American truck simulator transmission differences

American truck simulator transmission differences DEFAULT
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How Many Gears Can this Crazy Thing Have?!?
I think the first thing people notice when they first start looking at manual semi transmissions is the number of gears there are. You might look at an Eaton Fuller 18 speed and say to yourself, "I have 6 gear positions and there are 18 gears!". In fact, there are even some trucks in real life that have up to 24 gears. So how is this possible? How can we get 18 gears out of only 6 positions?
This comes from the way a truck transmission is set up. Let's continue our example of the Eaton Fuller 18 speed. In actual fact there aren't 18 gears in an Eaton Fuller 18 speed for one. It's actually 5 forward gears which are then split in half with what's called a splitter. Then there is a high range and a low range that when switched gives you another 4 forward gears which are then, again, split into high and low.
So how do we then magicly split these gears in half and put them into low and high range? This is where are our control settings within the game come in. In our control settings (see images below) there are two very important hot keys that we have to set up. One is labeled "Shifter Toggle: 1" and the other is labeled "shifter toggle: 2". These buttons are going to be used to get all those lovely gears that a gearhead like myself loves. In the next section I will explain using these keys.

Control Settings Within The Game:
Using Splitter and Range Buttons
So I've shown you in the last section what allows us to get all these gears on our truck. Now it's time to explain how to use them. The first thing I would like to say is on where to map these gears. You basically want to put these buttons somewhere that you can reach easily with one hand on the wheel and one hand on the shifter. "Why", you may ask? Well, there are times when cornering or maneuvering that you are going to need to press those buttons with one hand on the shifter and one hand on the wheel.So let's jump right into how we shift a manual gearbox in a semi. It's worth noting that I'm describing this in general terms with no specific transmission in mind. I will explain specific transmissions further in this guide.

Step 1: The first time you load into the game every time the gearbox is going to be set to low range and the splitter will be in low. So if you put it into whatever gear position is gear 1 it will be gear 1L (depending on transmission of course).

Step 2: Press your clutch in and put your shifter where first gear is.

Step 3: As you press in the on your accelerator slowly as you slowly let out on the clutch to start the truck moving.

Step 4: When your RPMs reach between 1500 and 1800ish press in on the clutch as you hit your "Shifter Toggle: 2" known as your splitter and then let out on the clutch. This will split the gear into high.

Step 5: Again, as your RPMs reach the magic numbers you want to depress the clutch, hit your splitter again and shift into where gear 2 is which will put you into 2L.

Step 6: As your RPMs reach the magic numbers you again press in on the clutch and hit your splitter button putting you into 2H.

Step 7: For brevity sake we are going to say that you continue this pattern until you run through all your gears in the bottom range (don't worry I will explain this further in individual transmissions)

Step 8: After you have run through the entire bottom range you would then depress your clutch, put your splitter into low, hit you "Shifter Toggle: 2" also known as your range and shift into where your gear 1L was. This will put you into your first low gear of the high range.

Step 9: You then just go through steps 1 - 6 again until you reach your final gear. What could be any easier? =P.
How to Figure Out a Specific Shift Pattern
So I've gone through the basics of how a semi shifts and how we get all those gears. Now I thought I would cover how to figure out a specific gear pattern. There's a couple of different ways you can go about this depending on whether you are adept at reading a shift schematic or not. If you can't read a shift schematic, fear not, I'll go into that as well. If you can't or don't want to mess with a schematic or can't find one for your specific transmission you can always just play with the truck and figure out the pattern.

How to read a gear schematic
So I thought I would begin with how to read a gear schematic. In the later sections on each transmission I will include a schematic that you can peruse to your hearts content. However, it helps if you can read the darn things right? For an example I will start by showing you the Eaton Fuller 18 speed schematic and then explain it's contents.

Ok so let's have a closer look at what's being displayed here. First off, each box shows the position on the H-shifter so the upper-left box is the upper-left shifter position. Everything that you see displayed in purple will be a gear that's in the low range. Everything that is shown in white will be what's in the high range. The letters you see displayed next to the numbers or the "R" in the case of reverse is denoting whether there is a high or low split for that gear.
So let's look at our upper-left box and see what information we can glean from it. First we notice that there are 4 reverse gears on it. We have a "R" in both our low and high range and then beside each of those "R"s we can then see nomenclature for R1L and R1H in the purple box and then for R2L and R2H in the white box. We can then look at the other gear positions and see, in the same manner, what gears are in that position.

Stick It In A Slot and See What Happens!

So let's say I don't really like this whole schematic thing. Who wants to have to look at a bunch of boxes and numbers? I just want to drive the darn truck! Well, my friend, there is another way to figure out a gear pattern. You can just sit in your dealership with the clutch in and start throwing that stick in holes. After a few times of flipping your range and hitting your splitter you'll eventually (let's hope anyway) figure out what goes where. It's kinda like your first time, well ...... we'll just leave that one alone.
Shifter Layout Behavior & Fast Split Options
Shifter Layout Behavior & Fast Split Option
You may have noticed there are a couple of options below your “Shifter Layout” option. I thought I would go through what these options allow you to do since a lot of people are unsure what they do. The first option right below “Shifter Layout” is “Shifter Layout Behavior”. There are 3 different options you can set this to: “Simple”, “Simple + Warning Sound” and “Advanced”.

Simple: The simple setting does pretty much what you expect it to do. It simplifies the shifting of the truck. You won't grind gears shifting at all and can pretty much shift as fast as you want and whenever you want.
Simple + Warning Sound: The Simple + Warning Sound option is sort of a step up in the complication of shifting a truck. If you try to initiate a shift too fast, like you would a car, the gears will grind on you. You can still initiate a shift at whatever RPM you choose unlike a real truck, but you will grind gears if you try to just slam through gears very fast.
Advanced: The Advanced setting does a couple of different things. The first thing is that, just like with simple + warning sound, your gears will grind if you try to initiate shifts too fast. It's still unlike a real truck in that you don't have to RPM match but if you try to go through gears too fast you will grind them. The second thing this allows us to do is set our “Shifter Fast Split Option (Advanced Only)”.

Shifter Fast Split Option (Advanced Only): If you set your setting to advanced you'll see this option right below your “Shifter Layout Behavior” option. This option allows you to set four different advanced options to split your gears, “Never”, “Clutch Press”, “Throttle Release” and “Clutch or Throttle”. Depending on how you set this up you can do what's called fast splitting your gears. A fast split is where you can select your gear splits ahead of time and then do one of the previously mentioned options to split your gears from low to high or high to low. European trucks use a different setup then U.S. Trucks which I'll explain below.

Never: The name says it all. You will never be able to do a shift fast split. Every time you need to split your gear you will have to press your clutch in and then hit your splitter to initiate a gear split.
Clutch Press: This is the system that European trucks use. Let's say I'm in 4th gear and I'm close to ready to splitting my gear into 4 high. I can go ahead and hit my splitter beforehand and it won't split the gear until I clutch in to split the gear.
Throttle Release: This is sort of the system that U.S. Trucks use although the last option is more accurate to U.S. Trucks. With the Throttle Release option you can select your gear splits ahead of time, just like as in clutch press, but it won't initiate the shift until you let up off the gas. You don't have to use the clutch at all to split your gears.
Clutch or Throttle: This is pretty much the system that U.S. Trucks use. You can select your splits ahead of time and it won't split the gear until you either clutch in or let out on the throttle.
Speed Matching with a Manual Transmission
So what do I mean within the confines of the game as to what speed matching is? Speed matching, as I'm explaining here, in it's basic essence is knowing what gear I need to have my truck at, at a certain speed to either achieve slowing of the truck or to be able to find the right gear when making a sudden stop or something to get back going again. There are, of course, all these rules that you have to follow when speed matching. Just be thankful that you don't have to do the math on gear ratios to figure it out like you do in real life.
The first thing about speed matching is to know your RPM range. We know that a truck get's it's best power to torque ratio between 1,000 and 1,800 RPMs for most trucks with the exception being the DAF and Scania trucks which go up to about 2,000 RPM at the high range. So what does the best power to torque ratio mean? Boiled down to it's very essence it's when the truck's engine is most efficiently transferring power to the transmission which is then most efficiently transferring that power to the wheels. This means that the truck is getting the most power to the wheels with the least amount of effort. It couldn't be much more simple.
In the video below I explain how to do this but I'll also describe it here if you don't want to watch another video.

1. Start out in your first gear and accelerate to 1,000 RPM and make a mental or physical note of what MPH/KPH you are at. This is your low end of the power range.
2. Accelerate to 1,800 RPM and make note, again, of what MPH/KPH you are at. This is the high end of your power range.
3. Shift into your next gear and slow down until you are at 1,000 RPM and make a note of your speed again.
4.You continue this pattern until you have a mental or physical note of where every gear in your transmission has been gone through.

