different types of commercial trucks

What’s a Heavy Truck? Truck Classification Explained

In North America, trucks are categorized into 8 classes. Class 7 to Class 8 are classified as heavy-duty trucks. Trucks are classified based on the maximum loaded weight of the truck. This measure is based on the term ‘Gross Vehicle Weight Rating’ or GVWR. Read on to find out what a heavy truck is and what the underlying classification is.

How Does Truck Classification Work?

Heavy truck classification will typically be based on the GVWR. This is the way manufacturers label their trucks under government guidelines. It refers to the maximum truck weight and the load weight that the truck is capable of carrying when fully loaded. This includes the weight of everything including:

  • Cargo
  • Fuel
  • Passengers
  • Trailer tongue

Truck classification is there to help regulate safety. Besides, it is of use when registering a vehicle and for commercial designation. The GVWR is displayed on a placard on the driver’s side door.

GVWR of Heavy Duty Trucks

Class 7 to class 8 trucks are classified as heavy-duty trucks. The big rigs and other commercial vehicles belong to these categories. It is important to understand that the regulations related to what is allowed to drive/tow with your CDL license vary from one jurisdiction to another. In Quebec, you will require a minimum of Class 3 license for operating a heavy duty truck, and Class one for combinations of road vehicles (such as a road tractor or a truck covered by Class 3 hauling one or more trailers or semi-trailers).

Class 7 Heavy Trucks

These trucks have GVWRs ranging between 26,001 and 33,000 lbs. and they will mostly have 3 or more axles. Class 7 vehicles can include:

  • Garbage trucks
  • City transit buses
  • Street sweepers
  • Smaller semis
  • Furniture trucks

The Ford F-750 can be the perfect example of a Class-7 heavy duty truck.

Class 8 Heavy Trucks

Most of the trucks with higher GVWRs are classified under the Class 8 category. The bigger trucks with over 33,001 lbs. GVWRs belong to this category. In fact, they go beyond the class of heavy truck and are often referred to as severe duty vehicles. Some of the common examples include:

  • Dump trucks
  • Cement trucks
  • Tractor-trailer trucks

The big rigs such as Kenworths, Freightliners, and Peterbilts also belong to this category.

Vehicles Behind Truck Classification

The GVWR limit for Class 8 trucks seems open-ended, but that’s not the case. There is also a Class 9 category and it includes special-duty trucks and super-heavy trucks with weights exceeding 60,000 lbs. The maximum weight can vary on a case-by-case basis under the Federal Bridge Gross Weight Formula (FBGW Formula). This equation makes it possible for the safe transportation of longer and heavier loads across interstate highways. For example, a longer 18-wheeler can weigh up to 80,000 lbs. and may not seem to belong to any category. Heavy-duty trucks, when they pull a trailer, tend to have a gross combined weight of 80,000 lbs. or more.

Some jurisdictions also provide certain exceptions to the GVWR and per-axle limits based on the FBGW Formula. The loads belonging to such a category are placed under ‘oversized loads’. A heavy duty truck that addresses unique conditions is required to get special permits. Besides, such vehicles are required to travel along specifically designated routes.

Heavy Duty Trucks & Diesel Engines

In the domain of heavy-duty trucks, even diesel engines are classified into different categories. The diesel engines used in these vehicles are further categorized into the following service classes based on GVWR:

  • Light Heavy-Duty Diesel Engines or LHDDE: These engines are meant to be used in vehicles with GVWR 8,501 lbs. to 19,500 lbs. belonging to Classes 2B to 5.
  • Medium Heavy-Duty Diesel Engines or MHDDE: These diesel engines are designed to be used in vehicles with GVWR 19,501 lbs. to 33,000 lbs. belonging to the Classes 6 to 7.
  • Heavy Heavy-Duty Diesel Engines or HHDDE: These engines are made to be used in heavy duty truck with greater than 33,000 lbs. GVWR and belonging to Class 8 and higher.

Today, the semi-truck or tractor-trailer is the most recognized type of heavy truck. It was the first commercial designed during the 1910s.

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