Talk:Semi-trailer truck

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I hope to soon write some pages from my 20 year experience as a (US) truck owner/operator. Some subjects would include: - maintainence and safety of tractor-trailers. - specification of componets (engines, transmitions, axles) when setting up a rig. - operating procedures for fair weather and foul. - size and weight laws in different locations. - loading and freight securement considerations for flatbed trailers. - Trucking in the extreme North end of N.America, and slightly beyond (on the oilfield ice roads)!

Feel free to comment: Tim Coahran, tcoahran@wsu.edu

Contents 1 Triple-trailers 2 European semi-trailer 3 Type of trailers 4 Article should be moved/renamed 5 Definition of semi-trailer 6 Authorized or vandalism? 7 What is this in english? 8 Would love stats! 9 Rename the article ? 10 About the Container King Sidepicker System In Canada-link 11 trial in germany 12 Trucking in Alaska 13 "Semi"? 14 Cab over the engine

[edit] Triple-trailers

On some interstate highways in the US, long-haul semi-trailer trucks can tow another full trailer at the end, which makes the vehicle look like a two-car small train. Some of the second cars are full trailers with wheels on both ends, while others are just regular semi-trailer cars hooked to the standard coupling device on another set of wheels in tow (sometimes referred to as a "dolly"). There are proposals to allow a third car to be added to the vehicle, but they face strong objections from some car drivers who share the highway with these longer trucks.

The above paragraph makes it sound like triple-trailers aren't actually in use. They are, and at one time were pretty common on I-84 in northern Oregon. This has decreased over time — and additional permits are required for it — due to safety concerns (I've also heard it suggested that trucking companies may have found it to not be as economical as they'd hoped, but I can't speak to the veracity of those claims; insurance costs, perhaps?). Anyone traveling through the Columbia River Gorge still stands a decent chance of seeing one, though. -- nknight 10:17, 10 May 2004 (UTC)

I've certainly seen them on the Ohio Turnpike. I half-jokingly refer to them as "death trains". I've edited the paragraph to clarify that these are in use on some highways. --Arteitle 07:18, Sep 1, 2004 (UTC)

---

I think triple trailers are common in Austrailia (I understand that these "road trains" have the right of way over smaller vehicles). Also, the picture seems not as clear as would be that of a typical 18 wheeler, especially with a full on side profile. Leonard G. 00:03, 13 May 2004 (UTC)

[edit] European semi-trailer

In Europe, most semi tractors have 2 axles, again with the front, steer, having two wheels, and rear, drive, having a pair of double wheels on each side. Thus, the most common configuration has 6 wheels. Conversely, the cargo trailer usually has three axles at the rear, each with dual wheels, or 12 wheels in total.

I am confused by this description of the European trailer. If I read the description right, in Europe, the tractor only has two axles, and the cargo end has 3 axles. That means the cargo container is sitting on 12 wheels on the rear end and 4 wheels (rear of the tractor) on the front end.

Yes. I wrote that after traveling through several European countries and paying attention to this - I've almost never seen tractor with three axles. Nikola

Here in Europe we usually don't have dual wheels under trailer. If trailer has 3 axles it usually means only 6 "super single" tyres. Tepo 25 September 2005

The weight of the tractor itself is distributed over the two front wheel and its own 4 wheels. ie. the middle 4 wheels are carrying both the load of the cargo and the engine. How does the weight distribution work? Assuming the weight of the cargo is distribute evenly on both ends, then the tire pressure on the road surface is quite lopsided. Since pressure = weight/area of road contact, the pressure these 4 wheels on the road surface is extremely high, theoretically 3 times those on the rear 12 wheels (1 axle supports the front end and 3 axles support the rear end of the cargo???). Probably strong enough to create a pot hole every couple of round trips. In the US, there are 8 wheels on each side of the cargo, hence the pressure and wear on the road surface is evenly distributed. Can someone in Europe explain the design philosophy behind such wheels arrangement? Does Europe trailers cause more road damage then their US counterpart?

I think that European trailers have their wheels moved more to the forward than American ones.