You'll notice a lot of these gear ranges overlap and that's normal. Especially with half gears there is a very small change in your RPM to Speed. This means you don't have to worry about grabbing the exact gear if you are making a down shift from having to do a sudden stop or something. For instance I know that I can have my Volvo 12+2 with the 750 engine in it in 5L-5H-6L or 6H to be right around 45 to 55 KPH. Just as long as you know the approximate gear range you need to be in you should be able to find your gears pretty easily. After a while it becomes something you don't even really have to think about.
Eaton fuller 10 Speed Transmission
First off we can see that there are no gear splits at all, every gear is in either low range or high range. We can see that we have a Reverse in our low range and a reverse in our high range. Gears 1 - 5 are all in the low range. Gear 1 is in the lower left position on the H-shifter, gear 2 is in the upper middle, gear 3 the lower middle, gear 4 upper right and then gear 5 being in our lower right.
Going into high range we can then access gears 6 - 10. Gear 6 being in the lower left slot, gear 7 being in the upper middle, gear 8 lower middle, gear 9 upper right and then gear 10 in lower right. The Eaton Fuller 10 speed is one of the easier transmissions to drive in the game.
Eaton Fuller 13 Speed Transmission
We can see by the schematic that, again, like the Eaton Fuller 10 speed our Reverse gears aren't split. They are a high range and a low range. We can also see that the gears L - 4 in the low aren't split, low gear starts in the lower left position, gear 1 is in the upper middle, gear 2 is in the lower middle, gear 3 is in the upper right and gear 4 is in the lower right.
Going into the high range we can see our gears are now going to start being split into high and low. 5L/5H being in the upper middle, 6L/6H being in the lower middle, 7L/7H being in the upper right and 8L/8H then being in the lower right.
Eaton Fuller 18 Speed Transmission
The Eaton Fuller 18 speed we can see is chock full of gears. We first off see in the upper left position we have a R1L and R1H in the low range and then a R2L and R2H in the high range. The lower left corner is where the Low, or granny as we call them in the US, gears are located. We have a LL and a LH. We then see that every gear in the other 4 shift positions are all split.
Gear 1L/1H starts in the upper middle, 2L/2H in the lower middle, 3L/3H in the upper right and then 4L/4H in the lower right.
Gear 5L/5H starts in the upper middle, 6L/6H in the lower middle, 7L/7H in the upper right, then finishing with 8L/8H being in the lower right position.
Volvo 12 Speed and 12+2 Speed
With the Volvo 12+2 we can start to see how most European shift patterns are set up. Most European shift patterns use only 5 of the 6 positions on an H-shifter. Although the positions they don't use differ most only use 5 of 6 positions.
Starting off in the top right in low range we can see gears C1 and C2, these are crawler gears. They are a very low gear ratio for either starting with massive weight or slick conditions and the like. We can also see in the lower left that we have 4 reverse gears. In the low range we have RLL and RLH, in the high range we have RHL and RHH.
For our low range gears we start with 1L/1H in the upper middle, 2L/2H in the middle, 3L/3H in the upper right and then we can see there is no gear in the lower right.
For our high range we start with 4L/4H in the upper middle, 5L/5H in the lower middle, 6L/6H in the upper right and once again no gear in the lower right.

The Volvo 12 speed transmission I'm not going to make an entire new section for or schematic. The changes are minor enough that I can just explain them. For one you only have 2 reverse gears and the other difference is there are no crawler gears in a Volvo 12 speed.
Scania 12 Speed and 12+2 Speed Transmissions
Starting off in the upper right of the Scania 12+2 we can see we have 2 reverse gears in the low range RL/RH, there is no high range reverse gears. In the lower right in low range we can see, like the Volvo, we have crawler gears C1/C2, there is no high range gear in the lower left.
Starting off in our low range we can see there is no gear in the upper middle position, 1L/1H is in the lower middle, 2L/2H is in the upper right and 3L/3H then in the lower right position.
In our high range we can see, once again, there is no gear in the upper middle, 4L/4H is in the lower middle, 5L/5H in the upper right and then 6L/6H finishing off in the lower right.

Like the Volvo I'm not going to make an entire new schematic or explanation on it's layout, the differences are minor. The only difference in a Scania 12 speed verses a Scania 12+2 is that there are no crawlers gears.
In the ZF 12 speed transmission we can see that we have no gear in the upper left position. We also see that in the lower left position we have one lonely, little reverse gear. It's not split and there is no high range.
In the low range we start in the upper middle with 1L/1H, lower middle position has no gear, 2L/2H are in the upper right position and then 3L/3H are in the lower right position.
In the high range we start with 4L/4H in the upper middle, again there is no gear in the lower middle position, 5L/5H are in the upper right position and 6L/6H finish it off in the lower right position.
The Zf 16 speed looks much the same as the ZF 12 with the addition of another gear slot to add 4 more gears. Starting off at the upper left we can see, once again, there is no gear here. There is only one reverse again in the low range and no high range.
Starting off our low range forward gears we have 1L/1H in the upper middle position, 2L/2H in the lower middle position, 3L/3H in the upper right position and then 4L/4H in the lower right position.
In our high range we have 5L/5H in the upper middle position, 6L/6H in the lower middle position, 7L/7H in the upper right position and 8L/8H finishing it off in the lower right position.

Using the H-shifter gearbox


The H-shifter support is intended to be used with Logitech G27 and compatible wheels. It will not work with normal buttons!

The shifters that are part of common commercial racing wheels are designed to mimic the layout of the manual shifters in cars that usually have up to six gears for forward movement. The trucks on the other hand tend to have much more gears. Having separate position for each gear would be not practical so an additional control is used to select an active gear set. Then a single gear from the set is selected by standard H-shifter pattern. For more information about available patterns see Wikipedia.

The gearbox simulated in the game has twelve forward gears and one reverse gear. In the default configuration the in-game H-shifter gearbox behaves as a "Range transmission" (see link above) where the "Shifter Toggle 1" button switches between gear set 1-6 and gear set 7-12. (see Controller options in the game, on the G27 it is mapped to the leftmost red button on the H-shifter by default).

Gear shifting example

You have a gear 6 selected and you want to shift up to the gear 7 - you need to press the "Shifter Toggle 1" button to switch to gear set 7-12 and then move the H-shifter stick to the position 1.

In similar way, to shift down from gear 7 to gear 6, press the "Shifter Toggle 1" to switch to gear set 1-6 and move the H-shifter stick to the position 6.

Prepared layouts

The game provides three layouts which can be selected from the the Controllers in-game option screen using the "Shifter layout" option.

Range transmission

This is the default configuration used by the game. The "Shifter Toggle: 1" selects between gears set 1-6 and gear set 7-12.

Splitter transmission

The "Shifter Toggle: 1" selects between odd-numbered gears (1,3,5,7,9,11) and even-numbered (2,4,6,8,10,12) gears.

Range-Splitter transmission

This configuration tries to emulate a layout of a real Scania H-shifter. Note that the game does not simulate the second reverse gear nor the two crawling gears so corresponding positions are not used.

This case is a combination of both preceding transmission types where the "Shifter Toggle: 1" switches between gear ranges and "Shifter Toggle: 2" switches between splitted gears.

Advanced configuration

The default H-shifter layout was selected to fit the most players, however with some tweaking of the gearbox configuration file it is possible to create a different layouts.

The gearbox configuration files for individual predefined layouts can be found in your profile directory (remember to replace the PROFILE_ID with your real profile identifier):

My Documents\Euro Truck Simulator 2\profile\PROFILE_ID\gearbox*.sii

The files contain a list of entries that map the condition triplet (h shifter position, selector 1 state, selector 2 state) to the concrete gear to use.

direct_gearbox_gear : _nameless.0F5B.B220 { gear_impulse_index: 0 selector_1: -1 selector_2: -1 gear: 0 }

Defines which position should the H-shifter be in:

  • 0 - neutral
  • 1 - "Shifter Position: Reverse"
  • 2 - "Shifter Position: 1"
  • 3 - "Shifter Position: 2"
  • ...
  • N - "Shifter Position: N"
Take care when editing the input configuration (see below). The game does not check if your H-shifter hardware supports the position you've entered.

Defines the state of the first selector:

  • -1 - ignore the selector state
  • 0 - the selector should be off
  • 1 - the selector should be on

Defines the state of the second selector.
See selector_1 for list of possible values.


The gear to shift in when the three conditions above are met.

Custom hardware

It is possible to use a custom H-shifter hardware provided that it reports the position as continuous press of some button. With more complex custom configuration of the input a position reported as axis value (e.g. aircraft throttle) can be also supported.

If the hardware has the ability to differentiate both positions of the range or splitter toggles, an additional inputs gearsel1on / gearsel2on and gearsel1off / gearsel2off, which are not accessible through the UI, can be configured instead of the toggling one.

Advanced input configuration

The game UI supports use of up to three controllers. The game itself is able to simultaneously use of more than three controllers, however such setup can not be configured through the game user interface and manual tweaking of the game's configuration files is required.

This section describes how an advanced user can manually tweak the configuration file to be able to use more than three controllers or create even more complex. By manual tweaking of the configuration it is possible to add some features not directly supported by the game UI such as

  • Use a flight yoke throttle instead of h-shifter.
  • Use a shift button selecting between two sets of functionalities assigned to other buttons for use with controllers which have limited number of buttons.
  • Use single button to toggle between various pages in the adviser.
  • Provide independent sensitivity for vertical and horizontal look control.
  • Use a TrackIR compatible head tracker to control movement of the truck for people with some disabilities.

Configuration file

The controller configuration is stored in profile directory (remember to replace the PROFILE_ID with your real profile identifier):

My Documents\Euro Truck Simulator 2\profile\PROFILE_ID\controls.sii

The file gets created when the controller or keyboard option screen is opened for the first time and contains a set of configuration lines which describe various components of the configuration.


This is an example how to use accelerator and brake pedal from a secondary controller and a horn button from a third controller without using the in-game UI. The same mechanism can be used if more than three controllers should be used.

  1. Using the steps described in the Input identification section determine the identification of the accelerator input on the secondary controller.
    Example identification:
  2. Determine the identification of the brake pedal input on the secondary controller.
    Example identification:
  3. Determine the identification of the button input on the third device.
    Example identification:
  4. Restore the default configuration on both keyboard and controller options pages in the game (not strictly necessary, just for purpose of this example) and configure the primary device in a normal way using UI.
  5. To connect the accelerator pedal from the secondary controller to the in-game throttle input:
    Find the text in the configuration file and change the input identification so in our example it so it reads
  6. To connect the brake pedal from the secondary controller to the in-game brake input:
    Find the text in the configuration file and change the input identification to the secondary controller brake pedal identification so in our example it reads
  7. In this case the pedals are reported as two separate axes so you need to turn off the combined axis by changing the value in to
  8. Depending on the device you might want to configure the deadzone for those inputs by changing values in and
  9. To connect the button from the third controller to the in-game horn input:
    Find the text in the configuration file and change the input identification so in our example it reads

Input identification

The game identifies individual inputs on the controllers using a name composed from several parts in following format:


On Windows OS the SYSTEM_ID will be almost always set to di8 indicating that DirectInput8 is used.

The DEVICE_ID is a string identifying the specific controller device. There are two ways to determine identification of the desired device. You can select the device as active in the UI and check what the game has stored in the device alias (find line containing text ) in configuration file. Alternatively you can look inside the game.log file for lines with following format:

[di8] Initializing device 'DEVICE_NAME' as 'DEVICE_ID'

The corresponding identification to use in the configuration file is then di8.'DEVICE_ID'

The INPUT_ID identifies a concrete input (e.g. axis, button) on the device. The best way to determine it is to use the game UI to create binding using that input and to check what the game has stored in the configuration file. For controllers it is usually b1 - b128 for buttons, x, y, z, rx, ry, rz for axes, sl1 or sl2 for sliders and pov_(1|2|3|4)_(up|down|left|right) for POVs

Sometimes the input identification is followed by an additional specification of the component of the input (e.g. which represents X component of the mouse position delta). At other times a defined alias might be used to shorten part of the input name.

