Inflight smoking is forbidden not just for the comfort of non-smokers – there are actually technical reasons behind it

Inflight smoking is forbidden not just for the comfort of non-smokers – there are actually technical reasons behind it

Several decades ago flying was much less glamorous than it is now. Sure, people used to dress up for the journey, but everyone was smoking. Now we can appreciate fresh, even if a little bit dry, air in airplane cabins. But did you know that smoking in airplanes was prohibited not just to make flying more comfortable for non-smokers?

In fact, smokers in the airplanes didn’t bother people too much. They were typically seated at the rear of the cabin, where they could smoke without disturbing non-smoking passengers. Because air inside of an airplane is flowing from the front to the back smoke was evacuated pretty effectively, without filling entire cabin with unpleasant smell. When in 1988 smoking was banned from flights that are shorter than 2 hours, airlines were actually worried that people are going to fly less because of this decision. And now if you do try to light up a cigarette, you are facing a huge fine and/or ban from flying that airline again. Why is that?

Back in a day, you could buy cigarettes from flight attendances. That contributed to revenues of the airlines, which is why they were against in-flight smoking ban. Tobacco companies were also vocal about their disapproval or such decision. And, of course, smokers felt discriminated, especially when the ban included pretty much all longer flights. However, not airlines are very happy that no one is smoking in the airplane.

Smoking in planes was completely normal not so long ago. (Estormiz, Wikimedia)

The truth is that smoking costs money not only to people buying cigarettes, but also to airlines, because it increases the cost of plane maintenance. Smokers unintentionally drop ashes on the carpet, they fill up the ashtrays, sometimes damage the seats and so on. Cleaning airplanes that have been smoked in is more time consuming. Also, remember we said air flows from front to back?

The airplane cabin, as weird as it may seem, is not a completely sealed pressure vessel – it does vent out. The air pressure inside of the cabin is equal to the one at altitude of around 2-2.4 km. Air is constantly pumped into the cabin and so, some it has to be vented out through the main cabin outflow valve. The opening and closing of this valve is what controls the pressure inside. However, tobacco smoke can make this mechanism sticky. Thick sticky tar used settle all over the main cabin outflow valve. Sometimes it became so sticky that the system struggled to open it.

Now smoking in the airplane could result in a huge fine and even a ban to fly that airline ever again. (Kashif Mardani, Wikimedia(CC BY 2.0)

Furthermore, tobacco tar used to cover all the airways from the cabin, which were a significant hassle to clean during maintenance. Finally, smoking could have posed a safety threat as well, if the tar glued the oxygen mask compartment doors too. Pilots used to smoke back in the day as well, but that wasn’t doing any good for electronics.

And so now smoking in most airlines is forbidden. However, ashtrays in bathrooms still exists. They are there just in case someone breaks the rules. If there were no ashtrays and someone decided to smoke, they would probably put their cigarettes out on the toilet or in the sink, which someone would have to clean up later.

Why this funny-looking tractor has only three wheels? (Video)

Why this funny-looking tractor has only three wheels? (Video)

Most tractors have four wheels. That is a standard configuration and deviations from it can only be found in history. However, there are exceptions – the Challenger Terra Gator TG 8333 is a modern machine and yet it only has three wheels. Why? What does it do?

Challenger Terra Gator TG 8333 is a self-propelled nutrient application vehicle. In other words, it spread fertilizer on the fields and does that very efficiently just because of how huge it is. It has telemetry equipment, adaptive suspension, GPS-controlled autopilot and loads of other technology.

The tractor in the picture below is spreading hard organic fertilizer- manure, but some other modifications can be used to spray liquid fertilizers. In fact, one three-wheeled Terra Gator can hold as much as 16 cubic meters of liquid fertilizer – that is more than 16 tons of weight.

