Mid axle trailer (commonly referred to as“ in the industry); Mid axle vehicle; In some scenarios, it is commonly referred to as“ Trailer” ）It is a trailer with a special structure, and its core feature isThe towing pin (a key component connecting the towing vehicle) is located in the middle of the trailer wheelbaseInstead of the front end of a traditional semi-trailer or the rear end of a full trailer, this structure gives it advantages in flexibility, load-bearing efficiency, and road adaptability, and is widely used in logistics transportation, passenger car transportation, special goods transportation, and other fields.

 

• frameThe main frame that carries goods is usually welded with high-strength steel and designed as flat plate, rail plate, enclosed, etc. according to the purpose;
• Mid mounted traction deviceThe traction pin and traction frame located in the middle of the frame are used to connect with the traction hook of the traction vehicle (such as the tractor, cargo truck, and traction head), and are the core of force transmission;
• Suspension and wheelsAir suspension or mechanical suspension is commonly used, and the number of wheels is designed according to the load-bearing requirements (commonly 2-axle or 3-axle). Some models are equipped with ABS anti lock braking system and EBS electronic braking system;
• braking systemSynchronized pneumatic or hydraulic braking with the towing vehicle, some models are equipped with retarders to enhance downhill safety;
• Supporting deviceThe support legs (manual or electric) used to support the vehicle body when the trailer is parked, to avoid the traction device being subjected to force.

2、 Main classifications and application scenarios

1. Mid axle freight trailer

• core purposeGeneral cargo transportation (such as household appliances, building materials, daily necessities), especially suitable for; The next kilometer; Or regional logistics;
• structural characteristicsMostly flat or rail type, some are equipped with hydraulic tailboards for easy loading and unloading, with a short wheelbase design (usually 6-10 meters) and a load-bearing capacity of 5-15 tons;
• Advantage scenariosShort distance transportation and narrow road traffic within the city (such as township roads) can be paired with light trucks and medium trucks, with greater flexibility than semi trailers.

2. Mid axle vehicle transport trailer (sedan)

• core purposeThe bulk transportation of passenger cars (sedans, SUVs) and commercial vehicles (light trucks) is the mainstream model in the automotive logistics industry;
• structural characteristicsAdopting a double-layer or three-layer frame design (adjustable height for upper and lower layers), equipped with guide rails and fixing devices (such as wheel stops and straps) to prevent sliding during vehicle transportation;
• Policy ContextDomestic Governance in 2016; Illegal oversized sedan transport vehicles; Afterwards, mid axle sedans became the main force in compliance, with a capacity of 6-10 sedans per vehicle (adjusted according to the size of the model), and can pass the“ Main vehicle+center axle trailer; The combination achieves a longer transportation chain.

3. Mid axle RV trailer (RV trailer)

• core purposeOutdoor camping, long-distance travel, providing users with living functions such as accommodation and cooking;
• structural characteristicsThe body of the vehicle is a closed box, equipped with facilities such as bedrooms, kitchens, and bathrooms inside. It is lightweight (usually 1-3 tons) and must comply with the "Technical Conditions for Motor Vehicle Operation Safety" (GB7258); Travel trailer” Safety requirements (such as equipped with brake synchronization devices and reflective signs);
• Usage requirementsThe towing vehicle must have towing qualifications (marked as“); Quasi total traction mass; ）Drivers are required to hold a C6 driver's license (a new regulation implemented from April 2022 specifically for light center axle recreational trailers).

4. Mid axle special trailer

• core purposeTransport oversized and specially shaped items, such as large equipment, construction machinery, and prefabricated components;
• structural characteristicsAdopting a retractable frame, hydraulic steering wheels, and multi axle design (some up to 5 axles or more), the wheelbase and bearing surface height can be adjusted according to the size of the cargo, and some models are equipped with“ Hydraulic lifting” Function, convenient for loading and unloading heavy objects;
• Application scenariosIn fields such as engineering construction, wind power equipment transportation, and aerospace equipment transfer, it is necessary to handle them in advance; Overlimit transportation permit;.

