is welded by automatic submerged arc welding machine; The wheel and axle assembly is realized by the assembler, and the wheelbase is guaranteed by the distance finder. The electric circuit of the whole trailer is debugged by using the electric test bench. The parts of the trailer are treated with shot peening, which greatly enhances the adhesion of the paint.

Frame. The frame is composed of welded steel longitudinal beam and reinforced beam, which takes into account the strength, stiffness and toughness of the frame in a balanced way, and has strong bearing capacity and no permanent deformation.

Axles. Axles are of high quality produced by professional trailer manufacturers, with strong load-bearing and easy deformation. At the same time, domestic ABS anti-lock braking system can be choose to reduce the braking distance and effectively prevent the occurrence of vehicle side slip and tail swing caused by wheel lock during emergency braking, thus improving truck driving safety.

14 meters 4 axle low bed trailer drawing

14 meters 4 axle low bed trailer drawing

VII. Suspension System of Low Bed Semitrailer

1. Rigid suspension


 axle with spring rigid suspension

Automobile suspension system refers to the spring and shock absorber between the body and the tire composed of the whole support system. Suspension system should have the function to support the body, improve the feeling of riding, different suspension settings will make the driver have different driving feelings. The seemingly simple suspension system, which combines multiple forces, determines the stability, comfort and safety of a trailer, and is one of the key components of a modern vehicle.

Rigid suspension is a suspension method of clamping the contact wire on the low bed semitrailers' bar. By the rigidity of the trailer bar itself, the contact wire is kept at the same installation height, so that the contact suspension system has the minimum structure height by eliminating the chain suspension bearing cable and making the maximum use of the limited suspension space. The contact wire and trailer bar in the rigid suspension system are not affected by the tension. Compared with the flexible contact suspension system, there is no possibility of breaking the wire.


spring leaf

As a new type of contact suspension, rigid suspension catenary has the characteristics of less space, simple installation, less maintenance, good stability, safety and reliability. Rigid suspension system is characterized by high resistance, only a few parts are mobile, and the distance of movement is small.The contact wire is strengthened along the full length of the bus bar and does not bear mechanical stress, so the wear is minimal during the operation and no maintenance and adjustment is required.

The most commonly used rigid suspension is the axis hanging, with two lines of four axles, three lines of six axles, etc., which is mainly suitable for low-speed cargo carrying axis low bed semi-trailer, concave beam type trailer. Its damping effect is poor at high speed.

one line two axles low bed trailer drawing one line two axles low bed trailer

one line two axles low bed trailer

2. How to separate rigid suspension and flexible suspension?

(1) Different properties

The left and right wheels of the rigid suspension are connected by an axle, and the weight wheel is directly fixed on the low bed trailer body without using a spring.

The left and right wheels of the flexible suspension are not connected to the wheels.

(2) Different usage

The use of rigid suspension is from the point of view of protecting the vehicle parts and the driver's comfort. The speed of low bed semi-trailer with rigid suspension should not exceed 3 ~ 4 km/h, which is slower than the normal walking speed of people.Fuel tank trailers and LPG tanker trailers and other vehicles use flexible suspension.

two line four axles low bed trailer drawing two line four axles low bed trailer

two line four axles low bed trailer

VIII.How to keep cargo stable on a low bed trailer

1. Increase the scale of base

You can increase the size without automatically increasing the stability by increasing the size of the support. Increase your strength in the direction of obstruction.

One way to increase the size of a base is to increase the base support by changing the location so that the widest part of the object is on the ground. Another approach is to increase the number of contact points with the ground where possible.

For some larger objects, you may need to create more touch points by changing the packaging or changing the location. In addition, low bed trucks used to transport machinery can be widened with the necessary accessories to increase the size of the working platform.

2. Increase friction

The stability of an object is affected by the level of frictional resistance between one or more contact points and the foundation or ground. When the frictional resistance is low, the object will slide or even slip on the ground. So, increased friction equals improved stability, especially on smooth surfaces. Select a surface with rough packaging when considering the surface of the contact point.