Each of the three wheels is in its own track and thus the ground get driven over only once. (joost j. bakker, Wikimedia (CC BY 2.0)

Despite the massive size of this Terra Gator, it is supposed to be easily controlled. After climbing a set of stairs, the operator will find a comfortable workplace with a supportive seat, touchscreen, climate control and other equipment. But we are not selling you this tractor – we are more interested, why it has only three wheels.

All three wheels of the Challenger Terra Gator TG 8333 are the same size and all are driven. (werktuigendagen, Wikimedia (CC BY-SA 2.0)

The reason why Challenger Terra Gator TG 8333 has three wheels is weight distribution. Farmers do not want to compact the soil, especially when they are ready for fertilizing. It is harder for crops to grow in a compacted ground and heavy equipment squeezes out the air from the dirt, essentially reducing the harvest. Four-wheeled tractors may have a better weight distribution, but the rear wheels are following the front ones and, therefore, dirt that gets under the wheels gets driven over twice. It is also the reason why Challenger Terra Gator TG 8333 has such wide tires – they spread the weight of the machine over a bigger area.

Challenger Terra Gator TG 8333 at work


Other manufacturers apply different solutions to solve the issue of compacting the soil. Some use narrower front axles, while other fertilizers employ dual wheel arrangements. And then there are farmers who simply use lighter machines to not compact the ground too much.

Interestingly, Challenger Terra Gator TG 8333 is all-wheel-drive – all three wheels are driven. The front wheel, used for steering, is powered hydrostatically. Three-wheel configuration also allows for a better manoeuvrability – the front wheel can be turned by 75 degrees – it would be difficult to achieve that having two front wheels.

Why semi-trucks are called like that? What is so “semi” about them?

Why semi-trucks are called like that? What is so “semi” about them?

We use words without paying much attention to them. For example, words “semi-truck” are used commonly, but how many people know what that means? What is “semi” about these machines? There are actually two possible explanations.

In US and some other countries semi-trucks are simply referred to as Semi’s. It is a name everyone understands and once you mention a semi-truck everyone has an image in their heads of an articulated vehicle, consisting of a tractor unit and a trailer. Actually, the trailer is part of the story why semi-trucks are called like that.

Semi-trucks are, most of the time, hauling semi-trailers. A simple trailer is a wheeled platform, which can stand on its own on its wheels without any support. Meanwhile semi-trailers only have wheels at one end of the platform. The other end relies on the chassis of the semi-truck for support when driving. It cannot stand by itself on its wheels – it needs extendable legs or some other type of support structure. Semi-trailers cannot be hauled by anything else – they need an appropriate semi-truck to move. Even if you took the most powerful agricultural tractor, you could not safely pull a semi-trailer, because the front of it doesn’t have wheels and needs a chassis to rest on when travelling.

Semi-trucks consist of a tractor unit and a semi-trailer. Image credit: PRA via Wikimedia(CC BY 2.5)

But that is just a part of the explanation. Semi-truck is a combination of a semi-trailer and a tractor unit. Not that difficult to understand and it totally makes sense. But there is another explanation for where did this name come from.

The hitch mechanism at the back of the semi-truck is commonly called a “fifth wheel”. There are two most common types of fifth-wheels: semi-oscillating and fully-oscillating. Most semi-trucks feature a semi-oscillating hitch (turntable hitch or fifth wheel – whatever you want to call it). It means that the hitch mechanism is not entirely rigid – it tilts slightly from front to back. Imagine that the rear of the semi-trailer gets a little bouncy and starts moving up and down. The fifth-wheel will accommodate that movement, making the entire truck more stable. But if the trailer is tilting sideways, the semi-oscillating hitch will not move with it – a semi-oscillating hitch does not tilt from side to side. It is not usually a problem, though, because semi-trailers typically have enough flexibility in their chassis to absorb lateral movement without disturbing the balance of the tractor unit.

