Semi-trailer truck

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semi-trailer trucks (more commonly half trucks or just " semi ") are a combination of a tractor unit and one or more semi trailers for transporting goods. A semi-trailer is attached to the tractor with a fifth-wheel barrier, with most of the weight borne by the tractor. The result is that both the tractor and the semi-trailer will have a distinctly different design from the rigid trucks and trailers.

This is known as transportation in Canada; semi or single in Australia and New Zealand; semi , , big rig , or eighteen wheel in the United States; and articulated trucks , abbreviated artic , in the United Kingdom, Ireland and New Zealand.

Video Semi-trailer truck

Konfigurasi regional

Amerika Utara

In North America, combined vehicles consisting of powered trucks and one or more semitrailers are known as "semis", "semitrailers", "tractor-trailers", "big rigs", "semi trucks", "eighteen wheels", or " semi-tractor trailer ".

Tractor units typically have two or three axles; built to transport heavy commercial construction machinery may have as many as five, some often raised axle.

The most common cab-tract layout has a front engine, a steering shaft, and two moving axles. Combined the fifth wheel trailer on the most moving tractor forward and rear tractor, to allow adjustment in the weight distribution over the rear axle (s).

Everywhere in Europe, but less common in North America since the 1990s, is a cabin engine configuration, where the driver sits next to, or on top of a machine. With changes in the US to the maximum length of the combined vehicle, the delivery was largely removed from the North American over-the-road service in 2007. Cabovers are difficult to service; for a long time, the taxi can not be lifted on its hinges to a 90 degree incline forward, severely restricting access to the front of the machine.

By 2016, a truck can cost $ 100,000, while diesel fuel costs can be $ 70,000 per year. Trucks average from 4 to 8 miles per US gallon (59 to 29 L/100 km), with fuel economy standards requiring more than 7 miles per gallon of US (34Ã, L/100 km) of efficiency by 2014. Needs power in standard conditions is 170 hp at 55 mph (89 km/h) or 280 hp at 70 mph (113 km/h), and the power usage is somewhat different in other conditions.

Cargo trailers typically have a tandem axle at the rear, each of which has double wheels, or eight tires in the trailer, four per axle. In the US it usually refers to the number of wheel hubs, not the number of tires; the shaft can have single or double tires without legal difference. The combination of eight tires in the trailer and ten tires on the tractor is what causes the eighteen-wheeled moniker, although this term is considered by some truck drivers to be wrong (the term "eighteen wheels" is a nickname for a combination of over- the-road five axle). Many trailers are equipped with a moving tandem axle to allow adjusting weight distribution.

To connect the second one from a double set to the first trailer, and to support the front of the second trailer, a tooth converter known as "dolly" is used. It has one or two axles, a fifth-wheel clutch for the rear trailer, and a tongue with clutch-ring hitch for the front trailer. Each state can better enable longer vehicles, known as "longer combination vehicles" (or LCVs), and allow them to operate on roads other than Interstate.

Types of long-range vehicles include:

• Double (officially "double STAA", known as "set of joints"): Two 28.5 foot (8.7 m) trailers.
• Triples: Three trailers 28.5 feet (8.7 m).
• Turnpike Doubles: Two trailers 48Ã, ft (14.6 m).
• Rocky Mountain Doubles: One trailer 40 to 53Ã, ft (12.2 to 16.2 m) (though usually no more than 48Ã, ft (14.6 m) and one 28.5 ft trailer (8.7 m) (known as "pup").
• In Canada, Double Turnpike is two trailers 53Ã, ft (16.2 m), and Rocky Mountain Double is trailer 50Ã, ft (15.2 m) with pupÃ, 24Ã, ft (7.3 m) ".

The long-term combination vehicle being considered and studied for the US MAP-21 transport bill is a double container. This combination is being studied for potential recommendations in November 2014:

• 40 ft (12 m) Double Turnpike trailer, 148,000 pounds (67,000 kg) GVWR
• 40Ã, ft (12Ãmm) and 20Ã, ft (6.1Ã, m) trailer Rocky Mountain Doubles,  £ 134,000 (61,000Ã, kg) GVWR
• Double foot footprint (6.1 m).

The US federal government, which only regulates the Interstate Highway System, does not specify maximum length requirements (except on car and boat carriers), only minimum. Tractors can draw two or three trailers if the combination is legal in the state. The maximum weight is 20,000 pounds (9,100 kg) on ​​a single shaft, 34,000 pounds (15,000 kg) in tandem, and 80,000 pounds (36,000 kg) of total for each vehicle or combination. There is a maximum width of 8.5 ft (2.6 m) and no maximum height.

