Product information
Trailer vs. Semi-Trailer: Definitions, Differences, and Buying Tips
In road transport, trailers and semi-trailers are familiar vehicle types that play a vital role in moving goods from one place to another. However, not everyone distinguishes these two correctly. To understand “What is a trailer? What is a semi-trailer?” and the importance of both product lines in today’s transport systems, please explore the guide below.
What are trailers and semi-trailers?
Trailers and semi-trailers are non-powered road vehicles engineered with robust structures, purpose-built to carry people or goods and to be coupled to a towing vehicle (tractor). “Trailers and semi-trailers” are also known as “full trailers and semi-trailers.”
What is a trailer?
A trailer is a towed vehicle whose total weight is not imposed on the tractor.
Common trailer types today:
– General-purpose trailer (General purpose trailer): designed and equipped to carry goods.
– Caravan (Caravan): designed as mobile living accommodation.
– Special trailer (Special trailer): engineered and equipped to perform a single, dedicated function.
What is a semi-trailer?
A semi-trailer couples to a road tractor and transfers a substantial share of its total weight onto the tractor.
Popular semi-trailer types:
– General-purpose semi-trailers (General purpose semi-trailer): structures and equipment for carrying goods.
– Specialized semi-trailers (Special semi-trailer): purpose-built for specific cargoes, such as log carriers, low-bed semi-trailers, or fire-fighting semi-trailers.
Trailer vs. semi-trailer
Similarities
– Both are non-powered road vehicles towed by a motor vehicle.
– Both are used for freight transport.
– They move goods from place to place and are common across transport networks.
Trailer vs. semi-trailer
Key differences
| Feature | Trailer | Semi-trailer |
| Axle layout | Axles at the front and rear of the trailer | All axles positioned at the rear section |
| Load transfer | Little to no weight is transferred to the towing vehicle | A significant portion of total weight is supported by the tractor–semi-trailer combination |
| Free-standing | Can stand on its own | Cannot stand without support |
| Towing vehicle | Can be towed by various vehicles | Must be towed by a road tractor |
| Typical use | Short-haul moves in plants, ports, stations, depots | Long-haul freight |
| Examples | Cargo trucks with trailers, passenger vans with trailers, ambulances (with trailers) | Container semi-trailers, tipper (dump) semi-trailers |
Most popular semi-trailer product lines on the market today
Below is a summary of the most popular semi-trailer categories on today’s market, grouped by use case:
Container semi-trailers
Container semi-trailers are the most common, used to move ISO containers – standardized boxes used across sea, rail, and road. A container semi-trailer can be hauled by a road tractor and carry one or more containers.
Container semi-trailer
Tipper (dump) semi-trailers
Tipper (dump) semi-trailers are used for loose commodities such as sand, gravel, or grain. The bed opens and lifts to discharge the load.
Enclosed/cage semi-trailers
Enclosed or cage semi-trailers protect fragile or high-value goods with a surrounding steel frame.
Flatbed semi-trailers
Flatbeds move oversized or bulky cargo such as machinery or trucks. The flat deck can be tarped to protect goods.
Tank semi-trailers
Tank semi-trailers are used to transport liquids such as oil, gasoline, or chemicals, featuring a large integrated tank.
Basic structure of Thaco Trailers semi-trailers
Thaco Trailers is a leading Vietnamese brand manufacturing skeletal, flatbed, and specialized semi-trailers. With modern equipment and production lines, Thaco Trailers builds products to international standards and exports to demanding markets such as the U.S., Australia, and Canada.
Let’s explore the general structure of semi-trailers and what sets THACO Trailers’ designs apart.
Axles, rims, and tires
This is the primary load-bearing system that supports most of the trailer’s weight and enables smooth movement.
Depending on the semi-trailer type, common rim/tire sets include: 8.25×22.5 with 11R22.5 (tubeless), 9.00×22.5 with 12R22.5 (tubeless), 8.00×20 with 11.00R20 (tube-type). THACO Trailers uses FUWA axles rated at 13 tons.
Suspension system
The suspension reduces shock and vibration while driving. THACO Trailers uses FUWA suspension with straight spring seat and 4- or 7-leaf spring. This reduces trailer “hop” during braking compared with curved hangers, while improving braking effectiveness and operational safety.