Logging trucks sometimes use fully-oscillating hitches. Image credit: ChattOconeeNF via Wikimedia(CC BY 2.0)

However, in some situations a fully-oscillating hitch has to be used. For example, in forestry semi-trucks. Because the terrain is so uneven, semi-trailers get rocked quite a lot. A fully-oscillating hitch tilts from side to side and thus allows for more movement in the trailer without disturbing the truck. This is also beneficial when the semi-trailer is very rigid (for example, when it is a tanker). However, fully-oscillating fifth-wheels are more complex, more expensive and typically unnecessary, which makes them pretty rare. That could be why semi-truck name stuck.

The reason why semi-trucks are called this name is probably combination of both of these theories. You should remember that a typical semi-truck is an articulated vehicle, consisting of a tractor unit and a semi-trailer, connected through a semi-oscillating hitch.

Renault will begin selling electric trucks in 2019 – it is going to be an exciting year!

Renault will begin selling electric trucks in 2019 – it is going to be an exciting year!

Truck electrification is beginning to reach its stride. Companies are in some sort of a race, which will result in a lot of new electric trucks being introduced next year. You‘ve heard of Tesla Semi, Cummins Aeos, Daimler and maybe even Volvo‘s plans to introduce new electric trucks in 2019. And now Renault is joining the crowd.

It would be easy to think that Tesla started this trend with its Semi – a super fast and efficient semi-truck, which can reach 97 km/h in just 20 seconds while pulling a heavy load. However, this impressive machine was not the first electric truck to be announced. For example, Daimler has been experimenting with electric technology in its trucks for quite some time already. The main focus of Daimler is different than the one Tesla. Daimler is looking forward to introduce electric urban delivery trucks, which are smaller and typically travel smaller distances every day. Cummins had a similar idea when it introduced its Aeos – a day cab semi-truck with a range of around 160 km.

It seems that this trend is here to stay. Numerous manufacturers proved that electric heavy duty trucks are actually possible. Furthermore, they can be relatively affordable and easy to live with. If everything works as expected, Tesla Semi might actually be one of the most reliable semi-trucks in the market. Meanwhile big current manufacturers were not so vocal about their plans to start production of electric trucks.

Tesla Semi is probably the single favourite electric truck in general population. (Tesla’s picture)

Have you heard about electric trucks from Scania, MAN, Peterbilt and other giants of the truck industry? No. While there are certainly some plans, they are not developed to the stage of Tesla Semi or Cummins Aeos or even Nikola One. This new segment is up for grabs for the new players. However, some interesting projects are already coming from the well-known truck manufacturers.

Volvo Trucks has announced that it will introduce an electric urban distribution truck in 2019. While long haul machines are certainly in the plans, Volvo believes that city operations is where the electric trucks could thrive. In fact, Volvo said that electric urban distribution trucks could even work at night, helping to reduce city noise and congestion. And now finally we heard from Renault.

Cummins is a famous manufacturer of heavy-duty engines, but its Cummins Aeos truck is going to be one of the first urban delivery semi-trucks on the market (Cummins’ picture)

Renault Trucks has just announced that it will launch a new electric truck range in 2019. Pretty much at the same time when many other companies are going to introduce their first electric trucks – it is going to be an interesting year. However, Renault is not just following current trends. This company has been experimenting with electric technology since 2009, so it is about time to introduce some products into the market. For now the range will consist of urban and peri-urban delivery trucks. They are unlikely to feature such an extreme design like Tesla Semi or Nikola One. The reason is that smaller trucks do not have such big cabins, so there is not much room for extravagant design opportunities. However, we do expect some rounded corners, lack of big grill and some interesting paint schemes.

Renault has been experimenting with electric trucks since 2009 (picture of Renault Trucks)

So let’s see what we have. Daimler is preparing electric urban delivery trucks for intercity operations, Volvo is focusing on urban delivery and Renault is going to do a little bit of both. None of the major truck manufacturers in this article are preparing big semi-trucks, not even with day cabs. What does that mean?

It simply means that the old, trusted brands are letting new players to take on this market segment. They can jump on-board at any point they want, but for now they will just sit back and look how new manufacturers are going to do. Who knows, maybe smaller urban delivery trucks is actually a smarter step to this new age of electric trucking.