 ______\____USA_____
 o   oo          oo

 ______\____EU______
 o    o        ooo

but it should be checked with appropriate legislations really. Nikola 11:20, 23 Jul 2004 (UTC)

Picture above is just like trailer tyres are under trailer here in Europe. Trailers axle positions are what they are becouse of legislation which say a certain circle which tyres aren't allowed to cut when turning sharply. When carrying small and very heavy pallets you have to put more cargo over trailers axle and leave some empty space in front of them. On typical 3-axle trailer-bogie you can put 24 metric tons. 2 axle tractor-unit usually has CGW of 18 metric tons. Tepo 25 September 2005

Isn't it true that when wheels of the three closely spaced axles make a turn, they require some kind of differential to prevent squeaking? Each of these wheels probably turn at a different pivot point. When the wheels are move forward, there will be considerable fishtail swing out to the opposite side of the turn. The article also mention the lack of nose on the tractor. The different driver position, the swinging tail etc. will make driving a truck quite different in Europe. Does US truck driver need additional training before driving in Europe? Kowloonese 17:28, 23 Jul 2004 (UTC)

sep 25, 2005 In theory the difference between a nose or a no-nose truck would be like the differense from an ordinary car to a van... I've been in a Scania 112 with nose (though the nose would be less than half length of many US trucks) and I didn't have any problems. When you have a drivers license here, you're supposed to control any vehicle in that category.

If You move to Europe on a permanent basis, I think You need to take a local drivers license anyway, I assume a number of theory lessons to see what your level is before the test, and eventually a driving lesson to check out local rule differences. G®iffen 10:43, 25 September 2005 (UTC)

Input from Denmark: Usually in DK we have Tractor/semi (t/s) 2 axles/3axles for lighter cargo distribution and for anything that goes thru Switzerland (due to special weight limits, eco-points and who knows what else...)

For heavy goods and usually for things going north or east, t/s is 3/3.

In general (VERY general) the rule would be 8 tons to the front axle and 9 tons to each rear. (Somehow it adds up to a max legal total weight of... 24????? tons for a 3-ax vehicle - no clue why). Normally each axle on the semi carries 8 t, and the king pin takes "the rest" adding up to the tractors total. I don't know the english word for the "thing" that locks the kingpin (and trailer) to the tractor, but nevertheless, its common that this thing can be moved towards back or front to optimize weight transfer between tractors front and rear axles.

By the way, "modern" trailers often have single tires, ant often 3rd axle on the tractor also have singles. On some tractors and semis the rear axle is steering to save rubber on the tires, and to make a smaller turning circle. Also european semitrailers often have thir wheels more to the front than the american semis I've noticed. Of course, we also have more old cities with narrow roads, haven't we? G®iffen 20:06, 5 September 2005 (UTC)

In Sweden the axle weight limits are 10 metric tons (11.5 for a driving axle) for single axles, 19 for twin axles, and 24 for tripple axles. Vehicles with 2 axles are allowed to gross 18 metric tons, 3 axles 26 tons, and 4 or more axles 32 tons. The exception is trailers which are allowed to gross 36 metric tons if the axle distance is more than 7.2 meters. The most common combination here is truck-trailers, the truck with three axles and the trailer with four, grossing 60 metric tons with a length of 24 meters. There are also a fair amount of trucks with two trailers in a B-train configuration usually carrying shipping containers, one 20 ft and one 40 ft, which are allowed to be 25.25 meters. The same is true with trailers pulled by trucks using a dolly.

In Denmark "Søndagsavisen" from sep. 25, 2005 has an article on p.24 saying that the rules in DK "Are a lot closer to allowing 25,25m units of 60 tons in DK, starting with permission over Øresundsbron from Sweden to Kastrup Airport.

The Netherlands and Germany are testing at the moment, and Dansk Transport og Logistik (Transport organization) calculates 23-30 % savings on fuel by allowing (and of course using) the larger "module road trains" G®iffen 10:43, 25 September 2005 (UTC)

This is a typical (north)european tractor-semi combination, if you forget about the mid-axle trailer at the end. I assume 1. and 3. axle on the truck are steering axles, and this would be the only steering on the entire vehicle. G®iffen 20:04, 30 September 2005 (UTC)

I've never seen a tractor with a steerable rear axle, but it's common on 6x2 rigid trucks. The main advantage with it is a tighter turning radius, and less tire wear, but on a semi-trailer that doesn't matter much since they're mostly driven outside the cities. One of the trucks at work has a steerable rear axel and it definitely tightens the turns, but you've got to make sure there's nothing next to you when you start turning because the overhang can get pretty big.

