When to Use Semi Trailer Tank？

Trailer vehicle without a front axle

A semi-trailer is a trailer without a front axle. The combination of a semi-trailer and a tractor truck is called a semi-trailer truck (also known simply as a "semi-trailer", "tractor trailer", or "semi" in the United States).[1]

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A large proportion of a semi-trailer's weight is supported by a tractor unit, or a detachable front-axle assembly known as a dolly, or the tail of another trailer. The semi-trailer's weight is semi-supported (half-supported) by its own wheels, at the rear of the semi-trailer.[2][3][4][5] A semi-trailer is normally equipped with landing gear (legs which can be lowered) to support it when it is uncoupled. Many semi-trailers have wheels that are capable of being totally dismounted and are also relocatable[6] (repositionable) to better distribute load to bearing wheel weight factors.[7] Semi-trailers are more popular for transport than full trailers, which have both front and rear axles. Ease of backing is cited as one of the semi's chief advantages. A road tractor coupled to a semi-trailer is often called a semi-trailer truck or "semi" in North America and Australia, and an articulated lorry or "artic" in the UK.

Semi-trailers with two trailer units are called B-doubles (Australian English) or tandem tractor-trailers,[8] tandem rigs, or doubles (American English). Other terms used are "B-train" or (when there are three or more trailers) "road train". A double-trailer combination is possible with the use of a dolly, or "converter dolly" (Australian and American English), essentially one to three additional axles placed under the front of a second semi-trailer. The first semi-trailer is connected to the power unit using the tractor's fifth wheel coupling while the converter dolly, already attached to the second semi-trailer, is connected to the first semi-trailer with a drawbar. In Australian English, the tractor unit is called a "prime-mover", and the combination of a prime-mover and trailer is known as a "semi-trailer", "semi" or single. Some popular manufacturers of tractor trucks are Kenworth, Iveco, Freightliner, MAN, Scania, Mercedes-Benz, DAF, Renault Trucks, Volvo, Peterbilt, Mack and Western Star.

Properties

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Semi-trailers were invented by August Fruehauf in .

Road tractors and semi-trailers are responsible for carrying a large proportion of cargo. With 1,170,117 million tonne-kilometers transported this way in the European Union, including the UK, road tractors and semi-trailers are 77.6% of the total tonne-kilometers transported in , according to Eurostat.[9]

In road haulage, semi-trailers predominate over full trailers because of their flexibility. The trailers can be coupled and uncoupled quickly, allowing them to be shunted for loading and to be trucked between depots. If a power unit fails, another tractor can replace it without disturbing the cargo.

Compared with a full trailer, a semi-trailer attached to a tractor unit is easier to reverse, since it has only one turning point (the coupling), whereas a full trailer has two turning points (the coupling and the drawbar attachment). Special tractors are known as shunt trucks or shuttle trucks can easily maneuver semi-trailers at a depot or loading and unloading ferries. These tractors may lift the coupling so the trailer legs clear the ground.

A rigid truck and full trailer are articulated inside the cargo area length, so a semi-trailer can have a longer continuous cargo area. Because of this, a semi-trailer can haul longer objects, (logs, pipe, beams, railway track). This depends on the legislation; in some European countries, a full trailer can be as long as a semi-trailer. However, since a rigid truck is longer than a semi-tractor, this increases the overall length of the combination, making it less maneuverable.

For heavy haulage or for increased manoeuvrability, some semi-trailers are fitted with rear-wheel steering, controlled electro-hydraulically. The wheels on all or some of the rear axles may be turned through different angles to enable tighter cornering, or through the same angle (so-called 'crab' steering) to move the rear of the trailer laterally.

Couplings

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The two types of couplings are fifth-wheel coupling and automatic. In some applications, no separable coupling is fitted, and the trailer is bolted to the tractor unit, using a bearing, and rocker feet as are used under a fifth wheel skid plate.

Fifth-wheel coupling

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The towing vehicle has a wide coupling plate known as a fifth-wheel coupling bolted onto its chassis, on which the semi-trailer rests and pivots. As the tractor reverses under the trailer, a kingpin under the front of the trailer slides into a slot in the skid plate, and the jaws of the fifth wheel close onto it. The driver has to raise the trailer legs manually and couple the airbrake lines and electrical cables. Some low-set trailers such as lowboys/low-loaders and car transporters have electrically powered landing gear due to the necessarily low clearance prohibiting conventional landing gear.

Types

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Different types of semi-trailers are designed to haul different cargoes.