Component types

Device alias

Example format: device joy `di8.'{A76B60D0-A8FD-11E1-8002-444553540000}|{C29B046D-0000-0000-0000-504944564944}'`

User-creatable: Yes

The device alias defines a new name ("joy") which can be used in other parts of the configuration file as a shortcut to reference a specific input device without having to always use its full identification. Defining and using the device alias also allows simple switch to a different compatible device by changing the alias target without having to update the rest of the configuration. By default the game creates three aliases keyboard, mouse and joy to identify keyboard, mouse and joystick device selected in the UI.

Input alias

Example format: input j_steer `joy.x`

User-creatable: Yes

The input alias defines a new name ("j_steer") which can be used in other parts of the configuration file as a shortcut to reference a specific input (axis, button) from input device without having to specify the longer name. Same as with the device aliases case, input aliases also allow easy configuration changes. The game axis configuration UI works by changing input aliases to point to the selected axes.


Example format: constant c_steer_dz 0.000000

User-creatable: Yes

The constant defines a named ("c_steer_dz") numeric value which might be used by calculations in other parts of the configuration file or directly by the game itself (e.g. FF strength).


Example format: mix dsteerleft `keyboard.larrow?0 | keyboard.a?0`

User-creatable: No

The mix defines an expression which is used to calculate value of a single game input. The game can use this value as an analog input (e.g. fraction of the rotation of the steering wheel) or as a logical value (e.g. wipers toggle).

The interpretation and additional configuration of the individual mixes (in what situations they are evaluated) is hardcoded in the game and it is currently not possible to create additional mixes in the configuration file.

In the simplest form the expression returns value of a single input. The more complex forms can use several mathematical and logical functions (see below) to derive the results from more than one input. Note that the UI input configuration screens directly supports only a very limited subset of the expressions and will display "Complex" message if they can not handle the expression.

Generally there are two types of mix evaluation.

  • Event based - this mix evaluates whenever there is change in any input (or other mix) it depends on. Mixes which read to individual presses (e.g. gear change, any_cmd) are usually of this type. As of 1.3.1. those mixes get duplicate evaluations whenever they react to button which generates characters (e.g. character key in keyboard). While usually not issue, this might be important when using the mix in loopback mode (e.g. it references old value of itself).
  • Frame based - this mix evaluates at end of the frame. Mixes which react to hold (e.g. horn) or provide analog values (e.g. steering) are usually of this type.

User-created components

For some component types it is possible to create additional components simply by using additional component definition line in the configuration file. Names of such components must meet following requirements:

  • Must be unique within the configuration file.
  • Must have at most 12 characters.
  • Only alphanumeric characters and underscore character are allowed.


The expressions are used to combine device inputs and apply deadzones or a non-linear functions to them. Several types of values can be used in the expression:

  • A reference to a constant value (e.g. 2.0)
  • A reference to a named constant (e.g. c_steer_dz).
  • A reference to a controller inputs using its full (e.g. or aliased form (e.g. In cases of some special inputs an additional component selector (.x, .y, .z, .yaw, .pitch, .roll) might be needed. In the default configuration file you will see that alternative syntax is used. That syntax indicates that if the input can not be found, the sub-expression should behave as if a constant 0 was returned from the device instead of reporting error and failing entire expression.
  • A reference to some other mix (e.g. dforward). Note that circular references are not allowed, however it is possible to reference the mix this expression belongs to. In that case a previous value is returned. Note that there are no guarantees on frequency or time between calls however it might be used to implement simple counters or toggles when used with the event-based mixes.
  • A special name unbound which resolves to constant zero. It is used to preserve information if no key is assigned to the primary binding slot.

The values can be combined using arithmetical (+, -, *, /) and logical (&, |, !) operators. Note that operator precedence rules are very simple so use of the brackets is highly recommended. When a value is interpreted in a logical context (e.g. during logical OR or AND operations or when it is used as logical value by the game), values greater than or equal to 0.5 evaluate to true and other values evaluate to false. Logical operators return 1.0 for true and 0.0 for false and have a short-circuit evaluation.

Following set of functions is also available. The range in brackets indicate allowed number of parameters to the function:

max(1..)Returns biggest from the parameters.
min(1..)Returns smallest from the parameters.
abs(1)Absolute value of the parameter.
sign(1)Returns -1 if parameter is negative number, 1 if the parameter is positive number and 0 for zero.
gt(2)Returns 1.0 if the first parameter is greater than the second one.
gte(2)Returns 1.0 if the first parameter is greater than or equal to the second one.
lt(2)Returns 1.0 if the first parameter is lower than the second one.
lte(2)Returns 1.0 if the first parameter is lower than or equal to the second one.
sel(3)Returns the second parameter if the first parameter evaluates to true (see above), for false returns the third parameter.
bool(1)Returns 1.0 if the first parameter evaluates to true (see above) and zero otherwise.
normalize(2-3)Returns normalized position of the first parameter in the range formed by <second parameter, third parameter>. If the value is outside of the range, it will be clamped to it. If third parameter is not provided, 1.0 will be used. If the second and third parameter do not form valid non-empty range, zero will be returned.
deadzone(2-3)Applies a zero-symmetrical deadzone. Similar to the normalize, however it applies symmetrically to the negative values as well. If the second parameter is negative, it is set to zero.
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Semi-trailer truck

Combination of a tractor unit and one or more semi-trailers to carry freight

Not to be confused with Semi-trailer.

"18 wheeler" and "Eighteen wheeler" redirect here. For other uses, see 18 wheeler (disambiguation).

"Truck and trailer" redirects here. For use of the expression in rugby union, see Glossary of rugby union terms § T.

"Big Rig" redirects here. For other uses, see Big Rig (disambiguation).

"Big rigs" redirects here. For the 2003 video game, see Big Rigs: Over the Road Racing.

Tractor with a end-dump trailer
An FAWsemi-trailer truck in China

A semi-tractor-trailer truck, also known as simply a semi-trailer truck, semi-tractor truck, semi-tractor-trailer or tractor-trailer truck, is the combination of a tractor unit and one or more semi-trailers to carry freight. A semi-trailer attaches to the tractor with a type of hitch called a fifth-wheel.

It is variously known as a transport truck, semi-truck, trailer truck, tractor truck, transfer truck, articulated truck, articulated lorry (UK), artic, single truck, semi-trailer, tractor-trailer, semi-tractor, semi, trailer, tractor, big rig, eighteen-wheeler, juggernaut, depending on the country and region.

Regional configurations[edit]


The noticeable difference between tractor units in Europe and North America is that almost all European models are cab over engine (called "forward control" in the UK[1]), while the majority of North American trucks are "conventional" (called "normal control" or "bonneted" in the UK[2]).[3] European trucks, whether straight trucks or fully articulated, have a sheer face on the front. This allows shorter trucks with longer trailers (with larger freight capacity) within the legal maximum total length. Furthermore, it offers greater maneuverability in confined areas, a more balanced weight-distribution and better overall view for the driver. The major disadvantage is that for repairs on COE trucks, the entire cab has to hinge forward to allow maintenance access. Conversely, "conventional" cab tractors offer the driver a more comfortable driving environment, easier access getting in or out and better protection in a collision.[citation needed]

In Europe, usually only the driven tractor axle has dual wheels, while single wheels are used for every other axle on the tractor and the trailer. The most common combination used in Europe is a semi tractor with two axles, and a cargo trailer with three axles, one of which is sometimes a lift axle, giving 5 axles and 12 wheels in total. This format is now common across Europe as it is able to meet the EU maximum weight limit of 40,000 kg (88,000 pounds) without overloading any axle. Individual countries have raised their own weight limit, for example the UK which has a 44,000 kg (97,000 pounds) limit, this increase is achieved by adding an extra axle to the tractor usually in the form of a middle unpowered lifting axle (midlift) with a total of 14 wheels. The lift axles used on both tractors and trailers allow the trucks to remain legal when fully loaded (as weight per axle remains within the legal limits); on the other hand, these axle set(s) can be raised off the roadway for increased maneuverability, or for reduced fuel consumption and tyre wear when carrying lighter loads. Although lift axles usually operate automatically, they can be lowered manually even while carrying light loads, in order to remain within legal (safe) limits when, for example, navigating back-road bridges with severely restricted axle loads. For greater detail, see the United Kingdom section, below.

When using a dolly, which generally has to be equipped with lights and a license plate, rigid trucks can be used to pull semi-trailers. The dolly is equipped with a fifth wheel to which the trailer is coupled. Because the dolly attaches to a pintle hitch on the truck, maneuvering a trailer hooked to a dolly is different from maneuvering a fifth wheel trailer. Backing the vehicle requires same technique as backing an ordinary truck/full trailer combination, though the dolly/semi setup is probably longer, thus requiring more space for maneuvering. The tractor/semi-trailer configuration is rarely used on timber trucks, since these will use the two big advantages of having the weight of the load on the drive wheels, and the loader crane used to lift the logs from the ground can be mounted on the rear of the truck behind the load, allowing a short (lightweight) crane to reach both ends of the vehicle without uncoupling. Also, construction trucks are more often seen in a rigid + midaxle trailer configuration instead of the tractor/semi-trailer setup.