Roads other than Interstate are governed by each state, and laws vary widely. The maximum weight varies between 80,000 pounds (36,000 kg) to 171,000 pounds (78,000 kg), depending on the combination. Most countries limit the operation of installing larger tandem trailers such as triple units, double turnstiles, and Rocky-Mountain hills. The reasons for restricting legal trailer configurations include both the security issues and the impracticality of designing and building roads that can accommodate the larger wheelbase of this vehicle and the larger turning radius associated with it. In general, this configuration is restricted to Interstate. Except for these units, multiple settings are not restricted to certain streets over a single setting. They are also not limited by weather conditions or "operational difficulties". The Canadian province of Ontario, however, has weather-related operating limits for the installation of larger tandem trailers.

Europe

The striking difference between tractor units in Europe and North America is that almost all European models are engine cabins (called "advanced controls" in the UK), while the majority of North American trucks are "conventional" (called "normal control" or "bonneted" in the UK ). European trucks, whether straight or fully articulated, have slim faces on the front. This allows shorter trucks with longer trailers (with larger shipping capacity) in the maximum legal maximum length. In addition, it offers better maneuverability and a better overall look for the driver. The main disadvantage is that for repairs on the COE trucks, all cabs have to rely forward to allow maintenance access. In contrast, "conventional" cab tractors offer drivers a more comfortable driving environment and better protection in collisions.

In Europe normally the two rear axles have double wheels, while single or double wheels are used for cargo trailers. The most commonly used combination in Europe is a semi-axle tractor, a lift axle, and a cargo trolley with three axles, one axle lifter, which provides six axles and a total of 22 wheels. This format is now common throughout Europe, due to reduced road loading requirements, especially for bridges. Lifting axles used on tractors and trailers allow trucks to remain legal, but reduce scrub tires and wear while carrying lighter loads by raising the shaft mounted on the highway. For more details, see the United Kingdom, below.

When using dolly, which generally should be equipped with lamps and plates, a rigid truck can be used to pull semi trailers. The dolly is equipped with a fifth wheel whose trailer is combined. Because the doll is attached to a small hitch in the truck, the trailer maneuver associated with the doll differs from the fifth wheeled trailer maneuvers. Supporting vehicles requires the same technique as supporting the usual combination of trucks/trailers, although the dolly/semi installation may be longer, thus requiring more room for maneuvering. Tractor/semi-trailer configurations are rarely used in wood trucks, as this will use two major advantages of having a load weight on the driving wheel, and the crane loader used to lift the ground beam can be mounted on the rear of the truck behind the load, enabling short cranes ( lightweight) to reach both ends of the vehicle without releasing it. In addition, construction trucks are more commonly seen in rigid midaxed trailer configurations, rather than tractor/semi-trailer settings.

United Kingdom

In the United Kingdom, the maximum permissible semi-trailer truck weights, without using the Special Type of Special Order (STGO), is  £ 97,000 (44 t). In order for a 97,000 pound semi-trailer truck to be allowed on the UK highway, the tractor and the semi-trailer must have three or more axles. The lower weighted semi-trailer truck can mean several tractors and the trailer has fewer axles. In practice, such as a second-rate bus and trainer in the UK, there is no legal height limit for semi-trailer trucks; However, bridges above 16.5 feet (5.03 m) do not have marked heights on them. The semi-trailer truck on the Continent of Europe has a height limit of 13.1 ft (4.0 m). Vehicles heavier than 97,000 pounds are allowed on UK highways but are an inseparable burden, which would be classified as abnormal (or too large). The vehicle is required to show the STGO (Special Types General Order) plate on the front of the tractor unit and, under certain circumstances, must travel by official route and have escort.

Most UK trailers have a length of 45Ã, ft (13.7 m) and, depending on the position of the fifth and kingpin wheels, the combined tractor and trailer units will have a combined length of between 50 and 55Ã, ft (15.25 and 16.75 m). Although the Construction and Utilization Rules allow the maximum rigid length of 60Ã, ft (18.2 m), this, combined with the shallow pole and the fifth wheel near the rear of the tractor unit, can provide an overall length of about 75 × ft (22.75 m).

Starting January 2012, the Department of Transport is conducting trials for the longer semi-trailer. This experiment involves 900 semi trailers of 48 ft (14.6 m) long (ie 3 ft (1 m) longer than the current maximum), and more than 900 semi trailer trailers of 51 feet (15.65 m) (ie 7 × ft ( 2.05 m) longer). This will result in the maximum total length of semi-trailer trucks being 57 ft (17.5 m) for trailers along 48 feet, and 61 feet (18.55 m) for trailers along 51 feet. An increase in length will not result in a weight limit of 97,000 pounds exceeded and will allow some operators to approach a weight limit that may have been previously impossible due to the length of the previous trailer. The trial will last a maximum of 10 years. With certain conditions met, the General Types General Order (STGO) allows vehicles of any size or weight to travel on the UK highway. However, in practice the vehicle must travel by a route authorized by the Department of Transport and move under guard. The burden of abnormal loads in the UK is now dominated by private companies, but very large or heavy loads requiring road closures still have to be guarded by police.