In Denmark rear steering axles are quite common, both on trucks, semitrailers and buses. For some reason waste trucks often have steering on 2nd ax, while most other vehicles have it on 3rd.

For a test period buses are allowed with (somewhere around) 13,5 meters, if they have a steering 3rd axle. Normal max length for any vehicle is 12 m, except semis, which I think can be 13.6 m.

Another popular thing these years are so-called city-trailers, which means semitrailer with only one axle, where the steering makes it follow the track of the tractor. The system is also seen on 2-ax'd semis, with one or two steering axles.

Steering is normally shown in sales articles, i.e. Volvo 6*2/4 means volvo with 6 wheels, where 2 are drive wheels and 4 are steering. This system always count 2 wheels on one axle. If 6*2/2, usually you write 6*2. 6*6/6 wold probably be something armored from the military... G®iffen 16:44, 8 October 2005 (UTC)

I have been watching the roads, and yes, in Denmark I see a lot of 2-ax tractors with 3-ax semi. Those usually look like export trailers. Another large group is the 3/3 combination on the photo. This is also normal when driving 40 ft shipping containers.

[edit] Type of trailers

I am always curious what each kind of trailer is designed for. The cargo container trailer is obvious. But there are some trailers that shaped like a funnel with a nossle near the bottom. Some look like liquid containers and some look like for gravels or something solid. It would be nice to have pictures of each type of trailers here in the article.

Or perhaps in trailer. Nikola 11:20, 23 Jul 2004 (UTC)

• • On a similar note, it would be nice to explain how hazardous materials are moved using diferent kind of trailers. That has always intreged me. TomStar81 02:03, 7 Sep 2004 (UTC)

• Tank trailers for powder or liquid.
• Open or closed fladbeds for any cargo either solid or packed solid (ie. barrels, bales and pallets)
• (Word unknown, tip or dump trailers?) for gravel, dirt, waste, stones, grain, debree etc.
  • Dump trailer, sometimes known as an end-dump trailer as opposed to a belly-dump or hopper
• closed trailers with temperature control (freeze, cold or heat) for food and food products
  • Refer (more properly "refrigerated trailer")
• special trailers for animal transport
  • Livestock trailer
• (word unknown, pls insert) for heavy machines, macine parts, oversize loads
  • Low-boy
• trailers for shipping containers
• Different special constructions for specific types of cargo, e.g. automobile transport, timber etc.

G®iffen 16:57, 8 October 2005 (UTC)

• • I've interspersed my comments with yours. Also there's the Van trailer, which is the typical closed box trailer. Toiyabe 23:07, 19 April 2006 (UTC)

[edit] Article should be moved/renamed

I think this article should be named "Tractor-trailer". A semitrailer is a unit towed by a tractor and requies the fifth-wheel of the tractor to support the front. A full trailer, of course, is completely self-supporting, like a semitrailer/dolly combination. Rsduhamel 19:29, 6 Oct 2004 (UTC)

As far as I know, although tractor-trailer is the more correct term for a semi-trailer, most Australians and Americans would be unlikely to say "Tractor-Trailer" when referring to one. Any input from the rest of the world? --MartinRudat 09:07:56, 2005-08-30 (UTC)

I don't know about other places around the world, but in Australia, at least, if you were to say "Tractor-Trailer", the image that would come to mind would probably be a trailer pulled by a farm tractor. I only realised that "Tractor" is "Thing which applies Traction" rather than a farm implement after reading the article here on wikipedia. --MartinRudat 09:07:56, 2005-08-30 (UTC)

I had to read about a semi to know what it was, but I agree with MartinRudat about the farm tractor. Mainly because in Denmark the road tractor is called "trækker" - direct translation is "puller" as in pulling the trailer. By the way, semis are referred to as trailers in DK, while "your" trailers are called "påhængsvogne", translated something like "hook-on-waggons" because they are more or less fastened with a hook in the rear end. G®iffen 20:17, 5 September 2005 (UTC)