Continental Europe[edit]

All EuroCombi variants being considered for Europe-wide adoption

The maximum overall length in the EU and EEA member states was 18.75 m (61.5 ft) with a maximum weight of 40 or 44 tonnes (39.4 or 43.3 long tons; 44.1 or 48.5 short tons) if carrying an ISO container.[4] However, rules limiting the semi-trailers to 16.5 m (54 ft) and 18.75 m are met with trucks carrying a standardized 7.82 m (26 ft) body with one additional 7.82 m body on tow as a trailer.[5] 25.25-metre (83 ft) truck combinations were developed under the branding of EcoCombi which influenced the name of EuroCombi for an ongoing standardization effort where such truck combinations shall be legal to operate in all jurisdictions of the European Economic Area. With the 50% increase in cargo weight, the fuel efficiency increases with an average of 20% with a corresponding relative decrease in carbon emissions and with the added benefit of one third fewer trucks on the road.[4] The 1996 EU regulation defines a Europe Module System (EMS) as it was implemented in Sweden. The wording of EMS combinations and EuroCombi are now used interchangeably to point to truck combinations as specified in the EU document; however, apart from Sweden and Finland, the EuroCombi is only allowed to operate on specific roads in other EU member states. Since 1996, when Sweden and Finland formally won a final exemption from the European Economic Area rules with 60 tonne and 25.25-metre (83 ft) combinations, all other From 2006, 25.25 m truck trailer combinations are to be allowed on restricted routes within Germany, following a similar (on-going) trial in The Netherlands. Similarly, Denmark has allowed 25.25 m combinations on select routes. These vehicles will run a 60-tonne (59.1-long-ton; 66.1-short-ton) weight limit. Two types are to be used: 1) a 26-tonne truck pulling a dolly and semi-trailer, or 2) an articulated tractor unit pulling a B-double, member states gained the ability to adopt the same rules. In Italy the maximum permitted weight (unless exceptional transport is authorized) is 44 tonnes for any kind of combination with five axles or more. Czechia has allowed 25.25 m combinations with a permission for a selected route.

The tractor/semi-trailer configuration is rarely used on timber trucks, since these will use the two big advantages of having the weight of the load on the drive wheels, and the loader crane used to lift the logs from the ground can be mounted on the rear of the truck behind the load, allowing a short (lightweight) crane to reach both ends of the vehicle without uncoupling. Also construction trucks are more often seen in a rigid + midaxle trailer configuration instead of the tractor/semi-trailer setup.

Nordic Countries[edit]

A truck with a swap bodypulling a trailer using a dolly; the overall length is 25.25 m (83 ft)

Denmark and Norway allow 25.25 m (83 ft) trucks (Denmark from 2008, and Norway from 2008 on selected routes). In Sweden the allowed length has been 24 m (79 ft) since 1967. Before that, the maximum length was unlimited; the only limitations were on axle load. What stopped Sweden from adopting the same rules as the rest of Europe, when securing road safety, was the national importance of a competitive forestry industry.[4][6] Finland, with the same road safety issues and equally important forestry industry, followed suit. The change made trucks able to carry three stacks of cut-to-length logs instead of two, as it would be in a short combination. They have one on stack together with a crane on the 6×4 truck, and two additional stacks on a four axle trailer. The allowed gross weight in both countries is up to 60 t (59 long tons; 66 short tons) depending on the distance between the first and last axle.

In the negotiations starting in the late 1980s preceding Sweden and Finland's entries to the European Economic Area and later the European Union, they insisted on exemptions from the EU rules citing environmental concerns and the transportation needs of the logging industry. In 1995, after their entry to the union, the rules changed again, this time to allow trucks carrying a standard CEN unit of 7.82 m (26 ft) to draw a 13.6 m (45 ft) standard semi-trailer on a dolly, a total overall length of 25.25 m. Later, B-double combinations came into use, often with one 6 m (20 ft) container on the B-link and a 12 m (40 ft) container (or two 6 m containers) on a semi-trailer bed. In allowing the longer truck combinations, what would take two 16.5 m (54 ft) semi-trailer trucks and one 18.75 m (62 ft) truck and trailer to haul on the continent now could be handled by just two 25.25 m trucks – greatly reducing overall costs and emissions. Prepared since late 2012 and effective on January 2013, Finland has changed its regulations to allow total maximum legal weight of a combination to be 76 t (75 long tons; 84 short tons). At the same time the maximum allowed height would be increased by 20 cm (8 in); from current maximum of 4.2 m (13.8 ft) to 4.4 m (14.4 ft). The effect this major maximum weight increase would cause to the roads and bridges in Finland over time is strongly debated.

However, longer and heavier combinations are regularly seen on public roads; special permits are issued for special cargo. The mining company Boliden AB have a standing special permit for 76-tonne (75-long-ton; 84-short-ton) combinations on select routes between mines in the inland and the processing plant in Boliden, taking a 50-tonne (49-long-ton; 55-short-ton) load of ore. Volvo has a special permit for a 32 m (105 ft), steering B-trailer-trailer combination carrying two 12 m (40 ft) containers to and from Gothenburg harbour and the Volvo Trucks factory, all on the island of Hisingen.[7] Another example is the ongoing project En Trave Till (lit. One more pile/stack) started in December 2008. It will allow even longer vehicles to further rationalize the logging transports. As the name of the project points out, it will be able to carry four stacks of timber, instead of the usual three. The test is limited to Norrbotten county and the European route E4 between the timber terminal in Överkalix and the sawmill in Munksund (outside Piteå). The vehicle is a 30 m (98 ft) long truck trailer combination with a gross weight exceeding 90 tonnes (89 long tons; 99 short tons). It is estimated that this will give a 20% lower cost and 20-25% CO2 emissions reduction compared to the regular 60-tonne (59-long-ton; 66-short-ton) truck combinations. As the combinations spreads its weight over more axles, braking distance, road wear and traffic safety is believed to be either the same or improved with the 90-tonne (89-long-ton; 99-short-ton) truck-trailer. In the same program two types of 76-tonne (75-long-ton; 84-short-ton) combinations will be tested in Dalsland and Bohuslän counties in western Sweden: an enhanced truck and trailer combination for use in the forest and a b-double for plain highway transportation to the mill in Skoghall. In 2012, the Northland Mining company received permission for 90-tonne (89-long-ton; 99-short-ton) combinations with normal axle load (an extra dolly) for use on the 150 km (93 mi) Kaunisvaara-Svappavaara route, carrying iron ore.[8][9][10]

As of 2015[update], the longest and heaviest truck in everyday use in Finland is operated by transport company Ketosen Kuljetus as part of a pilot project studying transport efficiency in the timber industry. The combined vehicle is 33 metres (108 ft) long, has 13 axles, and weighs a total of 104 tonnes (102 long tons; 115 short tons).[11][12]

Starting from Jan 21 2019 Finland Government change the maximum allowed length of truck from 25.25 to 34.50 meters (82.8 to 113.2 ft). New types of vehicle combinations that differ from the current standards may also be used on the road. The requirements for combinations also include camera systems for side visibility, an advanced emergency braking and lane detector system, electronic driving stability system and electronically controlled brakes. [1][2]

United Kingdom[edit]

In the United Kingdom the maximum permitted gross weight of a semi-trailer truck without the use of a Special Type General Order (STGO) is 44,000 kg (97,000 lb). In order for a 44,000 kg semi-trailer truck to be permitted on UK roads the tractor and semi-trailer must have three or more axles each. Lower weight semi-trailer trucks can mean some tractors and trailer having fewer axles.[13] In practice, as with double decker buses and coaches in the UK, there is no legal height limit for semi-trailer trucks; however, bridges over 16.5 ft (5.03 m) do not have the height marked on them. Semi-trailer trucks in continental Europe have a height limit of 13.1 ft (4.0 m). Vehicles heavier than 44,000 kg are permitted on UK roads but are indivisible loads, which would be classed as abnormal (or oversize). Such vehicles are required to display an STGO (Special Types General Order) plate on the front of the tractor unit and, under certain circumstances, are required to travel by an authorized route and have an escort.

Most UK trailers are 45 ft (13.7 m) long and, dependent on the position of the fifth wheel and kingpin, a coupled tractor unit and trailer will have a combined length of between 50 and 55 ft (15.25 and 16.75 m). Although the Construction and Use Regulations allow a maximum rigid length of 60 ft (18.2 m), this, combined with a shallow kingpin and fifth wheel set close to the rear of the tractor unit, can give an overall length of around 75 ft (22.75 m).[14]

Starting in January 2012 the Department for Transport is conducting a trial of longer semi-trailers. The trial involves 900 semi-trailers of 48 ft (14.6 m) in length (i.e. 3 ft [1 m] longer than the current maximum), and a further 900 semi-trailers of 51 ft (15.65 m) in length (i.e. 7 ft [2.05 m] longer). This will result in the total maximum length of the semi-trailer truck being 57 ft (17.5 m) for trailers 48 ft in length, and 61 ft (18.55 m) for trailers 51 ft long. The increase in length will not result in the 97,000 lb weight limit being exceeded and will allow some operators to approach the weight limit which may not have been previously possible due to the previous length of trailers. The trial will run for a maximum of 10 years. Providing certain requirements are fulfilled, a Special Types General Order (STGO) allows for vehicles of any size or weight to travel on UK roads. However, in practice any such vehicle has to travel by a route authorized by the Department of Transport and move under escort. The escort of abnormal loads in the UK is now predominantly carried out by private companies, but extremely large or heavy loads that require road closures must still be escorted by the police.

In the UK, some semi-trailer trucks have eight tires on three axles on the tractor; these are known as six-wheelers or "six leggers", with either the center or rear axle having single wheels which normally steer as well as the front axle and can be raised when not needed (i.e. when unloaded or only a light load is being carried; an arrangement known as a TAG axle when it is the rear axle, or mid-lift when it is the center axle). Some trailers have two axles which have twin tires on each axle; other trailers have three axles, of which one axle can be a lift axle which has super-single wheels. In the UK, two wheels bolted to the same hub are classed as a single wheel, therefore a standard six-axle articulated truck is considered to have twelve wheels, even though it has twenty tires. The UK also allows semi-trailer truck which have six tires on two axles; these are known as four-wheelers.

In 2009, the operator Denby Transport designed and built a 83 ft long (25.25 m) B-Train (or B-Double) semi-trailer truck called the Denby Eco-Link to show the benefits of such a vehicle, which were a reduction in road accidents and result in fewer road deaths, a reduction in emissions due to the one tractor unit still being used and no further highway investment being required. Furthermore, Denby Transport asserted that two Eco-Links would replace three standard semi-trailer trucks while, if limited to the current UK weight limit of 97,000 lb, it was claimed the Eco-Link would reduce carbon emissions by 16% and could still halve the number of trips needed for the same amount of cargo carried in conventional semi-trailer trucks. This is based on the fact that for light but bulky goods such as toilet paper, plastic bottles, cereals and aluminum cans, conventional semi-trailer trucks run out of cargo space before they reach the weight limit. At 97,000 lb, as opposed to 132,000 lb usually associated with B-Trains, the Eco-Link also exerts less weight per axle on the road compared to the standard six-axle 97,000 lb semi-trailer truck.