In the UK, some semi-trailer trucks have eight tires in three aces on a tractor; this is known as six wheels or "six leggers", either with the center or rear axle having a single wheel that usually directs and the front axle and can be raised when not needed (ie when unloaded or just a light load is being carried, a setting known as TAG shaft when the rear axle, or mid-lift when the central shaft). Some trailers have two axles that have twin tires on each axis; Other trailers have three axles, where one axle can be a lifter shaft that has a super-single wheel. In the UK, two wheels bolted to the same hub are classified as single wheels, therefore a standard six-axis articulation truck is considered to have twelve wheels, despite having twenty tires. The UK also allows semi-trailer trucks that have six tires on two aces; this is known as a four-wheeled vehicle.

In 2009, the Denby Transport operator designed and built a long-term (25.25 m) B-Train (25.25 m) B-Train (Den-B-Double) truck called Denby Eco-Link to demonstrate the benefits of the vehicle, which is reducing accidents on roads and resulting in fewer roads, reduced emissions because a single tractor unit is still in use and no further toll road investment is needed. Furthermore, Denby Transport confirmed that two Eco-Links will replace three standard semi-trailer trucks while, if limited to the current British weight limit of 97,000 pounds, it is claimed Eco-Link will reduce carbon emissions by 16% and still can halve the amount travel required for the same amount of cargo carried in a conventional semi-trailer truck. This is based on the fact that for light but large items such as toilet paper, plastic bottles, cereals and aluminum cans, conventional semi-trailer trucks run out of cargo space before it reaches the weight limit. At  £ 97,000, compared to 132,000 pounds normally associated with B-Trains, Eco-Link also gives less weight per axle on the road compared to a 97,000 lb semi-trailer semi-trailer truck.

The vehicle was built after Denby Transport believes they have found a legal loophole in current UK law to allow Eco-Link to be used on public roads. Relevant rules relate to the Rules and Regulations on the Use of Vehicle Roads 1986. The 1986 Regulation states that "certain vehicles" may be allowed to draw more than one trailer and can reach up to 85 feet (25.9 m). The legal point reported depends on the definition of a "pulling tool", with Denby ready to argue that the second trailer on Eco-Link is one. The Department of Transport believes that this refers to vehicle recovery after an accident or damage, but the regulation does not explicitly state this.

During BTAC performance testing, Eco-Link was rated "excellent" for its performance in maneuverability, productivity, safety and emissions tests, replacing ordinary semi-trailer trucks in many ways. Private trials are also reported to indicate that the Denby vehicle has a 20% shorter stop distance than a conventional semi-trailer truck with the same weight, as it has an additional axle. The active steering system means Eco-Link has a 41-foot (12.5 m) rotary circle, similar to a conventional semi-trailer truck.

Although the Department of Transport advises that Eco-Link is not permitted on public roads, Denby Transport warns Police of previous timing and test drive routes on public highways, and outlines their position in writing to the East Office of Traffic Area. On December 1, 2009, Denby Transport was preparing to drive Eco-Link on public roads, but this was cut short because the Police pulled a semi-trailer truck as it left the gate to test its legality "to investigate... found infringement". Police said the vehicle was unlawful because of its length and Denby Transport was served with notice by the Vehicle Inspectors and Agency inspectors (VOSA) to remove vehicles from the road for inspection. Upon returning to the page, Denby Transport was formally notified by Police and VOSA that the semi-trailer truck was unusable. Both Eco-Link, as well as other B-Trains, have been allowed on UK roads. However, this prompted the Department of Transport to conduct a literature study into a semi-trailer truck, which has resulted in a longer semi-trailer test started in 2012.

Continental Europe

The maximum overall length in the EU and EEA member states is 18.75 m (61.5 ft) with a maximum weight of 40 tonnes, or 44 tonnes when carrying ISO containers. However, the rule limiting semi-trailer to 16.5 m (54 ft) and 18.75 m was filled with a truck carrying a standard 7.82 m (26 m) body with an additional 7.82 m of body behind it as a trailer. The combination of 25.25 meter trucks developed under the EcoCombi brand that affects the name EuroCombi for ongoing standardization efforts where the combination of trucks must be legal to operate in all jurisdictions of the European Economic Area. With a 50% increase in cargo weight, fuel efficiency increased by an average of 20% with relative reduction in relative carbon emissions and with the added benefit of one-third less trucks on the road. The EU Regulations 1996 establishes the European Module System (EMS) as applied in Sweden. The combination words of EMS and EuroCombi are now used interchangeably to indicate the combination of trucks as specified in EU documents; however, regardless of Sweden and Finland, EuroCombi is only allowed to operate on certain lines in other EU member states. Since 1996, when Sweden and Finland officially won final exemption from European Economic Area rules with a combination of 60 tons and 25.25 m (83 ft), all others From 2006, 25.25 combined trailer trucks should be allowed on restricted routes in Germany, following a similar (ongoing) trial in the Netherlands. Similarly, Denmark has allowed a 25.25m combination on certain routes. This vehicle will run a weight limit of 60 tons. Two types to be used: 1) 26 ton truck pulling dolly and semi-trailer, or 2) tractor unit articulated draw B-double, member states gain ability to adopt the same rules. In Italy, the maximum permissible weight (unless exceptional transport is authorized) is 44 tonnes for each type of combination with five axles or more.