Sometimes shippers may use wood chips on the sold low bed truck trailers to keep the weight with smooth surface stable. You can add any other rough material to the floor or base to increase friction, as long as it does not damage the object.

3. Lower center of gravity

The position of the center of gravity of the supporting base determines the stability of the object. If the position is above the base, the higher the pile, the less stable the object will be. This explains why objects piled high tend to tip over.

The way to increase stability is to lower the center of gravity or reduce the distance between the center of gravity and the ground. Therefore, a double deck towing plate is a good choice to lower the center of gravity.

When carrying high objects, the object should be dumped before being carried, rather than carried upright. When you tilt a tall object or any other object, you may automatically lower the center of gravity.

detachable semi-trailer drawing detachable semi-trailer

detachable semi-trailer

4. Slow down

High speed increase the chance that it will roll over. But speed does not affect the center of gravity of an object, but determines how much force an object reacts to an external force. For example, if you are transporting an object at high speed with a 4-axis heavy-duty low-frame trailer, suddenly stopping or hitting an obstacle will cause the object to tip over. At high speeds, sometimes applying the brakes can cause objects to fall or slide. Walking at a low speed helps to keep the center of gravity or balance in the same position if you are carrying something.

5. Driving skills

Drivers drive steadily, which can be improved through training. Place the object at the center of the supporting base. The vertical projection of the center of gravity should be at the center of the supporting base. In other words, the equilibrium point should be at the bottom of the object's stability or at the center of the ground.

When a low bed semi trailer or transporter changes its momentum, anything placed on the edge of the trailer is likely to fall. By placing an object in the center, you stabilize the center of gravity and prevent the object from falling.

IX. Driving skills of low flatbed semi-trailers

What is it about the slanting direction of the low bed semi trailer?Low bed semi trailer is a kind of commonly used semi trailer, but the driving of low bed semi trailer still need to pay attention to a lot of problems, the following is to talk about how low bed semi trailer slanting direction happened.

1. The vehicle deviation is mainly because the distance between the traction pin center and the corresponding points on both sides of the axle is different (three points are not isosceles triangle). If the deviation is out of alignment, it may cause abnormal tire wear (serrated phenomenon).

2. Detection and adjustment method:

(1) Park the low bed trailer on the level road without braking.

(2) Take a point on the inner surface of the front wheel hub of the front axle, and take a point on both sides of the left and right, and the position is symmetrical.

(3) Take the traction pin center as the reference, measure the distance to the above two points, the requirement is "L1-L2 3mm. If the deviation is out of line, adjust the front axle live tie rod until it meets the deviation requirements.

(4) Before measurement, check the measured value at the corresponding point of the rear axle hub, and 2m is required. If out of tolerance, adjust the rear axle live tie rod, make the front and rear axis parallel, until the deviation meets the requirements.

(5) Tighten the fastening bolts on the front and rear pull rods.

(6) After the adjustment, drive low bed trailer about one kilometer, stop at the same place without braking, and check the above size. If there is no change, the adjustment is successful.

(7) The adjustment process should make the tie rod in working state, that is, once the tie rod is rotated, the vehicle bearing moves, the adjustment of the tie rod is normal.

X. If you're a beginner,how to drive a semitrailer?

A semi-trailer is a trailer with an axle placed behind the center of gravity of the vehicle (when the vehicle is uniformly loaded) and equipped with a coupling device that transmits both horizontal and vertical forces to the tractor. Semi-trailer is generally a three-axle semi-trailer, which is divided into fence semi-trailer, skeleton container semitrailer, low bed semi-trailer,tank semitrailer and many other kinds. It is a heavy transport vehicle connected by a traction pin and a semi locomotive. So how do beginners drive semitrailers?

1. Start skills

Semitrailer at the start of driving must use a first gear, loose lift clutch pedal to be stable but not fierce, to avoid the use of semi-clutch, to prevent burning out the clutch friction plate.

2. Watch the gas pedal

To properly increase the throttle, the wheel difference is larger, such as the outside of the semitrailer front position has a deviation from the distance,you should try to take a big turn.