The vehicle was built after Denby Transport believed they had found a legal-loophole in the present UK law to allow the Eco-Link to be used on the public roads. The relevant legislation concerned the 1986 Road Vehicles Construction and Use Regulations. The 1986 regulations state that "certain vehicles" may be permitted to draw more than one trailer and can be up to 85 ft (25.9 m).[citation needed] The point of law reportedly hinged on the definition of a "towing implement", with Denby prepared to argue that the second trailer on the Eco-Link was one. The Department for Transport were of the opinion that this refers to recovering a vehicle after an accident or breakdown, but the regulation does not explicitly state this.

During BTAC performance testing the Eco-Link was given an "excellent" rating for its performance in maneuverability, productivity, safety and emissions tests, superseding ordinary semi-trailer trucks in many respects. Reportedly, private trials had also shown the Denby vehicle had a 20% shorter stopping distance than conventional semi-trailer trucks of the same weight, due to having extra axles. The active steer system meant that the Eco-Link had a turning circle of 41 ft (12.5 m), the same as a conventional semi-trailer truck.

Although the Department for Transport advised that the Eco-Link was not permissible on public roads, Denby Transport gave the Police prior warning of the timing and route of the test drive on the public highway, as well as outlining their position in writing to the Eastern Traffic Area Office. On 1 December 2009 Denby Transport were preparing to drive the Eco-Link on public roads, but this was cut short because the Police pulled the semi-trailer truck over as it left the gates in order to test it for its legality "to investigate any... offenses which may be found". The Police said the vehicle was unlawful due to its length and Denby Transport was served with a notice by the Vehicle and Operator Services Agency (VOSA) inspector to remove the vehicle from the road for inspection. Having returned to the yard, Denby Transport was formally notified by Police and VOSA that the semi-trailer truck could not be used. Neither the Eco-Link, nor any other B-Train, have since been permitted on UK roads. However, this prompted the Department for Transport to undertake a desk study into semi-trailer trucks, which has resulted in the longer semi-trailer trial which commenced in 2012.

North America[edit]

Tractor unit hauling tractor units in Idaho

In North America, the combination vehicles made up of a powered semi-tractor and one or more semitrailers are known as "semis", "semitrailers",[15] "tractor-trailers", "big rigs", "semi-trucks", "eighteen-wheelers" or "semi-tractor-trailers".

The tractor unit typically has two or three axles; those built for hauling heavy-duty commercial-construction machinery may have as many as five, some often being lift axles.

The most common tractor-cab layout has a forward engine, one steering axle, and two drive axles. The fifth-wheel trailer coupling on most tractor trucks is movable fore and aft, to allow adjustment in the weight distribution over its rear axle(s).

Ubiquitous in Europe, but less common in North America since the 1990s, is the cabover engine configuration, where the driver sits next to, or over the engine. With changes in the US to the maximum length of the combined vehicle, the cabover was largely phased out of North American over-the-road (long-haul) service by 2007. Cabovers were difficult to service; for a long time the cab could not be lifted on its hinges to a full 90-degree forward tilt, severely limiting access to the front part of the engine.

As of 2016[update], a truck could cost US$100,000, while the diesel fuel cost could be $70,000 per year.[16] Trucks average from 4 to 8 miles per US gallon (59 to 29 L/100 km), with fuel economy standards requiring better than 7 miles per US gallon (34 L/100 km) efficiency by 2014.[17] Power requirements in standard conditions are 170 hp at 55 mph (89 km/h) or 280 hp at 70 mph (113 km/h), and somewhat different power usage in other conditions.[18]

STAA double pup 28.5-foot trailers

The cargo trailer usually has tandem axles at the rear, each of which has dual wheels, or eight tires on the trailer, four per axle. In the US it is common to refer to the number of wheel hubs, rather than the number of tires; an axle can have either single or dual tires with no legal difference.[19][20] The combination of eight tires on the trailer and ten tires on the tractor is what led to the monikereighteen wheeler, although this term is considered by some truckers to be a misnomer (the term "eighteen-wheeler" is a nickname for a five-axle over-the-road combination). Many trailers are equipped with movable tandem axles to allow adjusting the weight distribution.

To connect the second of a set of doubles to the first trailer, and to support the front half of the second trailer, a converter gear known as a "dolly" is used. This has one or two axles, a fifth-wheel coupling for the rear trailer, and a tongue with a ring-hitch coupling for the forward trailer. Individual states may further allow longer vehicles, known as "longer combination vehicles" (or LCVs), and may allow them to operate on roads other than Interstates.

Long combination vehicle types include:

  • Doubles (officially "STAA doubles", known colloquially as "a set of joints"): Two 28.5 ft (8.7 m) trailers.
  • B-Doubles: Twin 33 ft (10.1 m) trailers in B-double configuration (very common in Canada but rarely used in the United States).
  • Triples: Three 28.5 ft (8.7 m) trailers.
  • Turnpike Doubles: Two 48 ft (14.6 m) trailers.
  • Rocky Mountain Doubles: One 40 to 53 ft (12.2 to 16.2 m) trailer (though usually no more than 48 ft (14.6 m)) and one 28.5 ft (8.7 m) trailer (known as a "pup").
  • In Canada, a Turnpike Double is two 53 ft (16.2 m) trailers, and a Rocky Mountain Double is a 50 ft (15.2 m) trailer with a 24 ft (7.3 m) "pup".[21][22][23]

Future long combination vehicles under consideration and study for the US MAP-21 transportation bill are container doubles. These combinations are under study for potential recommendation in November 2014:

  • 40 ft (12 m) trailer Turnpike Doubles, 142,000 lb (64,000 kg) GVWR
  • 40 ft (12 m) and 20 ft (6.1 m) trailer Rocky Mountain Doubles, 144,000 lb (65,000 kg) GVWR
  • Double 20 ft (6.1 m) trailers.

The US federal government, which only regulates the Interstate Highway System, does not set maximum length requirements (except on auto and boat transporters), only minimums. Tractors can pull two or three trailers if the combination is legal in that state. Weight maximums are 20,000 lb (9,100 kg) on a single axle, 34,000 lb (15,000 kg) on a tandem, and 80,000 lb (36,000 kg) total for any vehicle or combination. There is a maximum width of 8.5 ft (2.6 m) and no maximum height.[24][25]

Roads other than the Interstates are regulated by the individual states, and laws vary widely. Maximum weight varies between 80,000 lb (36,000 kg) to 171,000 lb (78,000 kg), depending on the combination.[26] Most states restrict operation of larger tandem trailer setups such as triple units, turnpike doubles and Rocky-Mountain doubles. Reasons for limiting the legal trailer configurations include both safety concerns and the impracticality of designing and constructing roads that can accommodate the larger wheelbase of these vehicles and the larger minimum turning radii associated with them. In general, these configurations are restricted to the Interstates. Except for these units, double setups are not restricted to certain roads any more than a single setup. They are also not restricted by weather conditions or "difficulty of operation". The Canadian province of Ontario, however, does have weather-related operating restrictions for larger tandem trailer setups.[27]



Main article: Road transport in Australia

Australian road transport has a reputation for using very large trucks and road trains. This is reflected in the most popular configurations of trucks generally having dual drive axles and three axles on the trailers, with four tyres on each axle. This means that Australian single semi-trailer trucks will usually have 22 tyres, which is generally more than their counterparts in other countries. Super single tyres are sometimes used on tri-axle trailers. The suspension is designed with travel limiting, which will hold the rim off the road for one blown or deflated tyre for each side of the trailer, so a trailer can be driven at reduced speed to a safe place for repair. Super singles are also often used on the steer axle in Australia to allow greater loading over the steer axle. The increase in loading of steer tyres requires a permit.

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 lighter duty applications only one of the rear axles of the truck is driven, and the trailer may have only two axles. From July 2007, the Australian Federal and State Governments allowed the introduction of B-triple trucks on a specified network of roads.[28] B-Triples are set up differently from conventional road trains. The front of their first trailer is supported by the turntable on the prime mover. The second and third trailers are supported by turntables on the trailers in front of them. As a result, B-Triples are much more stable than road trains and handle exceptionally well. True road trains only operate in remote areas, regulated by each state or territory government.

In total, the maximum length that any articulated vehicle may be (without a special permit and escort) is 53.5 m (176 ft), its maximum load may be up to 164 tonnes gross, and may have up to four trailers. However, heavy restrictions apply to the areas where such a vehicle may travel in most states. In remote areas such as the Northern Territory great care must be taken when sharing the road with longer articulated vehicles that often travel during the daytime, especially four-trailer road trains.

Articulated trucks towing a single trailer or two trailers (commonly known as "short doubles") with a maximum overall length of 19 m (62 ft) are referred to as "General access heavy vehicles" and are permitted in all areas, including metropolitan. B-doubles are limited to a maximum total weight of 62.5 tonnes and overall length of 25 m (82 ft), or 26 m (85 ft) if they are fitted with approved FUPS (Front Underrun Protection System) devices. B-doubles may only operate on designated roads, which includes most highways and some major metropolitan roads. B-doubles are very common in all parts of Australia including state capitals and on major routes they outnumber single trailer configurations.

Maximum width of any vehicle is 2.5 m (8.2 ft) and a height of 4.3 m (14 ft). In the past few years, allowance has been made by several states to allow certain designs of heavy vehicles up to 4.6 m (15 ft) high but they are also restricted to designated routes. In effect, a 4.6 meter high B-double will have to follow two sets of rules: they may access only those roads that are permitted for B-doubles and for 4.6 meter high vehicles.

In Australia, both conventional prime movers and cabovers are common, however, cabovers are most often seen on B-doubles on the eastern seaboard where the reduction in total length allows the vehicle to pull longer trailers and thus more cargo than it would otherwise.