Tractor/semi-trailer configurations are rarely used in wood trucks, as this will use two major advantages of having a load weight on the driving wheel, and the crane loader used to lift the ground beam can be mounted on the rear of the truck behind the load, enabling short cranes ( lightweight) to reach both ends of the vehicle without releasing it. In addition, construction trucks are more commonly seen in rigid midaxed trailer configurations, rather than tractor/semi-trailer settings.

Scandinavia

Denmark and Norway allow 25.25m (83Ã, ft) trucks (Denmark from 2008, and Norway from 2008 on selected routes). In Sweden, the allowed length is 24 m (79 ft) since 1967. Prior to that, its maximum length was unlimited; the only limitation is the axle load. What stops Sweden from adopting the same rules as other European countries, when securing road safety, is the national interest of a competitive forest industry. Finland, with the same road safety issue and equally important forestry industry, following it. The change made the truck capable of carrying three log stacks that were cut into lengths instead of two, because that would be a short combination. They have one in the pile along with a crane on a 6ÃÆ' â € "4 truck, and two extra stacks on a four-axle trailer. Gross weight allowed in both countries is up to 60 tons depending on the distance between the first and last axle.

In negotiations that began in the late 1980s before Sweden and Finland entered the European Economic Area and then the EU, they insisted on the exclusion of EU rules citing environmental problems and the transportation needs of the logging industry. In 1995, after entering the union, the rules changed again, this time to allow a truck carrying a standard CEN unit of 7.82 m (26 ft) to draw a standard trailer 13.6 m (45 ft) on dolly, the total length overall 25.25m. Then, a double-B combination begins to be used, often with a 6 m (20 ft) container on B-links and 12 m (40 ft) containers (or two 6 m containers) in a semi-trailer bed. In allowing longer truck combinations, what would take two 16.5m (54Ã, ft) semi-trailer trucks and one truck and trailer 18.75m (62Ã, ft) to transport on the continent can now be handled only by two 25.25 m truck - greatly reduces overall costs and emissions. Prepared since late 2012 and effective in January 2013, Finland has amended its rules to allow the combined maximum legal weight totaling to 76 tonnes. At the same time, the maximum allowed height will increase by 20 cm (8 inches); from a maximum current of 4.2 m (13.8 ft) to 4.4 m (14.4 ft). The effects of this maximum weight increase will cause the roads and bridges in Finland from time to time are highly debated.

However, longer and heavier combinations are regularly visible on public roads; special permits issued for special payload. The Boliden AB mining company has a special license standing for 80 tonnes combination on a select route between inland mines and a processing plant in Boliden, taking 50 ton tons of ore. Volvo has a special license for 32Ã, ¢ (105Ã, ft), a combination of B-trailer-trailer steering that carries two 12 m (40 × ft) containers to and from the Gothenburg port and Volvo Truck plant, all on the island of Hisingen. Another example is the ongoing project En Trave Till (lit. One more stack/pile ) beginning in December 2008. This will allow longer vehicles to further rationalize transport logging. As the project name suggests, it will be able to carry four piles of wood instead of the usual three. The test is confined to the Norrbotten region and the E4 Europe route between the wood terminals in ÃÆ'â € "verkalix and sawmill at Munksund (outside PiteÃÆ'§). This vehicle is a combination trailer truck along 30 m with gross weight exceeding 90 tons. It is estimated that this will provide a 20% lower cost and 20-25% CO2 emissions reduction compared to the usual 60 ton truck combination. When the combination spreads its weight over more axles, braking distances, road usage and traffic safety are believed to be the same or improved with a 90 ton truck-trailer. Under the same program, two types of 74-ton combinations will be tested at Dalsland and BohuslÃÆ'¤n districts in western Sweden: an enhanced combination of trucks and trailers for use in forests and b-doubles for road transport to a factory in Skoghall. In 2012, the Northland Mining company received permission for a 90-ton combination with an extra dolly load for use on the 150 km (93 mi) Kaunisvaara-Svappavaara route, carrying iron ore.

Australasia

Australia

Australia's land transportation has a reputation for using trucks and enormous road carts. This is reflected in the most popular truck configuration that generally has a dual drive axle and three axles on the trailer, with four tires on each axle. This means that a single Australian semi-trailer truck will usually have 22 tires, which is generally more than their counterparts in other countries. Single super tires are sometimes used on tri-axle trailers. The suspension is designed with travel restrictions, which will hold the ream on the road for one blown or flat tire for each side of the trailer, so a trailer can be moved at low speed to a safe place to repair. The super single is also often used on the steering shaft in Australia to allow for greater loading over the steering shaft. Increased loading of steer tires requires permission.