Common widths are 8 ft (2.44 m),[10] and 2.6 metres (102.36 in).[11] Generally speaking, most North American type trailers use two axles with dual-tire hubs totaling 8 wheels, while most European type trailers use three axles with single-tire hubs totaling 6 wheels, with one of the axles being able to be lifted for lighter loads and saving on tire, brake, and axle wear. Nearly all sufficiently tall modern trailers are equipped with a rear underride guard to prevent cars from passing beyond the rear edge of the trailer, and most also have side underride guards for the same reason. There are also other smaller differences with regards to kingpin depth, lighting, door locks, et cetera, though most purpose-built tractor trucks can carry most types of trailer regardless of which continent it was built on and the differences therein.

• Box or van trailers are the most common type. They consist of a metal box on wheels with some doors on the back, though some offer additional access doors on the sides. Standard lengths in North America are 28 ft 0 in (8.53 m), 32 ft 0 in (9.75 m), 34 ft 0 in (10.36 m), 36 ft 0 in (10.97 m), 40 ft 0 in (12.19 m), 45 ft 0 in (13.72 m), 48 ft 0 in (14.63 m), 53 ft 0 in (16.15 m) and 57 ft 0 in (17.37 m).[11] Due to maximum length regulations and the need to maximize cargo within said regulations, almost all European semi-trailers are 13.60 m (44 ft 7+7⁄16 in) in length.
• Bus-bodied trailers are hitched to a tractor unit to form a trailer bus, a simple alternative to building a rigid bus.
• Car carrier trailers carry multiple cars, usually new cars from the manufacturer. In the US and elsewhere, car carriers often carry used vehicles as well. Similar variants can carry forklift trucks, light commercial vehicles, and agricultural tractors. Single-deck versions are used for larger vehicles.
• Conestoga trailers are a special form of a flatbed trailer with a flexible retractable roof and siding used to carry large pieces of equipment that can only be lifted by an overhead crane, but which also need protection from the weather during transit.
• Curtain siders or tautliners are similar to box trailers except the sides are movable curtains made of reinforced fabric coated with a waterproof coating. To put it another way, it is basically a flatbed trailer with additional aerodynamic and weather protection as well as greater load security. They generally have a restraining system of straps and buckles every foot (30 cm) or so to keep the curtain tight and adverse to the elements. Also, some have removable gates mounted into the trailer, to help reinforce the load and prevent bulges. The purpose of a curtain sider is to combine the security and weather resistance of a box trailer with the ease of loading of a flatbed. Curtain siders are one of the most common trailer types in Europe.
• Drop-deck trailers (also called step deck, or step-frame trailers) have a floor that drops down a level once clear of the tractor unit; the most common types of drop-deck trailers are flatbeds and curtain siders.
• Double deckers or deckers have either a fixed, hinged, or moveable second floor to enable them to carry more palletized goods. In general, a double-decker can carry 40 pallets, as opposed to 26 for a standard trailer. Double-deck trailers are generally a step-frame construction with the majority being either box or curtain siders, with box trailers having either a fixed or movable (floating) deck, and curtain sides having either a fixed or hinged second deck; this hinged second deck generally swings into a position down the length of the trailer and can be divided into two or three sections to allow greater load flexibility. In Australia and New Zealand, they are known as mezzanine trailers or mezz-decks for short.
• Dry bulk ("British" powder tankers) trailers resemble big tankers but are used for cement, sand, barite, flour, and other dry powder materials.
• Dump trailers ("British" tippers) are trailers in which one end can be raised to allow the cargo (often building materials or agricultural produce) to slide out the other end. Commonly, they are hinged at the rear and raised at the front, but side-unloading dump trailers also are used.
• Flatbeds, or flat decks, consist of just a load floor and removable side rails and a bulkhead in front to protect the tractor in the event of a load shift. They can haul almost anything that can be stacked on and strapped down.