New Zealand[edit]

New Zealand legislation governing truck dimensions falls under the Vehicle Dimensions and Mass Rules, published by NZ Transport Agency.[29] New rules were introduced effective 1 February 2017,[30] which increased the maximum height, width and weight of loads and vehicles, to simplify regulations, increase the amount of freight carried by road, and to improve the range of vehicles and trailers available to transport operators.

Common combinations in New Zealand are a standard semi-trailer, a B-double, or a rigid towing vehicle pulling a trailer with a drawbar, with a maximum of nine axles. Standard maximum vehicle lengths for trailers with one axle set are:

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

Trailers with two axle sets can be 20 m (66 ft) long, including heavy rigid vehicles towing two trailers. Oversized loads require, at minimum, a permit, and may require one or more pilot vehicles.[31]

High-productivity motor vehicle (HPMV) permits are issued for vehicles exceeding 44 tonnes, or the above dimensions.[32] Trucks up to 62 tonnes were allowed, with an initial bridge strengthening programme costing $12.5m.[33]


Side view and underside view of a conventional 18-wheeler semi-trailer truck with an enclosed cargo space. The underside view shows the arrangement of the 18 tires (wheels). Shown in blue in the underside view are the axles, drive shaft, and differentials. The legend for labeled parts of the truck is as follows:
1. tractor unit
2. semi-trailer (detachable)
3. engine compartment
4. cabin
5. sleeper (not present in all trucks)
6. air dam (not present in all trucks)
7. fuel tanks
8. fifth wheel coupling
9. enclosed cargo space
10. landing gear - legs for when semi-trailer is detached
11. tandem axles

Types of trailers[edit]

Main article: Semi-trailer

There are many types of semi-trailers in use, designed to haul a wide range of products.

Coupling and uncoupling[edit]

The cargo trailer is, by means of a king pin, hooked to a horseshoe-shaped quick-release coupling device called a fifth wheel or a turntable hitch at the rear of the towing engine that allows easy hook up and release. The truck trailer cannot move by itself because it only has wheels at the rear end: it requires a forward axle, provided by the towing engine, to carry half the load weight. When braking hard at high speeds, the vehicle has a tendency to fold at the pivot point between the towing vehicle and the trailer. Such a truck accident is called a "trailer swing", although it is also commonly described as a "jackknife".[34]Jackknifing is a condition where the tractive unit swings round against the trailer, and not vice versa.


A pair of semi-trailer "Suzies" at the back of an Australian prime mover, red line for emergency/supply and blue for control

Semi trucks use air pressure, rather than hydraulic fluid, to actuate the brake. The use of air hoses allows for ease of coupling and uncoupling of trailers from the tractor unit. The most common failure is brake fade, usually caused when the drums or discs and the linings of the brakes overheat from excessive use.

The parking brake of the tractor unit and the emergency brake of the trailer are spring brakes that require air pressure in order to be released. They are applied when air pressure is released from the system, and disengaged when air pressure is supplied. This is a fail-safe design feature which ensures that if air pressure to either unit is lost, the vehicle will stop to a grinding halt, instead of continuing without brakes and becoming uncontrollable. The trailer controls are coupled to the tractor through two gladhand connectors, which provide air pressure, and an electrical cable, which provides power to the lights and any specialized features of the trailer.

Glad-hand connectors (also known as palm couplings) are air hose connectors, each of which has a flat engaging face and retaining tabs. The faces are placed together, and the units are rotated so that the tabs engage each other to hold the connectors together. This arrangement provides a secure connection but allows the couplers to break away without damaging the equipment if they are pulled, as may happen when the tractor and trailer are separated without first uncoupling the air lines. These connectors are similar in design to the ones used for a similar purpose between railroad cars. Two air lines typically connect to the trailer unit. An emergency or main air supply line pressurizes the trailer's air tank and disengages the emergency brake, and a second service line controls the brake application during normal operation.

In the UK, male/female quick release connectors (red line or emergency), have a female on the truck and male on the trailer, but a yellow line or service has a male on the truck and female on the trailer. This avoids coupling errors (causing no brakes) plus the connections will not come apart if pulled by accident. The three electrical lines will fit one way around a primary black, a secondary green, and an ABS lead, all of which are collectively known as suzies or suzie coils.

Another braking feature of semi-trucks is engine braking, which could be either a compression brake (usually shortened to Jake brake) or exhaust brake or combination of both. However, the use of compression brake alone produces a loud and distinctive noise, and to control noise pollution, some local municipalities have prohibited or restricted the use of engine brake systems inside their jurisdictions, particularly in residential areas. The advantage to using engine braking instead of conventional brakes is that a truck can descend a long grade without overheating its wheel brakes. Some vehicles can also be equipped with hydraulic or electric retarders which have an advantage of near silent operation.


Traditional manual transmissionshave 4-5 ratios on main shift and 3-4 on the auxiliary: pictured is a 5×3with five main ratios and three auxiliaries

Because of the wide variety of loads the semi may carry, they usually have a manual transmission to allow the driver to have as much control as possible. However, all truck manufacturers now offer automated manual transmissions (manual gearboxes with automated gear change), as well as conventional hydraulicautomatic transmissions.

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

A ten-speed manual transmission, for example, is controlled via a six-slot H-box pattern, similar to that in five-speed cars — five forward and one reverse gear. Gears six to ten (and high-speed reverse) are accessed by a Lo/High range splitter; gears one to five are Lo range; gears six to ten are High range using the same shift pattern. A Super-10 transmission, by contrast, has no range splitter; it uses alternating "stick and button" shifting (stick shifts 1-3-5-7-9, button shifts 2-4-6-8-10). The 13-, 15-, and 18-speed transmissions have the same basic shift pattern but include a splitter button to enable additional ratios found in each range. Some transmissions may have 12 speeds.

Another difference between semi-trucks and cars is the way the clutch is set up. On an automobile, the clutch pedal is depressed full stroke to the floor for every gear shift, to ensure the gearbox is disengaged from the engine. On a semi-truck with constant-mesh transmission (non-synchronized), such as by the Eaton Roadranger series, not only is double-clutching required, but a clutch brake is required as well. The clutch brake stops the rotation of the gears and allows the truck to be put into gear without grinding when stationary. The clutch is pressed to the floor only to allow a smooth engagement of low gears when starting from a full stop; when the truck is moving, the clutch pedal is pressed only far enough to break torque for gear changes.


An electrical connection is made between the tractor and the trailer through a cable often referred to as a pigtail. This cable is a bundle of wires in a single casing. Each wire controls one of the electrical circuits on the trailer, such as running lights, brake lights, turn signals, etc. A straight cable would break when the rig went around corners, so a coiled cable is used which retracts these coils when not under tension. It is these coils that cause the cable to look like a pigtail.

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

  • 2 rear lights (red)
  • 2 stop lights (red)
  • 2 turning lights; one for right and one for left, flashing (amber; red optional in North America. May be combined with a brake light in North America)
  • 2 marking lights behind if wider than certain specifications (red; plus a group of 3 red lights in the middle in North America)
  • 2 marking lights front if wider than the truck or wider than certain specifications (white; amber in North America)

Wheels and tires[edit]

Although dual wheels are the most common, use of two single, wider tires, known as super singles, on each axle is becoming popular among bulk cargo carriers and other weight-sensitive operators. With increased efforts to reduce greenhouse gas emissions, the use of the super-single tire is gaining popularity. There are several advantages to this configuration. The first of these is that super singles reduce fuel consumption. In 1999, tests on an oval track showed a 10% fuel savings when super singles were used. These savings are realized because less energy is wasted flexing fewer tire sidewalls. Second, the lighter overall tire weight allows a truck to be loaded with more freight. The third advantage is that the single wheel encloses less of the brake unit, which allows faster cooling and reduces brake fade.

One of the major disadvantages of the super singles is that they are currently not as widely available as a standard tire. In addition, if a tire should become deflated or be destroyed, there is not another tire attached to the same hub to maintain the dynamic stability of the vehicle, as would be the case with dual wheels. With dual wheels, the remaining tire may be overloaded, but it will typically allow the vehicle to be safely stopped or driven to a repair facility.

In Europe, super singles became popular when the allowed weight of semitrailer rigs was increased from 38 to 40 tonnes.[35] In this reform the trailer industry replaced two 10-tonne (22,000 lb) axles with dual wheels, with three 8-tonne (18,000 lb) axles on wide-base single wheels. The significantly lower axle weight on super singles must be considered when comparing road wear from single versus dual wheels. The majority of super singles sold in Europe have a width of 385 mm (15.2 in). The standard 385 tires have a legal load limit of 4,500 kg (9,900 lb). (Note that expensive, specially reinforced 385 tires approved for 5,000 kg (11,000 lb) do exist. Their market share is tiny, except for mounting on the steer axle.)

Skirted trailers[edit]

Main article: Trailer skirt

An innovation rapidly growing in popularity is the skirted trailer. The space between the road and the bottom of the trailer frame was traditionally left open until it was realized that the turbulent air swirling under the trailer is a major source of aerodynamic drag. Three split skirt concepts were verified by the United States Environmental Protection Agency (EPA) to provide fuel savings greater than 5%, and four split skirt concepts had EPA-verified fuel savings between 4% and 5%.[36]

Skirted trailers are often combined with Underrun Protection Systems (underride guards), greatly improving safety for passenger vehicles sharing the road.

Underride guard[edit]

Crash test of an underride guard at 30–40 km/h (19–25 mph); the truck platform at head height has been prevented from slicing through the windshield

Underride protection systems can be installed at the rear, front and sides of a truck and the rear and sides of a trailer. A Rear Underrun Protection System (RUPS) is a rigid assembly hanging down from trailer's chassis, which is intended to provide some protection for passenger cars which collide with the rear of the trailer. Public awareness of this safeguard was increased in the aftermath of the accident that killed actress Jayne Mansfield on 29 June 1967, when the car she was in hit the rear of a tractor-trailer, causing fatal head trauma. After her death, the NHTSA recommended requiring a rear underride guard, also known as a Mansfield bar, an ICC bar, or a DOT bumper.[37][38]

The bottom rear of the trailer is near head level for an adult seated in a car, and without the underride guard, the only protection for such an adult's head in a rear-end collision would be the car's windshield and A pillars. The front of the car goes under the platform of the trailer rather than making contact via the passenger car bumper, so the car's protective crush zone becomes irrelevant and air bags are ineffective in protecting the passengers. The underride guard provides a rigid area for the car to contact that is lower than the lip of the bonnet/hood, preventing the vehicle from squatting and running under the truck and ensuring that the vehicle's crush zones and engine block absorb the force of the collision.