Long haul transport usually operates as B-doubles with two trailers (each with three axles), for a total of nine axles (including steering). In some light duty applications only one rear axle is truck driven, and the trailer may have only two aces. Beginning in July 2007, the Federal Government and the State of Australia allow the introduction of B-triple trucks on certain road networks. B-Triples are arranged differently from conventional streetcar. The front of their first trailer is supported by a turntable on the prime mover. The second and third trailers are supported by a turntable on the trailer in front of them. As a result, B-Triples are much more stable than road carts and handle very well. Correct road railways operate only in remote areas, governed by individual state or territory governments.

In total, the maximum length that any vehicle can articulate (without special permission and escort) is 53.5 m (176Ã, ft), the maximum load may be up to 164 gross tons, and may have up to four trailers. However, heavy restrictions apply to areas where the vehicle can travel in most states. In remote areas like the Northern Territory, great attention should be taken when sharing roads with longer articulation vehicles that often travel during the day, especially the four-trailer trailer.

Articulated trucks that pull one trailer or two trailers (commonly known as "double short") with a maximum overall length of 19 m (62 ft) are referred to as "heavy vehicle general access" and are permitted in all areas, including metropolitan. B-doubles are limited to a maximum total weight of 62.5 tonnes and an overall length of 25 m (82 ft), or 26 m (85 ft) if they are equipped with approved FUPS (Front Underrun Protection System) devices. Double Bs can only operate on the road specified, covering most of the highways and some major metropolitan roads. B-doubles are very common in all parts of Australia including the state capital and on their main routes exceeds the number of single trailer configurations.

The maximum width of any vehicle is 2.5 m (8.2 m) and height 4.3 m (14 ft). In recent years, benefits have been made by some states to allow certain designs of heavy vehicles up to 4.6 m (15 ft) tall but they are also restricted to designated routes. Actually, a 4.6-meter-high B-double should follow two sets of rules: they can only access the allowed paths for B-doubles and for the 4.6 meter tall vehicle.

In Australia, both prime movers and ordinary riders are common, however, the cabin is most commonly seen on the B-double on the east coast where a reduction in total length allows the vehicle to pull longer trailers and thus more cargo than it should.

New Zealand

The New Zealand law governing the dimensions of trucks is under the Vehicle and Regulatory Dimensions issued by NZ Transport Agency. The new rules are introduced effective February 1, 2017. which increases maximum altitude, width and weight of loads and vehicles to simplify regulations, increase the amount of transport carried out and to increase the range of vehicles and trailers available to transport operators.

The general combination in New Zealand consists of a standard semi-trailer, a B-double or a rigid pulling vehicle that pulls the trailer with the drawbar. The maximum length of a standard vehicle for a trailer with one axle is:

• Semi-trailer: 19 m (62 m)
• Simple: 22 m (72 ft)
• Pole: 20 m (66 ft)

Trailers with two axles can reach 20 m (66 ft), including heavy rigid vehicles to pull two trailers. Loads that are too large require, at least, permits, and may require pilot vehicles.

Maps Semi-trailer truck

Construction

Trailer type

There are many types of semi-trailers used, which are designed to transport a wide range of products.

Coupling and uncoupling

The cargo trailer, using a king pin, is connected to a horizontal quick-release clutch device called a fifth wheel or a rotary hitch at the rear of a tug-and-pull machine that facilitates connection and discharge. The trailer truck can not move on its own because it only has wheels on the back: it requires a front axle, provided by a tug, to carry half load load. When the brakes are hard at high speed, the vehicle has a tendency to fold in the pivot point between the towing vehicle and the trailer. Such truck accidents are called "trailer swings", though they are also often described as "folding knives". Jackknifing is a condition in which traction units swing laps into the trailer, and not vice versa.

Braking

The semi-truck uses air pressure instead of hydraulic fluid, to drive the brakes. The use of air hose allows the ease of installation and discharge of trailers from tractor units. The most common failure is fade brakes , usually caused when the drum or disc and brake lining are overheated from excessive use.

Tractor parking brakes and emergency brake trailers are spring brakes that require air pressure to be released. They are applied when air pressure is released from the system, and is released when air pressure is applied. This is a fail-safe design feature that ensures that if the air pressure to one of the units is lost, the vehicle will stop stopping, instead of continuing without the brakes and becoming uncontrollable. The trailer control is coupled to the tractor via two gladhand connectors, which provide air pressure, and power cables, which provide power to any lights and special features of the trailer.