Main beams
The main beams bear primary loads. THACO Trailers uses high-strength Q345B steel, then applies shot-blasting and ED electrophoretic coating to increase durability and service life. The beams are rigidly connected to form a robust frame.
Landing legs
Landing legs keep the trailer stable when uncoupled. THACO Trailers uses FUWA or Shutsu landing gear with 28-ton dynamic and 80-ton static ratings.
Kingpin
The kingpin links the semi-trailer to the tractor’s fifth wheel. Typical diameters are 50 mm or 90 mm. Choose the kingpin to match payload and the tractor’s fifth-wheel size. At THACO Trailers, kingpins are bolted, allowing removal and replacement when needed.
Braking system
A pneumatic (air) brake system integrated with the tractor provides stopping and speed control.
Electrical system
Supplies power to lighting devices such as front markers, side lamps, rear lamps, combined brake/indicator/fog/reverse lights, and the license-plate light. Typically a 7-pin harness is used, operating at 10–30 V.
Locks
Locking devices secure the trailer to the tractor and, for container models, secure containers. Layout and quantity vary by model.
Other components
THACO Trailers semi-trailers are additionally equipped with side and rear guards, a toolbox, and a spare rim/tire set for operations.
Thaco Trailers – Vietnam’s leading semi-trailer manufacturer
Thaco Trailers – a subsidiary of THACO INDUSTRIES — is among Vietnam’s leading semi-trailer manufacturers, with annual capacity up to 30,000 units. The product range includes:
– Skeletal semi-trailers: Including 20’, 40’, and 45’ skeletal semi-trailers. This is a core export line for THACO INDUSTRIES.
– Flatbed semi-trailers: Including low-bed semi-trailers, 40′ flatbed – 3 axles – 08 twist locks semi-trailers, 45′ flatbed – 3 axles – 10 twist locks semi-trailers, etc.
– Specialized semi-trailers: Including specialized semi-trailers for the automotive sector, livestock carriers, refrigerated semi-trailers… custom-designed to specific customer requirements.
THACO Trailers – Vietnam’s leading semi-trailer manufacturer
The production lines are invested synchronously, meeting the ISO 9001:2015, ISO 14001:2015 quality management system certification. The company operates according to a closed production process, with modern technologies such as: slitting line, fiber laser cutting machine, CNC pressing machine, automatic welding robots, SEMI trailer chain turning equipment, shot blasting booth, ED coating line, automatic powder coating robot assembly line, and inspection line.
THACO Trailers supplies semi-trailers to many international partners. Products meet export standards for the U.S., Australia, Canada, Mexico, Thailand, and more. The company continues expanding exports with the goal of becoming ASEAN’s leading semi-trailer manufacturer.
Outstanding features of THACO Trailers semi-trailers:
- International-standard quality and superior durability
- High payload capacity, suitable for many types of goods
- Competitive pricing
- Diverse models tailored to customers’ specific needs
Factors to consider when choosing a semi-trailer
When selecting a semi-trailer, consider the following:
Purpose of use
First, define the use case clearly. Semi-trailers move various cargo types, including containers, bulk goods, oversized loads, and fragile items. Choose the right semi-trailer type based on the cargo.
Payload capacity
Payload capacity is an important factor to consider when choosing a semi-trailer. The semi-trailer must be able to withstand the maximum payload capacity suitable for the type of goods to be transported. If the payload capacity of the semi-trailer is not enough, it may lead to accidents or damage to the goods.
Dimensions
The size of the semi-trailer also needs to be considered in accordance with the tractor. The semi-trailer must be of the appropriate size to be pulled by the tractor. In addition, attention should be paid to the length of the semi-trailer to ensure that it does not exceed the allowable length of the tractor.
Quality
Select high-quality materials and construction to ensure durability and safety.
Price
Pricing varies by semi-trailer type, quality, size, brand, and more. Balance budget with performance and lifecycle value.
Notes when choosing a semi-trailer
Today, THACO Trailers is a leading and trusted semi-trailer manufacturer in Vietnam. With a team of 1,000 engineers and experts, the company continually improves product and service quality to deliver optimal value to customers.