In addition to rear underride guards, truck tractor cabs may be equipped with a Front Underrun Protection System (FUPS) at the front bumper of the truck, if the front end is not low enough for the bumper to provide the adequate protection on its own. The safest tractor-trailers are also equipped with side underride guards, also called Side Underrun Protection System (SUPS). These additional barriers prevent passenger cars from skidding underneath the trailer from the side, such as in an oblique or side collision, or if the trailer jackknifes across the road, and helps protect cyclists, pedestrians and other vulnerable road users.[39]

In Europe, side and rear underrun protection are mandated on all lorries and trailers with a gross weight of 3,500 kilograms (7,700 lb) or more.[40] Several US states and cities have adopted or are in the process of adopting truck side guards, including New York City, Philadelphia, and Washington DC. The NTSB has recommended that the National Highway Traffic Safety Administration (NHTSA) develop standards for side underride protection systems for trucks, and for newly manufactured trucks to be equipped with technology meeting the standards.[41]

In addition to safety benefits, these underride guards may improve fuel mileage by reducing air turbulence under the trailer at highway speeds. Another benefit of having a sturdy rear underride guard is that it may be secured to a loading dock with a hook to prevent "trailer creep", a movement of the trailer away from the dock, which opens up a dangerous gap during loading or unloading operations.[42]

Semi-truck manufacturers[edit]

Current semi-truck manufacturers include:


Canada and United States[edit]


Other locations[edit]

Driver's license[edit]

View of a truck's interior dashboard

A special driver's license is required to operate various commercial vehicles.


Truck drivers in Australia require an endorsed license. These endorsements are gained through training and experience. The minimum age to hold an endorsed license is 18 years, and/or must have held open (full) driver's license for minimum 12 months.

The following are the heavy vehicle license classes in Australia:

  • LR (Light Rigid) – Class LR covers a rigid vehicle with a GVM (gross vehicle mass) of more than 4.5 tonnes but not more than 8 tonnes. Any towed trailer must not weigh more than 9 tonnes GVM. Also includes vehicles with a GVM up to 8 tonnes which carry more than 12 adults including the driver and vehicles in Class C.
  • MR (Medium Rigid) – Class MR covers a rigid vehicle with two axles and a GVM of more than 8 tonnes. Any towed trailer must not weigh more than 9 tonnes GVM. Also includes vehicles in Class LR.
  • HR (Heavy Rigid) – Class HR covers a rigid vehicle with three or more axles and a GVM of more than 15 tonnes. Any towed trailer must not weigh more than 9 tonnes GVM. Also includes articulated buses and vehicles in Class MR.
  • HC (Heavy Combination) – Class HC covers heavy combination vehicles like a prime mover towing a semi-trailer, or rigid vehicles towing a trailer with a GVM of more than 9 tonnes. Also includes vehicles in Class HR.
  • MC (Multi Combination) – Class MC covers multi-combination vehicles like road trains and B-double vehicles. Also includes vehicles in Class HC.

In order to obtain an HC License the driver must have held an MR or HR license for at least 12 months. To upgrade to an MC License the driver must have held a HR or HC license for at least 12 months. From licenses MR and upward there is also a B Condition which may apply to the license if testing in a synchromesh or automatic transmission vehicle. The B Condition may be removed upon the driver proving the ability to drive a constant mesh transmission using the clutch. Constant mesh transmission refers to crash box transmissions, predominantly Road Ranger eighteen-speed transmissions in Australia.


Regulations vary by province. A license to operate a vehicle with air brakes is required (i.e., normally a Class I, II, or III commercial license with an "A" or "S" endorsement in provinces other than Ontario). In Ontario, a "Z" endorsement[44] is required to drive any vehicle using air brakes; in provinces other than Ontario, the "A" endorsement is for air brake operation only, and an "S" endorsement is for both operation and adjustment of air brakes. Anyone holding a valid Ontario driver's license (i.e., excluding a motorcycle license) with a "Z" endorsement can legally drive any air-brake-equipped truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicle) up to 11 tonnes, that includes one trailer weighing no more than 4.6 tonnes if the license falls under the following three classes: Class E (school bus—maximum 24-passenger capacity or ambulance), F (regular bus—maximum 24-passenger capacity or ambulance) or G (car, van, or small-truck).

A Class B (any school bus), C (any urban-transit-vehicle or highway-coach), or D (heavy trucks other than tractor-trailers) license enables its holder to drive any truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicle) greater than 11 tonnes, that includes one trailer weighing no more than 4.6 tonnes.[45] Anyone holding an Ontario Class A license (or its equivalent) can drive any truck-trailer combination with a registered- or actual-gross-vehicle-weight (i.e., including towing- and towed-vehicles) greater than 11 tonnes, that includes one or more trailers weighing more than 4.6 tonnes.


A category CE driving licence is required to drive a tractor-trailer in Europe. Category C (Γ in Greece) is required for vehicles over 7,500 kg (16,500 lb), while category E is for heavy trailers, which in the case of trucks and buses means any trailer over 750 kg (1,650 lb). Vehicles over 3,500 kg (7,700 lb)—which is the maximum limit of B license—but under 7,500 kg can be driven with a C1 license. Buses require a D (Δ in Greece) license. A bus that is registered for no more than 16 passengers, excluding the driver, can be driven with a D1 license.

New Zealand[edit]

See also: Driver licence in New Zealand

In New Zealand, drivers of heavy vehicles require specific licenses, termed as classes. A Class 1 license (car license) will allow the driving of any vehicle with Gross Laden Weight (GLW) or Gross Combination Weight (GCW) of 6,000 kg (13,000 lb) or less. For other types of vehicles the 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 of 3,500 kg (7,700 lb) or less, any combination vehicle with GCW 12,001 kg (26,458 lb) or less, any rigid vehicle of any weight with no more than two axles, or any Class 1 vehicle.
  • Class 3 – Medium Combination Vehicle: Any combination vehicle of GCW 25,001 kg (55,118 lb) or less, or any Class 2 vehicle.
  • Class 4 – Heavy Rigid Vehicle: Any rigid vehicle of any weight, any combination vehicle which consists of a heavy vehicle and a light trailer, or any vehicle of Class 1 or 2 (but not 3).
  • Class 5 – Heavy Combination Vehicle: Any combination vehicle of any weight, and any vehicle covered by previous classes.
  • Class 6 – Motorcycle.

Further information on the New Zealand licensing system for heavy vehicles can be found at the New Zealand Transport Agency.


Taiwanese sign prohibiting heavy trailers

The Road Traffic Security Rules (道路交通安全規則) require a combination vehicle driver license (Chinese: 聯結車駕駛執照) to drive a combination vehicle (Chinese: 聯結車). These rules define a combination vehicle as a motor vehicle towing a heavy trailer, i.e., a trailer with a gross weight of more than 750 kilograms (1,653 lb).

United States[edit]

Drivers of semi-trailer trucks generally require a Class A commercial driver's license (CDL) to operate any combination vehicles with a gross combination weight rating (or GCWR) in excess of 26,000 lb (11,800 kg) if the gross vehicle weight rating (GVWR) of the towed vehicle(s) is in excess of 10,000 lb (4,500 kg). Some states (such as North Dakota) provide exemptions for farmers, allowing non-commercial license holders to operate semis within a certain air-mile radius of their reporting location. State exemptions, however, are only applicable in intrastate commerce; stipulations of the Code of Federal Regulations (CFR) may be applied in interstate commerce. Also a person under the age of 21 cannot operate a commercial vehicle outside the state where the commercial license was issued. This restriction may also be mirrored by certain states in their intrastate regulations. A person must be at least 18 in order to be issued a commercial license.

In addition, endorsements are necessary for certain cargo and vehicle arrangements and types;

  • H – Hazardous Materials (HazMat or HM) – necessary if materials require HM placards.
  • N – Tankers – the driver is acquainted with the unique handling characteristics of liquids tankers.
  • X – Signifies Hazardous Materials and Tanker endorsements, combined.
  • T – Doubles & Triples – the licensee may pull more than one trailer.
  • P – Buses – Any Vehicle designed to transport 16 or more passengers (including the driver).
  • S – School Buses – Any school bus designed to transport 11 or more passengers (including the driver).
  • W – Tow Truck

Role in trade[edit]

Modern day semi-trailer trucks often operate as a part of a domestic or international transport infrastructure to support containerizedcargoshipment.

Various types of rail flat bed train cars are modified to hold the cargo trailer or container with wheels or without. This is called Intermodal or piggyback. The system allows the cargo to switch from highway to railway or vice versa with relative ease by using gantry cranes.

The large trailers pulled by a tractor unit come in many styles, lengths, and shapes. Some common types are: vans, reefers, flatbeds, sidelifts and tankers. These trailers may be refrigerated, heated, ventilated, or pressurized, depending on climate and cargo. Some trailers have movable wheel axles that can be adjusted by moving them on a track underneath the trailer body and securing them in place with large pins. The purpose of this is to help adjust weight distribution over the various axles, to comply with local laws.


See also: Trucking industry in popular culture (United States)


  • 1960s TV series Cannonball
  • NBC ran two popular TV series about truck drivers in the 1970s featuring actor Claude Akins in major roles:
  • The Highwayman (1987-1988), a semi-futuristic action-adventure series starring Sam Jones, featuring hi-tech, multi-function trucks.
  • Knight Rider, an American television show featured a semi-trailer truck called The Semi, operated by the Foundation for Law & Government (F.L.A.G.) as a mobile support facility for KITT. Also, in two episodes KITT faced off against an armored semi called Goliath.
  • The Transformers, a 1980s cartoon featuring tractor-trailers as the Autobots' leader Optimus Prime (Convoy in Japanese version), their second-in-command Ultra Magnus, and as the Stunticons' leader Motormaster. Optimus Prime returned in the 2007 film.
  • Trick My Truck, a CMT show features trucks getting 'tricked out' (heavily customized).
  • Ice Road Truckers, a History Channel show charts the lives of drivers who haul supplies to remote towns and work sites over frozen lakes that double as roads.
  • 18 Wheels of Justice, featuring Federal Agent Michael Cates (Lucky Vanous) as a crown witness for the mafia who goes undercover, when forced into it, to fight crime.
  • Eddie Stobart: Trucks & Trailers, a UK television show showing the trucking company Eddie Stobart and its drivers.
  • Highway Thru Hell, a Canadian reality TV show that follows the operations of Jamie Davis Motor Trucking, a heavy vehicle rescue and recovery towing company based in Hope, British Columbia.