The fun-hand connector (also known as palm coupling ) is an air hose connector, each having a flat draw face and a retaining tab. The faces are placed together, and the units are rotated so that the tabs are interlocked to hold the connectors together. This arrangement provides a secure connection but allows the coupler to escape without damaging the equipment if it is withdrawn, as it can occur when the tractor and trailer are separated without separating the air path first. These connectors are similar in design to those used for the same purpose between rail cars. Two air lines are usually connected to the trailer unit. Main Emergency Airline or presses the trailer air tank and releases the emergency brake, and the second service channel controls the brake application as long as normal. operation.

In the UK, the fast release male/female connectors (red line or emergency), have women in trucks and men in trailers, but the yellow line or service has men in trucks and women in trailers. It avoids clutch errors (not causing brakes) plus connections will not be separated if pulled by accident. Three electric lines will match one street around the primary black, secondary green, and tin ABS, all collectively known as suzies suzie or suzie coils .

Another braking feature of semi-trucks is engine braking, which can be either compression brakes (usually shortened to Jake brakes) or flue brakes or a combination of both. However, the use of compression brakes alone produces a loud and distinct sound, and to control noise pollution, some local municipalities prohibit or restrict the use of engine brake systems within their jurisdictions, especially in residential areas. The advantage of using engine braking instead of conventional brakes is that trucks can descend a long class without overheating their brakes. Some vehicles can also be equipped with hydraulic or electric retarders that have an advantage in quiet operation.

Transmission

Due to the wide range of semi payloads they can carry, they usually have a manual transmission to allow the driver to have as much control as possible. However, all truck manufacturers now offer semi-automatic transmission (manual gearbox with automatic gearshift), as well as automatic transmissions.

Semi-truck transmissions can have at least three forward speeds or as many as 18 forward speeds (plus 2 speed backwards). A large number of transmission ratios means the driver can operate the engine more efficiently. Modern diesel engines on the highway are designed to provide maximum torque within a narrow RPM range (typically 1200-1500 RPM); having more gear ratios means the driver can hold the engine in its optimal range regardless of the speed of the road (the axle axle ratio should also be considered).

A ten-speed manual transmission, for example, is controlled through a six-slot H-box pattern, similar to that in a five-speed car - five front teeth and one reverse gear. Six to ten Gears (and high speed reverse) accessed by Lo/High range dividers; gear one to five is Lo distance; six to ten teeth have a high range using the same shift pattern. A Super-10 transmission, by contrast, does not have a range splitter; using shift "stick and button" shifted (stick shifted 1-3-5-7-9, shifted button 2-4-6-8-10). 13, 15, and 18-speed transmissions have the same basic shift pattern, but include a splitter button to activate the additional ratios found in each range. Some transmissions may have 12 speeds.

Another difference between semi-truck and car is the way the clutch is set. On the car, the clutch pedal is pressed to the floor for every gearshift, to make sure the gearbox is detached from the engine. In semi-trucks with a constant mesh transmission (not synchronized), such as by the Eaton Roadranger series, not only double clutch is required, but brake clutch is also required. The clutch brake stops the rotation of the gear, and allows the truck to be inserted into the tooth without grinding while stationary. Clutch is pressed to the floor only to allow smooth gear when starting from full stop; when the truck moves, the clutch pedal is just pressed far enough to break the torque for a tooth change.

Lamp

An electrical connection is made between the tractor and the trailer via a cable that is often referred to as pigtail . This cable is a bundle of cables in one casing. Each wire controls one of the electric circuitry in the trailer, such as a running light, brake lights, turn signal, etc. The straight cable will break when the rig runs round the corner, so a circular cable is used which retracts this coil when it is not under tension. These scrolls cause the cables to look like pigtails.

In most countries, a trailer or a semi-trailer must have a minimum

• 2 taillights (red)
• 2 stop lights (red)
• 2 lights changed; one for right and one for left, flashing (optional amber; red in North America)
• 2 marks the lights on the back if wider than a certain specification (red, plus a bunch of 3 red lights in the center in North America)
• 2 marks the headlights if wider than a truck or wider than a specific specification (white, yellow in North America)

Wheels and tires

Although double wheels are the most common, the use of two wider single tires, known as super singular, has on each axis become popular among cargo carriers of bulk cargo and other heavy-duty carriers. With increasing efforts to reduce greenhouse gas emissions, the use of super-single tires is getting popular. There are several advantages of this configuration. The first is that the singlet super reduces fuel consumption. In 1999, testing on an oval track showed a 10% fuel savings when a super single was used. This savings is realized because less energy is wasted flexing fewer tire sidewall. Second, the overall weight of the lighter tire allows the truck to load with more load. The third advantage is that the single wheel closes fewer brake units, allowing faster cooling and reduced fading brakes.

One of the main disadvantages of the super singles is that they are not currently widely available as standard tires. In addition, if the tire has to be flat or destroyed, no other tires are attached to the same hub to maintain the dynamic stability of the vehicle, as is the case with double wheels. With double wheels, the remaining tires may be overloaded, but will usually allow the vehicle to stop safely or be pushed to a repair facility.