3. The brake

Semi-trailers are generally all-wheel braking, so the braking performance is better, can be appropriate to use the brake.


braking system

4. Semitrailer backing up

When reversing, the turning direction of the steering wheel shall be the reverse direction, tractor and trailer start backing in a straight line, to make the rear of the swing to the left (right), turning the steering wheel to the right (left), when found the rear of the swing in the direction of the target,you should immediately appropriate rotary steering wheel, if move to the rear of the pendulum is insufficient, you can still (right) turn the steering wheel to the right, if the rear of the pendulum is moving too much, you should turn to the left (right) a little more.

5. Turn around

When the semi-trailer turns around, it should generally choose a wider intersection, so that it can be completed once in advance and in reverse.

6. Separation

When need to separate the tractor and trailer, first, the semi-trailer tire is blocked with triangular wood or stone before and after, so that it does not slip, then the auxiliary support frame of the semi-trailer is lowered to contact the ground, and the joint of the brake pipeline and the plug of the cable for the light are untied.Then open the locking mechanism of the saddle grinding plate to make the tractor drive away from the semi trailer and complete the separation.

7. Combination with a tractor

To make the tractor and semi trailer recombination, operate equidistant in the opposite direction.

XI. Transmission and clutch failure troubleshooting for low bed semitrailers

This is one of the most common failures of manual transmission. Low Plate Manual Transmission Misalignment refers to the phenomenon that when the clutch is in normal technical condition.The transmission in two gears at the same time, or in the wrong gear. There are very few reasons for this kind of failure, so correspondingly, its elimination methods and solutions are much less.

low bed trailer landing gear

low bed trailer landing gear

First, the interlocking device failure: such as fork shaft, interlocking pin or interlocking steel ball wear too much.

Second, The lower arc working face of the gear lever is worn too much or the groove of the dial block on the fork shaft is too large.

Third, the transmission lever ball head positioning pin is broken or the ball hole, the ball head wear is too loose will also cause the phenomenon of low flat manual transmission jump gear. In a word, the main reason for the chaos is caused by the failure of the transmission control mechanism.

With the above three points of analysis, we will carry out a one-to-one corresponding diagnosis and exclusion.

(1)When hang the wrong gear: shake the gear lever and check its swing Angle. If it is beyond the normal range, the fault is caused by the loose coordination between the ball head positioning pin and the positioning groove at the lower end of the gear lever or excessive wear of the ball head and ball hole. If the shift lever of the manual transmission of the flatcar swings 360 degrees, the locating pin breaks.

(2) if the swing angle is normal and still can't be hung or picked off, the fault is caused by the lower end of the gear shift lever pulling out from the groove (the reason for the pulling out is the wear of the lower arc working plate).

(3) Both gears are mounted at the same time: then the fault is caused by the failure of the interlocking device. The difficulty of shifting refers to that the clutch is in good technical condition, but it can not be successfully put into gear when shifting, and the collision sound of gear often occurs. One of this causes was a malfunction of the synchronizer.

Low bed transport trailer reliable parking, pull the parking - brake handle. Start the engine, the engine idles, step on the clutch pedal, change to 1 or reverse, check whether there is noise, whether the shift is smooth. If there is noise or uneven shift, it indicates that the clutch separation of the low bed trailer is not complete.At this time, it is necessary to check the vehicle, including checking the free travel of the clutch pedal, checking the working condition of the clutch, and checking the liquid level of the clutch storage tank. Through these several aspects, we can find out the reason and solve it.


The hydraulic control system of the clutch of the low bed transport semitrailer may enter the air in the pipeline after being overhauled. The air may enter in hydraulic system when add brake fluid. After the air enters, the clutch separation of the low bed conveyer trailer is not complete due to the shortening of the push rod stroke of the master cylinder, that is, the working stroke of the pedal.Therefore, after the maintenance of the hydraulic system or suspected whether the air get into the hydraulic system, it is necessary to exclude the air in the hydraulic system.

The specific exclusion method has the following six points, we will make an analysis one by one:

1) Add the brake fluid in the master cylinder storage tank to the specified height, and raise the low bed transporter trailer.