  • Duel, Steven Spielberg's 1971 film, features a Peterbilt 281 tanker truck as the villain
  • White Line Fever, a 1975 Columbia Pictures film, starring Jan-Michael Vincent
  • Smokey and the Bandit, a 1977 film featuring a number of trucks on the side of the bandit
  • Convoy, a 1978 film directed by Sam Peckinpah, starring Kris Kristofferson
  • Maximum Overdrive, Stephen King's 1986 film, featured big rigs as its primary homicidal villains
  • Over the Top (1987 film), a 1987 film directed by Menahem Golan, starring Sylvester Stallone
  • Black Dog, a 1998 film directed by Kevin Hooks, starring Patrick Swayze
  • Primemover, a 2008 film directed by David Caesar
  • Joy Ride, a 2001 film directed by John Dahl, starring Paul Walker and Steve Zahn
  • Big Rig, a 2008 documentary film directed by Doug Pray


  • "Convoy", a pop song by C. W. McCall, spurred sales of CB radios with an imaginary trucking story.
  • The eighteen-wheeled truck was immortalized in numerous country music songs, such as the Red Sovine titles "Giddyup Go", "Teddy Bear" and "Phantom 309", and Dave Dudley's "Six Days on the Road".
  • The thrash metal band, BigRig, was named after these trucks.
  • Country song "Eighteen Wheels and a Dozen Roses", made popular in 1987 by singer-songwriter Kathy Mattea.
  • "Roll On (Eighteen Wheeler)" by Alabama tells the story of a trucker who calls home to his family every night while out on the road.
  • "Papa Loved Mama" by Garth Brooks is about a trucker and his wife.
  • "Truck Drivin' Song" by "Weird Al" Yankovic tells the story of a female trucker, sung by a male with a deep voice.
  • "Cold Shoulder" by Garth Brooks is about a trucker stuck on the side of the highway during a blizzard, fantasizing about being home with his wife.
  • "Drivin' My Life Away" by Eddie Rabbitt, a former trucker, co-written with Even Stevens and David Malloy, sings of the life on the road.

Video games[edit]

See also: Category:Truck racing video games


See also[edit]


  1. ^Kilcarr, Sean (10 August 2017). "Getting cabover crazy". American Trucker. Retrieved 20 May 2018.
  2. ^Sutcliffe, Mike A. (Summer 2013). "The Sales & Service Literature of Leyland Motors Ltd"(PDF). Leyland Torque. The Leyland Society (60).
  3. ^Hjelm, Linus; Bergqvist, Björn (2009). "European Truck Aerodynamics – A Comparison Between Conventional and CoE Truck Aerodynamics and a Look into Future Trends and Possibilities". The Aerodynamics of Heavy Vehicles II: Trucks, Buses, and Trains. Lecture Notes in Applied and Computational Mechanics. 41. Springer. pp. 469–477. doi:10.1007/978-3-540-85070-0_45. ISBN .
  4. ^ abcRamberg, K. (October 2004). "Fewer Trucks Improve the Environment"(PDF). Svenskt Näringsliv.
  5. ^Wideberg, J.; et al. (May 2006). "Study Of Stability Measures And Legislation Of Heavy Articulated Vehicles In Different OECD Countries"(PDF). University of Seville, KTH and Scania.
  6. ^"Två regeringsbeslut för längre och tyngre fordon". Regeringskansliet. 16 April 2015. Retrieved 27 September 2015.
  7. ^"The next environmental improvement: Long truck rigs". Volvo Trucks. 3 October 2008.
  8. ^Krantz, Olivia (2014). "Where Size Matters". Uptime (2): 8–15.
  9. ^"Dispensation for 90 Tonnes Truckes is Favorable for All Concerned". 30 October 2012. Archived from the original on 28 January 2013.
  10. ^full law text in Finnish language, explanation by Finnish Forest Association in English, 76 tons in the newspaper
  11. ^Nilsson, Stefan (28 October 2015). "104-tons Scania i finskt försök". Trailer (in Finnish). Retrieved 10 September 2018.
  12. ^"Largest lorry in western Europe to start operating in Finnish Lapland". Finnish Forest Association. 26 August 2015. Retrieved 10 September 2018.
  13. ^"A Guide to Haulage & Courier Vehicle Types & Weights". Retrieved 28 July 2016.
  14. ^"Moving goods by road". HM (UK) Revenue & Customs. 5 April 2016. Retrieved 28 July 2016.
  15. ^Merriam-Webster
  16. ^Smith, Allen (25 May 2016). "What It Really Costs to Own a Commercial Truck". Ask The Trucker. Retrieved 18 May 2017.
  17. ^Dyer, Ezra. "10 Things You Didn't Know About Semi Trucks". Retrieved 25 March 2016.
  18. ^"Understanding Tractor-trailer Performance"(PDF). Caterpillar. 2006. p. 5. LEGT6380.
  19. ^"Guidelines on Maximum Weights and Dimensions"(PDF). Ireland Road Safety Authority. February 2013. Retrieved 26 June 2014.
  20. ^Crismon, Fred W (2001). US Military Wheeled Vehicles (3 ed.). Victory WWII Pub. p. 10. ISBN .
  21. ^British Columbia, max. dimension of semi-trailer truck
  22. ^Manitoba, max. dimension of semi-trailer truck
  23. ^Ontario, max. dimension of semi-trailer truck
  24. ^"Commercial Vehicle Size and Weight Program". Freight Management and Operations. US Department of Transportation. May 2003. FHWA-OP-03-099. Retrieved 7 August 2016.
  25. ^"Federal Size Regulations for Commercial Motor Vehicles". US Department of Transportation. Retrieved 2 October 2012.
  26. ^Jakubicek, Paul (16 January 2015). "Top 10 Heaviest Semi Trucks in the United States and Canada". Retrieved 12 July 2016.
  27. ^"Archived copy". Archived from the original on 17 May 2013. Retrieved 1 June 2013.CS1 maint: archived copy as title (link)
  28. ^"Vaile Announces the B-Triple Road Network" (Press release). Ministry for the Department of Infrastructure. 9 July 2007. Archived from the original on 2 June 2008.
  29. ^"Vehicle Dimensions and Mass Guide"(PDF). NZ Transport Agency.
  30. ^"Vehicle dimensions and mass (VDAM) changes".
  31. ^"Overdimension vehicles and loads"(PDF). NZ Transport Agency.
  32. ^"Land Transport Rule - Vehicle Dimensions and Mass 2016 - Rule 41001/2016"(PDF). NZTA. 1 May 2021.
  33. ^"More monster trucks to thunder along our roads". Stuff. 27 July 2013. Retrieved 4 May 2021.
  34. ^Rogers, Brian. "Truck Jackknife Accidents". Fried Rogers Goldberg. Fried Rogers Goldberg LLC. Retrieved 12 January 2017.
  35. ^"COST 334: Effects of Wide Single Tyres and Dual Tyres"(PDF). European Union. European Commission, Directorate General Transport. 29 November 2001.
  36. ^"EPA Smartway Verification of Trailer Undercarriage Advanced Aerodynamic Drag Reduction Technology". EPA Smartway. Retrieved 2 October 2012.
  37. ^"Underride Guard". Everything2. Retrieved 29 November 2007.
  38. ^United States Congressional Committee on Commerce (1997). Reauthorization of the National Highway Traffic Safety Administration. p. 39.
  39. ^"What does side underrun protection do on trucks and trailers".
  40. ^"Heavy goods vehicles". MOBILITY AND TRANSPORT, Road Safety. European Commission. Retrieved 2 November 2017.
  41. ^The National Law Review (17 August 2019). "U.S. Slow to Require Side Underride Guards on Trucks". Retrieved 20 September 2019.
  42. ^Underride Guard on Everything2; Retrieved: 29 November 2007.
  43. ^O'Dell, John (5 September 2019). "Here's Everything We Know About the Tesla Semi". Retrieved 10 April 2020.
  44. ^"Z" endorsementArchived 21 August 2007 at the Wayback Machine
  45. ^Ontario drivers classes
  46. ^"Official Rigs of Rods Forum". Rigs of Rods. Retrieved 18 August 2012.

External links[edit]

ETS2 - Manual vs Automatic Transmission Mode (Sequential vs Simple Automatic) Scania S Series 2016

CXN2615 wrote:The overall gear ratio is just the product of gearbox and differential (or if any, count in other reduction gears' ratio in the drive train)
No.1 has 1st in 39.4416 12th 2.64
No.2 has 1st in 36.1284 12th 2.4024

Basically, with same engine output, larger ratio number means more torque and less speed on wheel. Simplified to say, better acceleration (or climbing) but worse cruising fuel consumption.
But a too small final ratio could result that you can't use that final gear when cruising, no good for fuel consumption then.

You are right ... I made a simple test:
1) I set a cruise speed of 90 km/h ... with No.1 the gear , at that speed, was A12 near 1,000 rpm
2) With the same truck, with the same trailer weight, setting always a cruise speed of 90 km/h ... with No.2 the gear , at that speed, was A11 near 1,500 rpm (worst for fuel economy); in order to have the A12 and 1,000 rpm I needed 93 km/h.


Differences american truck simulator transmission

We discussed Wagner's "Ring of the Nibelungen" with her. Then they argued about the legends that revolved around Paganini. I cannot hide the fact that I was amazed at her education. But this is already superfluous. She looked at me very seriously.

SKRS Shifter Setup and Review (18 Speed Transmission for ATS/ETS2)

Or is experimenting with guys again. Be that as it may, now there is neither the desire nor the time to find out. Sisters, look here, something needs to be done with this, - Max slyly screwed up one eye. Anya silently turned on the vacuum cleaner and, as if she had not heard, was carefully brushing her brush across the carpet.

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