Why semi-trucks in US and Europe are so different?

Why semi-trucks in US and Europe are so different?

American and European semi-trucks are very different. You don‘t have to be a truck enthusiast or have brilliant understanding of the mechanical part of these machines to see that semi-trucks used in USA and Europe look very different. But why? Why different ideas about what the truck should look like prevailed in different places in the world?

The main difference you see is the overall design of the tractor unit. In Europe we usually see cab-over trucks. This means that the cabin is situated above the engine. This allows creating flat front surface and the entire truck with its trailer has a cuboid shape.

Meanwhile trucks used in US, Australia and in many other places in the world feature something called “conventional cab” design. This means that the cabin is behind the engine. Drivers are sitting further away from the actual front of the truck and look over the long engine cover when driving. So why in different places in the world different designs prevailed?

One of the differences between European and American trucking is that owners-operators are very common in US and not so much in Europe. These people own their own trucks and pretty much live in them for months at a time. Semi-trucks with conventional cabs feature longer wheel base, which makes them a little more comfortable. Also, they tend to have a lot of room inside. Owners modify their trucks to include huge living compartments – something not common in Europe. Without the engine under the cabin, getting in and out of the truck is actually easier, because the cabin is a little lower.

This is what conventional cab trucks look like – these are much more common in US, Australia and elsewhere outside Europe. (First Response Team of America, Wikimedia(CC BY-SA 3.0)

Another advantage of a conventional cab design is that the truck can be more economical. Surely they usually pull heavier loads, but if there were two trucks, one a cab-over and another one a conventional cab design, and they had the same powertrain and the same cargo, the conventional cab truck would most likely use less fuel. Of course, that is just in theory – in reality there are too many factors to consider.

Finally, engine in conventional cab trucks is easier to maintain and fix because it is very easy to reach. However, cab-over trucks do have their own advantages.

Cab-over trucks are simply more compact and easier to navigate through tight city traffic. (Volvo Trucks)

Square shape of the cab-over truck means that it is easier to place the truck close to other vehicles or objects. European semi-trucks are also lighter and have a shorter wheel bases, which makes them significantly easier to manoeuvre. Essentially, they are more compact and easier to work with in traffic and urban environments. But what are other reasons why different truck designs prevailed in US and Europe?

This is what the interior of a modern semi-truck looks like:


Why European and American trucks are so different?

Maximum length of a truck with a semi-trailer in Europe is 18.75 meters. Some countries have some exceptions, but generally that is the rule. In order to use the maximum of this length for the cargo the tractor unit has to be as short as possible. The best way to achieve that is to mount the cabin over the engine.

Similar requirements in US have been revoked back in 1986 and trucks now can be much longer. Actually, back in the day cab-over trucks were quite popular in US, but without strict limitations roomier and more convenient to live with conventional design trucks prevailed. The number of cab-over trucks in US is constantly declining.

Trucks of owners-operators typically have big living compartments. Meanwhile in Europe space is at a premium. (Pierre André, Wikimedia)

Another reason is speed. In Europe Semi-trucks are limited to 90 km/h, but in some places in US trucks reach 129 and even 137 km/h. That is where better aerodynamics and longer wheel base help a lot.

Finally, roads in US and Europe are very different as well. Cities in US have wide streets and interstate highways are very straight and wide. In Europe trucks have to deal with narrow streets, winding country roads and cramped parking spaces. Lack of space limitations allowed Australia to use conventional cab trucks too. That is also why Australian highways feature well-known road trains – extremely long distances and straight roads allow semi-trucks to pull up to four trailers.

Interested in trucks?

Volvo thinks electric trucks will help fighting traffic jams;

Electric trucks from a 100 years ago;

Gas-powered trucks are already available and in theory can be CO2 neutral;

Scammel Scarab – it is not your ordinary semi-truck – it is the mechanical horse;

General Motors Bison – a vision of trucks of the future from 1964. Why didn’t it stick?

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