In Europe, super singles became popular when the weight of the semitrailer rigs allowed to be increased from 38 to 40 tons. In this reform, the trailer industry replaced two 10-ton (22,000-pound) axles with double wheels, with three axles 8 tons (18,000 lb) on single wheel wide. Significant lower pivot weights in super singles should be considered when comparing road wear from single versus double wheels. The majority of super singles sold in Europe have a width of 385 mm (15.2 inches). The standard 385 tire has a legal payload limit of 4,500 kg (9,900 lb). (Note that expensive and specially reinforced tire 385 approved for 5,000 kg (11,000 pounds) does exist, their market share is small, except the installation on the steering shaft.)

Trailers around the trailer

A rapidly growing innovation in popularity is the trailer that is surrounded. The space between the road and the underside of the trailer frame is traditionally left open until it is realized that the turbulent air circling below the trailer is the main source of aerodynamic drag. Three separate skirt concepts are verified by the US Environmental Protection Agency (EPA) to provide fuel savings of more than 5%, and four separate skirt concepts have EPA verified fuel savings of between 4% and 5%.

The round trailers are often combined with Underrun Protection Systems ( underride guards ), greatly enhancing the safety for passenger vehicles sharing their way.

Ignore guard

Technically called Rearguard Protection System (GMS), this is a rigid assembly hanging on the underside of the trailer, which is intended to provide protection for passenger cars colliding with the back of the trailer. Public awareness of this protection increased after the crash that killed actress Jayne Mansfield on June 29, 1967, when her car was at the rear of the tractor-trailer, causing a fatal head trauma. After his death, NHTSA recommends needing a lower guard, also known as the Mansfield bar , an ICC bar , or DOT bumper , but the truck industry in North America slow to improve this security feature. In Europe, underground and rear side protection is mandated in all trucks and trailers with a gross weight of 3,500 kg or more.

The back of the trailer is near the level of the head for an adult who sits in the car, and without a guard downstairs, the only protection for an adult's head like a collision in the back is the windscreen. The front of the car runs underneath the trailer platform rather than making contact through the passenger car bumper, so the car's protective crush zone becomes irrelevant and the airbag is ineffective in protecting the passenger of the car. The underride guard provides a rigid area for the car to contact at the height of the bumper.

In addition to underride guards, tractor trucks can be fitted with the Front Underground Protection System (FUPS) on the front bumper of the truck. The safest tractor-trailers are also equipped with side-side shields, also called the Side Underrun Protection System (SUPS). This additional retention prevents passenger cars from slipping beneath the trailer from the side, such as side or side collisions, or if the trailer is anchored across the street. In addition to safety benefits, this lower guard can increase fuel mileage by reducing air turbulence under trailers at highway speeds.

Another benefit of having a sturdy underride guard is that it can be secured to the loading dock with a hook to prevent a "creep trailer", trailer movement away from the dock, which opens a dangerous slit during loading or unloading operations.

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Semi-truck Manufacturer

Current semi-truck manufacturers include:

United States and Canada

Europe

Asia/Pacific Asia/Pacific

Other locations

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Driver license

Special driver licenses are required to operate a variety of commercial vehicles.

Canada

Regulations vary by province. A license to operate vehicles with air brakes is required (ie, usually Class I, II or III commercial licenses with "A" or "S" support in a province other than Ontario). In Ontario, "Z" support is required to drive any vehicle using air brakes; in provinces other than Ontario, "A" support is for air-braking operations only, and the "S" support is for air brake operation and adjustment. Anyone who holds a valid Ontario driver's license (ie, excludes motorcycle license) with "Z" support may legally drive a combination of trailer-fitted trailers with registered or actual heavy-duty vehicle brakes (ie, including towing - and towed-vehicle) up to 11 tons, which includes one trailer weighing not more than 4.6 tonnes if the license falls below the following three classes: Class E (school bus - maximum 24-passenger or ambulance capacity), F (bus regular - maximum 24-passenger or ambulance capacity) or G (car, van, or small truck).

A Class B (any school bus), C (all urban truck-transit-vehicles or highways), or D licenses (large trucks other than tractor-trailers) allow the holder to drive a truck-trailer combination with the listed- or actual- gross-vehicle-weight (ie, including towing- and towed-vehicle) larger than 11 tons, which includes one trailer weighing not more than 4.6 tons. Anyone who holds an Ontario Class A (or equivalent) license may move any truck-trailer combination with registered heavy vehicle or actual weight (ie, including towing and towing vehicles) greater than 11 tons, which includes one or more many trailers weighing over 4.6 tons.