• Hopper bottoms or grain hopper trailers are usually used to haul grain, but can be used to haul other materials.
• Inloaders are used to transport glass panes on stillages. They feature an open bottom to maximize loading height and the entire trailer can be lifted and lowered during loading, to allow safe loading of fragile glass panels.[12]
• Intermodal trailers are similar in frame design to box trailers, but without any sort of integral cargo-carrying ability as they are designed to carry a variety of standard intermodal containers
• Live bottom trailers have a conveyor belt on the bottom of the trailer tub that pushes the load material out of the back of the trailer. The tub does not have to be raised to deposit the materials.
• Livestock trailers are used to haul livestock such as cattle, horses, pigs, sheep, etc. Commonly, they have two levels (or three for hogs) to maximize capacity.
• Lowboy ("British/Australian" low-loader) trailers are a type of flatbed in which the load floor is as close to the ground as possible, most commonly used to haul heavy equipment, cranes, bulldozers, etc.
• Refrigerator trailers are box trailers with a heating/cooling unit (reefer) attached and insulated walls, used for hauling produce, frozen foods, meat, flowers, etc. Not quite as common but they are also produced in tautliner models with thicker curtains to sustain temperature.
• Refrigerator tank trailers are well insulated or refrigerated to haul bulk liquid foods, such as liquid sugar, water, wine, milk or juices.
• Semi-trailers with sidelifters have a hydraulic crane mounted at each end of the chassis allowing for the loading and unloading of shipping containers without the need of a forklift or other container-handling equipment. Also known as a sideloader.
• Side bay trailers have a series of roll-up or panel doors down each side. Each door opens into individual compartments. These trailers are most commonly used in the beverage distribution industry.
• Tank chassis or tank trailers are used for hauling liquids such as gasoline and alcohol, or various types of gases. They are similar in principle to intermodal trailers but with a very different frame intended to be attached to a liquid or gas tank, hence the name. Some are designed with a lowered centre of gravity to ensure greater stability. Generally bottom loaded with the ability to recover any waste vapor for safety reasons.
• A "frac" tank trailer has a single and fixed axle, and is typically used during hydraulic fracturing at oil wells or for petrochemical industries. It is shaped like a wedge, and when it is unhitched, its bottom side lies flat on the ground.
• "Wing" trailers are mostly found in Japan and are something of a hybrid between a curtain sider and a box trailer, with rigid, motorized gull-wing doors in place of the fabric curtains. Also found as part of a rigid box truck.

Tank trailer

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A tank trailer is a semi-trailer specifically designed to carry liquids, fluids and gases.[13]

Gallery

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• Trailer types
• Box trailer (US)
• Curtain sider trailer (EU)
• Semi dump trailer (EU)
• Flatbed trailer (Iran)
• Live bottom trailer (US)
• Glass inloader trailer (Germany)
• Lowboy (US)
• Refrigerated trailer (UK)
• Sidelifter (New Zealand)
• Tank trailer (Japan)
• Gullwing trailer
• 53 foot container turnpike doubles
• Tank trailer
• French logging truck

See also

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• Transport portal

References

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Tank trailers are key equipment for transporting hazardous materials, ensuring the safe delivery of substances such as oil and chemicals. Their role in industry, agriculture and commerce is becoming increasingly important as the global economy and energy demand grows. These trailers incorporate advanced designs and technologies, such as multi-compartment and vapour recovery systems, to effectively reduce the risk of leaks, explosions and corrosion. As a specialist manufacturer, Truckman Auto offers a wide range of tank trailers to meet different transport needs. There is no substitute for a tank trailer in transporting hazardous materials, and each type has its specific purpose. In this article, we will introduce the types of tank trailers, selection points and safety measures in detail to help you improve transport efficiency and safety.

Tank trailer is a special vehicle designed for transporting dangerous goods. It is widely used in industrial, agricultural and commercial fields, mainly undertaking the task of transporting oil, natural gas, chemicals, food liquids and bulk materials to ensure the safe delivery of goods.

This type of trailer adopts a variety of design structures to adapt to different needs. The baffle type has a perforated internal divider to minimise liquid sloshing. The bulkhead divides the tank into separate storage compartments for easy separation of different cargoes. Smooth-bore tanks are smooth and barrier-free, easy to clean and suitable for single-category transport.

The choice of tank material has a direct impact on transport safety. Lightweight aluminium reduces deadweight. Stainless steel offers high corrosion resistance. Carbon steel is known for its high strength and durability. A reasonable combination of different materials can improve transport efficiency and safety.

According to the differences in transport objects, tank trailers are also subdivided into four professional categories: liquid tankers, gas tankers, powder material tankers and bulk cement trailers. Reasonable selection can not only improve the economic efficiency of transport, but also ensure compliance with the strict safety regulations for the transport of dangerous goods.

Small Mobile Tanker: Small Mobile Tanker 1,000-3,000 gallon capacity design, suitable for pickup truck towing. Flexible, suitable for farm irrigation, construction site oil supply and emergency response in disaster areas, etc. It can enter areas that are difficult to reach by large vehicles.

Gas Transport Semi-trailer: Gas transport semi-trailer adopts high-pressure carbon steel tank to transport LPG/LNG and other gas fuels. Equipped with multiple safety valves and pressure control systems, it is commonly used for LPG distribution in residential areas to meet the needs of domestic and industrial/commercial gas consumption.