3、 Core advantages and usage limitations

1. Core advantages

• High flexibilityDue to the proximity of the towing point, the trailer is turning; Followability; Strong, with a small turning radius that can be 20% -30% smaller than semi trailers of the same length, suitable for loading and unloading on narrow urban roads and in residential areas;
• Strong complianceComply with the requirements of the domestic "Limits for Dimensions, Axle Load and Mass of Automobiles, Trailers and Car Trains" (GB1589), especially the "; Main vehicle+center axle trailer; The combination (total length≤ 22 meters) can increase the loading capacity (such as sedan and freight vehicles) without exceeding the limit;
• Low requirements for towing vehiclesSemi trailers require towing vehicles (with saddles), while center axle trailers can be used in conjunction with regular cargo vehicles SUV、 The combination of pickup trucks and other equipment (as long as the vehicle has towing hooks and towing qualifications) reduces the threshold for use;
• Good safetyThe weight is borne by its own wheels, and the towing vehicle only transmits traction force, avoiding the semi-trailer; Head light, tail heavy; The risk of rollover is caused, and most center axle trailers are equipped with synchronous braking systems, resulting in shorter braking distances.

2. Usage restrictions

• Limited carrying capacityDue to its own number of axles and tire specifications, the allowable total mass of a center axle trailer usually does not exceed 20 tons (except for special vehicles), which is much lower than that of a semi-trailer (up to 49 tons) and is not suitable for long-distance or heavy-duty mainline transportation;
• There are requirements for driver operationAlthough it has high flexibility, it is necessary to master when reversing; Reverse steering; Skills (different from semi-trailer reversing logic), beginners are prone to encounter the issue of "ldquo; Shake off the tail;;
• Partial road restrictionsSome cities (such as Beijing and Shanghai) have restrictions on the entry time of mid axle trailers (especially freight vehicles) into the city (such as prohibiting them from entering the main urban area during rush hour), and recreational trailers need to pay attention to the traffic regulations of some highway sections (such as prohibiting trailer traffic in some tunnels and bridges);
• High maintenance costsDue to its unique structure (such as a mid mounted towing device and multi axle suspension), personnel are required for later maintenance, and the price of accessories is higher than that of ordinary trailers.

4、 Key points of relevant domestic policies

1. Size and weight limitsAccording to GB1589-2016, the length of the center axle trailer itself is 12 meters (8.5 meters for recreational trailers); Traction vehicle+center axle trailer; The total length of the car train is 22 meters, and the total mass does not exceed the sum of the quasi towing total mass of the towing vehicle and the total mass of the trailer itself;
2. Driver's license requirementsA center axle recreational trailer with a total towing weight of 4.5 tons requires a C6 driver's license (which can be increased through C1/C2); If the total weight of the car train is greater than 4.5 tons, it is necessary to hold an A2 driver's license for towing freight mid axle trailers;
3. Security configuration requirementsAll center axle trailers must be equipped with ABS anti lock braking system, reflective markings, and side rear protective devices; Travel trailers must also be equipped with parking brake devices and emergency brake devices, and are not allowed to carry passengers (only the driver and passengers accompanying the towing vehicle are allowed);
4. Registration and InsuranceMid axle trailers need to separately apply for motor vehicle registration (obtain license plates) and purchase compulsory motor vehicle traffic accident liability insurance (compulsory traffic insurance). Some regions require the purchase of commercial third-party insurance.

5、 With“ Trailer” Conceptual analysis

• inclusion relationA center axle trailer is; Trailer” One of them, but; Trailer” It also includes full trailers, rescue trailers (such as flatbed trailers used for road rescue), towing trailers (such as small camping trailers), etc;
• Difference points：
  • Mid axle trailer: The towing point is located in the middle and relies on the traction force of the towing vehicle for driving, without power;
  • Rescue trailer: mostly single unit structure, self powered (such as a clearing vehicle), or unpowered but only used for short distance towing of faulty vehicles;
  • Small towing trailers: mostly 1 axle, weighing 1 ton (such as bicycle trailers, small camping trailers), with the towing point at the rear end, showing significant structural differences from center axle trailers.