United States

Semi-trailer truck drivers generally require a Class A (CDL) commercial driver license to operate any combination vehicle with a combined gross weight (or GCWR) rating of more than 26,000 pounds (11,800 kg) if the gross vehicle weight (GVWR) rating of the vehicle drawn ( s) is over 10,000 pounds (4,500 kg). Some states (such as North Dakota) make exceptions to farmers, allowing non-commercial licensees to operate semis within a specified airborne radius from their reporting locations. State exceptions, however, apply only in intrastate trades; the provisions of the Federal Regulatory Code (CFR) can be applied in interstate commerce. Also, persons under 21 years of age may not operate commercial vehicles outside the country where commercial licenses are issued. This limitation may also be reflected by certain countries in their intrastate rules. A person must be at least 18 years old to obtain a commercial license.

In addition, support is required for certain types of cargo and vehicle arrangements and types;

• H - Dangerous Materials (HazMat or HM) - required if the material requires HM plaque.
• N - Tanker - the driver gets acquainted with unique fluid tanker handling characteristics.
• X - Indicating Dangerous Materials and Tanker Support, are incorporated.
• Q - Double & amp; Triples - the license holder can drag more than one snippet.
• P - Bus - Any vehicle designed to carry 16 or more passengers (including driver).
• S - School Bus - Any school bus designed to transport 11 or more passengers (including driver).
• W - Crane Truck

Taiwan

Road Traffic Safety Rules (???????) require a joint vehicle driver license (China: ??????? ) to drive a combination vehicle (Mandarin: ??? ). These rules define a combination vehicle as a motor vehicle pulling heavy trailers, ie a trailer with a gross weight of more than 750 kilograms (1,653 pounds).

Europe

The category of driving license CE is required to drive tractor-trailer in Europe. Category C (? In Greece) is required for vehicles over 7,500 kg (16,500 pounds), while category E is for heavy trailers, which in terms of trucks and buses means each trailer is over 750 kg (1,650 pounds). Vehicles above 3500 kg (7,700 lb) - which is the maximum limit of license B - but below 7,500 kg can be driven by a C1 license. Buses require license D (? In Greek). A registered bus for no more than 16 passengers, excluding drivers, can be driven under D1 license.

Australia

Truck drivers in Australia need a supported license. This support is gained through training and experience. The minimum age to hold an approved license is 18 years, and/or must have an open (full) driver's license for a minimum of 12 months. Here is a heavy vehicle license class in Australia:

• LR (Light Rigid) - LR Class includes a rigid vehicle with GVM (gross vehicle mass) of over 4.5 tons but no more than 8 tons. Any trailers that are withdrawn should be no more than 9 tons of GVM. Also includes vehicles with up to 8 tons of GVM that carry more than 12 adults including drivers and vehicles in Class C.
• MR (Medium Rigid) - The MR class includes a rigid vehicle with two axles and a GVM of more than 8 tons. Any trailers that are withdrawn should be no more than 9 tons of GVM. Also includes vehicles in Class LR.
• HR (Heavy Rigid) - The HR class includes a rigid vehicle with three or more axles and a GVM of more than 15 tons. Any trailers that are withdrawn should be no more than 9 tons of GVM. Also includes articulated buses and vehicles in the MR Class.
HC (Combination Weight) - HC Class includes heavy-duty vehicles such as prime movers pulling semi-trailers, or rigid vehicles pulling trailers with GVM over 9 tons. Also includes vehicles in the HR Class.
• MC (Multi Combination) - The MC class includes multi-combination vehicles such as road carts and B-double vehicles. Also includes vehicles in Class HC.

In New Zealand, heavy vehicle drivers require a special license, referred to as a class. A Class 1 license ( car license ) will allow driving any vehicle with GrossWaden Weight (GLW) or 6,000 kg (13,000 pounds) Gross Combination Weight (GCW) or less. For other types of vehicles, classes are separately licensed as follows:

• Class 2 - Medium Rigid Vehicle: Any rigid vehicle with GLW 18,001 kg (39,685 lb) or less with light trailer 3,500 kg (7,700 pounds) or less, any combination vehicle with GCW 12,001 kg (26,458 Â £ lb) or less, any heavy vehicle weighing not more than two aces or Class 1 vehicles.
• Class 3 - Medium Combination Vehicle: Any combination vehicle from GCW 25,001Ã, kg (55,118 lbs) or less, or any Class 2 vehicle.
• Class 4 - Heavy Rigid Vehicle: Any heavy vehicle, any combination vehicle consisting of heavy vehicles and light trailers, or Class 1 or 2 (but not 3) vehicles.
• Class 5 - Combination Weight Vehicle: Any combination vehicle of any weight, and any vehicles covered by the previous class.
• Class 6 - Motorcycles.

More information about the New Zealand licensing system for heavy vehicles can be found at New Zealand Transportation Agents.

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Role in trading

Modern semi-trailer trucks often operate as part of domestic or international transport infrastructure to support cargo shipments in containers.

Different types of flatbed railway track trains are modified to hold cargo trailers or containers with wheels or without. This is called Intermodal or support . This system allows cargo to switch from highway to rail or vice versa with relative ease by using crane gantry.

Source of the article : Wikipedia