All types of tanker trucks are designed for specific transport needs, with differentiated features in material selection, safety configuration and functional design, which together form an important part of the modern logistics and transport system.

The design and capacity of a tank trailer directly determine the safety and efficiency of dangerous goods transport. Below are the key features to ensure efficient and stable cargo transport.

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Baffle Design: Reduces liquid shaking and improves driving stability through perforated bulkheads. Commonly used in fuel and chemical trailers to prevent liquid surge during transport.

Bulkhead design: Separates the tank into multiple storage compartments to avoid cargo mixing. Ideal for food-grade and crude oil trailers where multiple liquids can be transported at the same time.

Smooth-bore design: Smooth interior without dividers for easy cleaning and sterilisation. Suitable for single bulk materials such as powdered cement, ensuring smooth unloading.

Stainless steel material: corrosion-resistant and conforms to food hygiene standards, prolonging service life. Widely used in food and chemical trailers to ensure cargo purity.

Aluminium: Lightweight design improves load efficiency and fuel economy. Commonly used in fuel trailers to reduce transport costs.

Carbon Steel: Tough and pressure resistant, withstands high temperature and pressure conditions. Suitable for gas and asphalt trailers to ensure structural strength.

Small Capacity Range: 1,000 to 3,000 gallon capacity for short-distance local distribution. Commonly used in mobile trailers for flexible service to job sites or disaster areas.

Large Capacity Range: Capacities of 5,000 to 11,600 gallons for long-haul needs. Used in fuel and chemical trailers to support bulk transport.

Dry Bulk Capacity Range: Capacities from 560 to 3,120 cubic feet designed for bulk materials. For powdered cement trailers to ensure efficient loading and unloading.

Choosing the right tank trailer requires a number of factors to be considered, both to ensure safe transport and to achieve economic efficiency. Here are the key points to help you make the best choice for your needs and budget:

Cargo: Defining the type of cargo to be transported is the first step. Food-grade trailers are suitable for milk, fruit juices, etc. Chemical trailers are suitable for nitric acid, ethanol and so on. Fuel trailers are for petrol and diesel. Choosing the right trailer can effectively prevent pollution and safety hazards.

Capacity: The capacity of a tank trailer determines transport capacity and cost. Capacity ranges from 1,000 gallons to 11,600 gallons, and price increases with load capacity. Choosing the right model for your volume and budget ensures efficient operation.

Distance: Distance is also an important consideration. Short distance deliveries (e.g., local job sites) can be made with a small trailer. Long-distance transport (e.g. cross-city fuel) requires a large-capacity trailer. When transporting long distances, efficiency and durability are important considerations.

Safety equipment: Dangerous goods transport requires that trailers are well equipped with safety systems. Submarine, emergency shut-off and overflow valves prevent leaks; pressure relief valves are used to manage pressure; and fire extinguishers respond to fires. Ensuring that the trailer meets DOT standards enhances overall safety.

Industry Suitability: Different industries have different needs for trailers. Agriculture typically chooses water tanks or small trailers; the construction industry requires powdered cement or asphalt trailers; and the energy industry relies on fuel and gas trailers. Choosing the more appropriate equipment for the industry helps to optimise transport efficiency.

Regulatory Requirements: Regulatory compliance is critical. Food trailers need to meet FDA sanitation standards, and chemical and fuel trailers should follow DOT-406 or 407 specifications. Also, make sure the trailer and driver are legally qualified (e.g., CDL) to avoid penalties.

Tank trailer maintenance and safety measures are directly related to the reliability and safety of hazardous materials transport. The following are key points to ensure trailer performance and compliance.

Tank cleaning: Clean the inside of the tank once a month to remove dirt and debris. Food-grade trailers need to be thoroughly sanitised and chemical trailers need to be rinsed of residue to prolong service life and ensure cargo quality.

Regular inspections: Check valves, hoses and sumps every three weeks to confirm no leaks or wear. Annual comprehensive testing, including brake systems and safety equipment, ensures compliance with DOT standards.

Safety equipment maintenance: test subsea valves, emergency shut-off valves and pressure relief valves monthly to ensure proper function. Check fire extinguishers for expiration dates and keep them readily available to address fire risks.

Work area safety: No matches, lighters or open flames are allowed in the work area. Electrical equipment needs explosion-proof certification to avoid accidents caused by static electricity or sparks.

Standardise the use of tools: use copper or alloy spanners when overhauling to avoid sparks caused by knocking iron tools. Ensure safe operation and reduce the risk of explosion.

Driver training: Drivers need to receive dangerous goods transport training, updated annually, to master the loading and unloading process and emergency handling. Hold CDL certification to ensure compliant operation.

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