Well, I've heard the term "tractor-trailer" used among my coworkers quite frequently. But what do I know, I just used to drive them for a living. Rsduhamel 07:13, 5 May 2007 (UTC)

I think some or all of the information in the Construction section should be moved to the similar and more comprehensive Anatomy of a Truck section in Truck. Sticki 17:58, 20 September 2005 (UTC)

Article should definitely be renamed. As stated in the first paragraph, "a semi-trailer is a trailer without a front axle". The article then goes onto describe trailers (including front axles) and trailer (semi or otherwise) and locomotive combinations called variously articulated lorries, road-trains or otherwise. The semi-trailer is therefore a component of an articulated lorry - so either separate articles are required, or the article should be renamed. It makes more sense to name the article for the whole and then talk about the components, rather than - as at present - name the article for a component and then go onto to talk about other components and the whole. Anon.

:Since it is apparent from this thread and below's that both "semi-trailer truck" and "semi-trailer" have separate and specific meanings, and that the bulk of the current article should be under Semi-trailer truck, I have requested such a move. "Semi-trailer" specific text can then be extracted and returned to the freed-up Semi-trailer article space. ENeville 05:37, 9 September 2006 (UTC)

I would prefer an article name like Tractor-trailer truck (as a full name) over simply Tractor-trailer so as to make it clear we are talking about a type of truck, even though I understand most people in the business are too lazy to mention "truck" because the listeners in the business implicitly understand the talk is about trucks. Tractor-trailer could redirect to this this full name. Part of this problem is because there are many kinds of tractors and trailers, and tractor is hard to define exactly. I have no objection to the article staying at Semi-trailer truck. I do find the moniker "18-wheeler" to be an inaccurate name for all such trucks, because some do not have exactly 18 tires. I think 18-wheeler should be used for those that have 18 tires. H Padleckas 16:27, 8 July 2007 (UTC)

[edit] Definition of semi-trailer

This article didnt have a proper definition of a semi-trailer (apart from a vague etymology near the end) so I've replaced the etymology with a precise definition right at the begining where it aught to be so that anyone reading this article knows exactly what a semi-trailer is. It's worded as follows;-
"A semi-trailer is a trailer without a front axle. A large proportion of its weight is supported either by a tractor or by a detachable front axle assembly known as a dolly. A semi-trailer is equipped with legs to support it when it is uncoupled." Apgeraint 19:38, 12 April 2006 (UTC)

I agree that the title should be "Semi-trailer truck" instead of "Semi-trailer" because the latter refers only to the cargo segment while the former refers to the whole thing. If you want abbrev. probably "semi" suffices, but the article should have a more complete title. I actually am interested in an article that describes all the different kinds of semi-trailers found on the road. Some examples include the gasoline tanker, gravel loader, flat-bed for heavy equipment, cargo container, milk transporter, liquidifed gas tanker, timber hauler etc. Some photos to show how these trailers are used would be great. Kowloonese 01:46, 13 April 2006 (UTC)

May I suggest a gallery in the bottom? I'd like some different pics too, with "professional terms" describing the semitrailers G®iffen 12:51, 13 April 2006 (UTC)

I believe that the title of this article is absolutely correct This article is needed to define exactly what a semi-trailer is.
What is wrong with this article is that there are some elements in it not pertaining to semi-trailers. It would be better to put these in seperate articles.
There also seems to be a general lack of knowledge of the jargon (and of the exact meaning of some of the jargon). Since this is an encyclopedia, the correct terminology should be used and need to be defined as to their precise meaning. Maybe I'll sort this out when I get round to it. In the past 35 years I have trucked all round Europe and also travelled several times to the USA, Canada and Australia taking Photos of trucks and talking to truck drivers. One thing I have learned is that the jargon is exactly the same all over the English speaking world. It's only those unaquainted with the industry that use different words in different parts of the world since they don't know the correct terminology. Apgeraint 19:24, 13 April 2006 (UTC)

Please see Talk:Semi-trailer#Definition of Semi-trailer - comments please and provide feedback comments. H Padleckas 03:37, 13 July 2007 (UTC)

[edit] Authorized or vandalism?

