Interesting Facts About Semi Trucks and 18-Wheelers

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Facts About 18-Wheelers
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Legal weight for an 18-wheeler

The legal weight for an 18-wheeler is 80,000 lbs. [40 tons].[ 36287 kg Canadian] That is without any oversize or overweight permits.  In comparison,  the average automobile weighs over somewhere around 5,000 lbs.
legal U.S. weight per axle is:  STEER 12,000 lbs  DRIVES 34,000 lbs  TRAILER 34,000 lbs
legal Canada weight per axle is:  STEER 5443 kg  DRIVES  15422 kg  TRAILER 15422 kg

Length of 18-wheelers

The average length of an 18-wheeler varies greatly depending on the type of cab they are driving.  But the overall average is 70-80 ft. long.  The length of an 18-wheeler’s cab [by wheelbase] usually averages between 245″ to 265″ wheelbase.  This is measured from the center of the rear wheel to the center of the steer.

Length of time needed to stop an 18-wheeler

The length of time to stop an 18-wheeler is 40% greater than that of an automobile.  Depending on the weight of their load,  whether they are bobtailing,  road conditions,  and other factors.  To be sure,  it takes a much greater time to stop than an automobile… period.  Trucks only have 10 brakes NOT eighteen as some have told me they thought.  Trucks made now are required to have anti-lock brakes.

What is the turning radius of 18-wheelers?

Click HERE for more information on the turning radius of 18-wheelers.

What does an 18-wheeler cost?

While there are myriad variables on the costs, the CAB of an 18-wheeler usually ranges from $130,000 to $180,000 new. New trailers usually range from $30,000 to $80,00. So all in all you could be paying over a quarter-million dollars for a new truck and trailer.

What is the “fifth wheel” ?

18-Wheelers Fact: Fifth wheel

The fifth wheel on an 18 wheeler is a round plate above the drive tires that couples [hooks together] the trailer to the truck.

How many gears does an 18 wheeler have?

The most common amount of gears in an 18 wheeler today is 10 forward and 2 reverse gears.  Although they can range from 9, 10, 13, 15, and 18 gears!

Eighteen-wheeler drivers use a “double-clutch” technique for shifting.  It is much different to drive a truck compared to a car with a standard transmission.  In a car the rpm’s match up and in a truck they do not therefore the clutch is depressed and then depressed again to “match” the gears with the rpm’s.  Most drivers use what they call “floating” which does NOT use the clutch at all except to start and stop.  “Floating” is an acquired skill that takes some practice to get used to.  “Floating” gears saves fuel (when done properly) and saves wear and tear on the equipment.  “Floating” is the preferred method.

What is “bobtailing” ?

18-Wheelers Fact: Bobtailing

Bobtailing is the term used when a truck is driving WITHOUT the trailer attached.

This is very dangerous especially in wet weather but obviously must be done at times.

What is the standard height of an 18-wheeler?

The standard height of 18-wheelers is:  13′ 6″

What Is A Tandem ?

18-Wheelers Fact: Tandem

Tandem sometimes incorrectly refers to a set of TWO tires (Pictured) on a tractor-trailer. However, these are more commonly known as double wheels, dual tires, or ‘dualies.’  They are used for safety (redundancy) so if one tire blows the others will continue to hold up until the tire is repaired.

The correct definition of Tandem is a set of two axles, with one axle immediately following the other.  By distributing the load over two axles, each axle bears less weight.  Because there are laws limiting the amount of weight that can be carried on each axle, distributing the weight over more axles allows a greater total amount of weight to be carried.

What Is A Jack-Knife Accident?

Basically, a jack-knife accident is when the trailer contacts the tractor by the trailer “coming around” on the driver. It is said that once a trailer exceeds a 45 degree angle, compared to the tractor, that a jack-knife is inevitable. This can be caused my many things and happens when the trailer wheels start to skid and actually ends up moving faster than the cab. Usually this happens on icy or wet roads but it can happen on dry roads when the trailer is empty and the driver has to do some very hard braking.

18-Wheeler Truck Manufacturers

There are a variety of brand names for 18-wheelers; among them are: PeterbiltFreightlinerKenworthVolvoMackWestern Star, to name a few more popular trucks.

How Many Axles Does An 18-Wheeler Have?

An 18-wheeler has a total of five (5) axles.

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