2) A hose is installed on the vent valve of the working cylinder and connected to a container containing brake fluid.

3) Air exhaust needs two people to work together. One person slowly steps the clutch pedal several times and does not move when he feels resistance. The other person unscrews the release valve until the brake fluid begins to flow out, and then screws the release valve.

4) the number of continuous operation according to the above method several times, until the outflow of the brake fluid no bubbles.

5) After the air is cleared, it is necessary to check again and adjust the free travel of the pedal.

6) This is the last step. Check the height of the liquid level in the liquid storage tank of the main cylinder again. If the height is not enough, add it again.

Pipeline leakage situation:

This is because there is a problem with the brake management system of the low bed semi-trailer. The vehicle cannot be interrupted during the transportation, so the accident will happen. To prevent some of the most common problems, the trailer trainer will often remind you to equip common items, such as raw tape. It is necessary to use raw tape to stick the pipeline at the leak place to solve the leak problem timely.


XII. What are the problems that China has focused on rectifying low bed transport trailers?

According to the regulations of China, the connection mode of low bed semitrailer and tractor should be gooseneck type, but in practice, almost all add a flat plate between the low bed trailer and the tractor, made it the same width from front to back, and even some manufacturers' products can be "after pumping" to increase the volume of transport. The new standards explicitly apply to the "inspection and use" of products.

In fact, because of low bed semi trailers' long body, heavy load, the low bed transport vehicle is popular with users.But in the process of operation, there are many problems such as card problems and security problems.At the same time, the number of low bed semitrailers far greater than other semitrailers, which is unfair to other legitimate vehicles and disrupts the market order. In the industry, there has always been a call for the regulation of low bed semi-trailers. In the future, low bed transporters may face centralized rectification.

one line two axles low bed trailer

XIII. Lightweight low bed semi trailers follow the trend of the market

Light semi trailers not only have certain advantages in their own "lightweight", but also have same economic benefits as ordinary semi-trailers. Because the weight of the light low bed semi-trailer is more than 2 tons less than that of the ordinary low bed semi-trailer, so if the comprehensive calculation comes down a year, light semi-trailer in every transportation will transport 2 tons goods more than of ordinary semi-trailer, the light low bed semi-trailer will be more than the ordinary semi-trailer income tens of thousands of dollars. From the perspective of economic benefits, the future development advantage of SUNSKY Semitrailer is just around the corner.

SUNSKY semitrailer gradually influences the sales market of semitrailer manufacturing industry. Due to the special advantage of "lightweight" of semitrailer, light low bed semitrailer has attracted more and more attention of consumers due to its special advantage of "lightweight". The launch of light semi-trailers has gradually updated the shortcomings of traditional steel semi-trailers in their own weight. With the increasing development of high-tech, ordinary semi-trailers will gradually be "updated and replaced" by light low bed semi-trailers. Therefore, it seems that the future development prospect of light semi-trailers is quite good.

In the future of semi-trailer manufacturing development road, light semi-trailer will be a mainstream product in the trailer manufacturing industry, the future development advantage should not be underestimated,it will be a technical change to the ordinary semi-trailer.

"In the current economic environment, the growth of the commercial vehicle industry remains challenging," SUNSKY boss said,as a result of the overall market demand for raw materials, the price of raw materials has risen, coupled with the price of fuel such as oil and gas.

In recent years, China's sea freight, road freight and container transport and other logistics transport market is increasingly prosperous, prompting the corresponding transport vehicle market demand increases, and as the main vehicle of road transport - semi trailer demand increases, and at present China's transportation semi trailer is still mainly to tipper semi trailer.

4 axles low bed trailer

4 axles low bed trailer

Now semi-trailer in the market is a mass product with low added value, relatively sophisticated skills, and severe product homogenization. Semi-trailer lightweight has become a trend, the manufacturers of lightweight models are just beginning, lightweight semitrailers is a challenge to the traditional semitrailers. If the enterprise can deal with the above problems well,take high quality but low price products as a start, one can quickly become invincible in the semitrailers market.

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