Some ananymous user removed all about local differences. Is it vandalism, or did s/he put it somewhere else? I didn't like to rebuild it if there's a good explanation. G®iffen 14:53, 26 April 2006 (UTC)

Looking at the user's contributions, it doesn't look like the deleted information was put somwhere else. Seeing as the user is also Anon., I think that info should be put back. Toiyabe 15:19, 26 April 2006 (UTC)

[edit] What is this in english?

In danish, this is a blokvogn, but what do you call it? Is there an article about it, or is it just another semi? In da: I've started an article about it, and de: has one more or less about the heavy goods itself here - well, at least that's what my rusty german tells me. G®iffen 17:33, 13 July 2006 (UTC)

I've never seen a configuration like that in the US. Is that just a single tractor and a single trailer? If so it is officially a Class 10. If there's a dolly in there it would be a Class 13. Might be referred to as a "Permitted Vehicle" (i.e. it requires a special permit to operate as it will be overlength and/or overweight when loaded.)

Typically in the US you would see that sort of vehicle with one or more dollys up front, and maybe six split axles in the back (there's a picture of one at [1]. How does that thing turn? Do some of the axles on the trailer lift up (i.e. "tag axles"?)

Whenever larger than this, they usually have a lowered "middle" section and either

1. a dolly (rare in Denmark) or
2. a front end wheeled module

on the semi. But yes, technically this is a 5-axle tractor and 11 axle semi. Notice semiaxles 1,2,3,4 and 6 are airlifted. I believe that the driver can configure which semiaxle is "the not steering" and the others will track according to their position compared to the tractor and the locked axle. I don't remember if this had split axles (I assume that is "one axle in each side" instead of the same axle connecting both sides?)

The unit loads 240 metric tonnes plus the vehicle itself... Usually the total weight of any vehicle+trailer can never (legally) be more than 48 tonnes in DK.

Not to be commercial, but the company that owns the truck has an english homepage [2] with quite a few pics, showing their extremes. I didn't see any dolly-combinations. They like to use one brand of module trailers, that can be put together long, wide or in "blocks" of 2,3 or 4 axles extra according to the job.

I guess the banner in the bottom of this site illustrates "your" dolly combination?

Yeah, that's the sort of thing you usually see. Lift axles typically do not count towards the load rating in the US except on single-unit vehicles like concrete mixers and dump trucks. Toiyabe 18:32, 18 July 2006 (UTC)

Well, I find wisdom every day ;) Eh... Actually I just still need to know if there's a general term for overload vehicles in english? Above the shown one is called a class 10 or maybe class 13. I assume it is a (something) class 10 or 13, where "something" could be like heavy carriage, oversize vehicle or some other term covering all or most types of vehicles built for transporting items larger/heavier than the standard? As example the danish term blokvogn also includes mobile (wheeled) cranes over 32 tonnes and some other heavy or wide special vehic's. I did notice the term "permitted vehicle", but one can permit a lot of things for different occasions, right? G®iffen 14:58, 19 July 2006 (UTC)

I'm more familiar with the regulatory aspects. I've seen the terms "overweight", "oversize", "overdimensional" (covers oversize and overweight) and "permitted vehicle" (covers both oversize and overweight, maybe also some types of hazmats like nuclear waste). There's also the term "superheavy" which would refer to a vehicle that exceeds the bridge formula, and will require a specific load analysis for each bridge crossed. The regulatory terms vary slightly from state to state. There may well be a term used by truckers that is more specific to the vehicle itself, but I'm unaware of it.

Class 10 and Class 13 also include vehicles that are not oversize or overweight. A three axle tractor and three axle single trailer would fall into Class 10 (for instance a three axle dump truck and a three axle pup trailer). Rocky mountain and turnpike doubles would be class 13.

What's the translation of "blokvogn"? Big Wagon? Toiyabe 15:39, 19 July 2006 (UTC)

Blok is more or less the same as the english block (like a block of stone). Vogn is any unmotorized vehicle pulled by external engine or animal. It probably refers to carrying large rocks for building purposes (?) G®iffen 16:13, 19 July 2006 (UTC)

Well, last week I actually saw a dolly-setup for heavy load driving in Copenhagen. I think it was german or polish though.

Lately I've seen two or three danish solutions where an extra axle is mounted on the tractor unit. One I saw had the semi separated for loading from front end of trailer, and two hydraulic cylinders over this extra axle would help holding the "Swan neck" (what ever it's called in english) seems it's called a gooseneck in english - the coupling from the fifth wheel to the load area. I'd wonder how these cylinders act while driving - if they transfer load to the extra axle or if it's just for the trailer separation. G®iffen 21:48, 8 July 2007 (UTC)

[edit] Would love stats!

Hi! I came here looking for statistics on vehicle weight, cargo weight, and fuel efficiency. I was trying to calculate the cost and fuel efficiency of shipping goods via truck versus people in passenger vehicles driving to pick things up. Rummaging on Google I couldn't find anything with enough authority for me to add the numbers here, but if somebody finds those stats, they'd make a great addition to the article. Thanks, William Pietri 03:44, 17 July 2006 (UTC)

I found this article: http://www.mountain-plains.org/pubs/html/mpc-03-152/pg8.php which has some of the details requested by Billy above. You're welcome, Captain Milktoast 00:17, 10 March 2007 (UTC)Captain Milktoast

[edit] Rename the article ?

Is this article about semi-trailer trucks (as titled) ? Maybe I am reading this wrong, because I don't know this US English term first hand, but the title suggests that the article is about trucks insofar as they relate to semi-trailers. OK - I'm labouring this a little, but the article is (to my mind) titled about the truck itself (i.e. the prime mover or whatever else you want to call it). So what's all the stuff about trailers doing this article ? Trailer info is related useful info, but needs moving to somewhere else, no ? Unless the article is retitled, that is. My preference is 'articulated lorry', but then, no doubt, others would say 'huh?' to that, just as I'm scratching my head about the current title. --!!!!

See section 4 on this page. (This is section 9) G®iffen 10:23, 9 October 2006 (UTC)

In Australia, the subject of this article is usually known just as a "semi trailer", and formally (in road laws etc) as an "articulated vehicle". The topic of semi-trailer would actually be called either just "trailer", or "semi-trailer trailer" if it needed the context. The thing at the front is called a prime mover when it is not towing a trailer. --Scott Davis ^Talk 09:22, 7 January 2007 (UTC)

[edit] About the Container King Sidepicker System In Canada-link

I was wondering if this link is OK or too commercial. Personally I would prefer to see it replaced by a video clip or photostring showing how a sideloader works? Besides it's uploaded by a user of the same name as the company... G®iffen 15:09, 20 October 2006 (UTC)

I've just removed all the external links as they appeared to be commercial. If there's something useful in one of them, it should be added to the text and use the website as the footnote reference. My quick scan suggested they all failed the External links guideline. --Scott Davis ^Talk 09:26, 7 January 2007 (UTC)

[edit] trial in germany

there are 3 different trials in germany, one with only 40 metric tons, an other with 44tons and one with 60 tons maximum weight [Ecocombi#Deutschland] german wiki—The preceding []unsigned comment was added by 82.82.134.218 (talk) 21:05, 24 January 2007 (UTC).

[edit] Trucking in Alaska

I used to drive a truck in Alaska, and in the winter it could get extremly dangerous. I would like to know if anyone else ever had the promblem of the suspension freezing completely while parked overnight. This made my truck incredibly unsafe. Please let me know if you has this problem. =]

Thankyou, kind regards,
Zesty Prospect 17:46, 31 March 2007 (UTC)

[edit] "Semi"?

Why are they called "semi" trailers? Are they not full-sized trailers? —Ben FrantzDale (talk) 12:06, 19 December 2007 (UTC)

For some reason it's not explained before section 2.2 Construction. Somebody should put it up top somehow, but I'm not onto that at the moment... G®iffen (talk) 21:25, 24 December 2007 (UTC)

[edit] Cab over the engine

In the United States: how come back in the 1970s and 1980s nearly all tractor-trailer trucks were built with the cab over the engine and steer wheels... yet during the 1990s and 2000s those disappeared, replaced by the engine and steer wheels being placed ahead of the cab? This seems to be a rather major change and I'm surprised it's not mentioned in the article. -Rolypolyman (talk) 12:02, 11 May 2008 (UTC)