A Guide to Semi-Trucks and Their Engines for Auto Mechanic School Students

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If you’ve been on a highway recently, then you’ll know just how common semi-trucks are on the road. These huge vehicles are hard to miss, and serve an important function that we simply mustn’t overlook—transporting goods across long distances on a regular basis, making sure that we get the things we need when we need them.

Due to their primary function, these trucks are designed with endurance and strength in mind. The first semi-truck dates back to 1898, when Alexander Winton designed a “car hauler” to deliver his cars to customers. Since then, semi-trucks have been relied on for all kinds of additional heavy-duty transportation needs. Here’s a closer look at these incredible vehicles and their engines.

The Basics of a Semi-Truck Engine and What Makes Them so Unique 

Semi-truck engines are in a league of their own, inherently different from engines found in regular vehicles. Unlike car engines, a semi engine is six times larger and heavier, with average specs including 400 to 600 hp, and torque ranging from 1000 to 2000 ft-lb. They were also manufactured with long distances in mind, with stops needed only for an oil change or to service the engine. 

Due to their larger size, semi engines are equipped to contain more oil, with many needing around 56 litres of the stuff to work. These vehicles come with more gears than a regular car, with an average of around 10 gears. This design inclusion makes it easier for the driver to maneuver the vehicle on various types of terrain and inclines. Unlike many other cars, standard semi-trucks also have turbochargers and an air-brake system. It’s interesting for those enrolled in auto mechanic school to know of these basic differences. 

An Insider Look at the Semi Truck Diesel Engine 

Semi-truck engines run on diesel, which provides them with better torque and hauling power. As diesel fuel has more useable energy, it can help with a semi truck’s fuel mileage—covering around 20% to 35% more ground per litre than gasoline engines. Further developments have been made to make diesel more environmentally-friendly. The Environmental Protection Agency (EPA) has proposed Ultra-Low Sulphur Diesel (ULSD), which aims to reduce sulphur emissions that are considered toxic for the environment. The use of ULSD is now widely used and regulated by the EPA for semi-truck engines.

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Semi-trucks typically use diesel engines

Semi-truck engines come in a wide variety of shapes and sizes, each with its own specs and reputation. Engines need to be durable and reliable, and are serviced by their respective dealers and manufacturers. With that in mind, some of the most popular semi engines include Paccar engines—13-liter engines that offer 500 hp and a maximum torque of 1364 lb-feet. Other notable mentions include the engines in Freightliner/Western Star trucks, as well as the DAF XF engine. 

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Diesel fuel has more useable energy, providing semi-trucks with better fuel efficiency

Other Facts for Students in Auto Mechanic School 

It should be noted that semi-trucks shouldn’t be running for too long despite being able to handle long distances and extended periods of time. Idling semi-trucks consume a lot of fuel, quickly increasing fuel costs. Of additional interest to students in auto service college, the fuel doesn’t completely burn as the truck idles—an aspect that can cause internal engine problems if the driver isn’t mindful.

Students interested in heavy-duty vehicles should keep an eye out for some exciting innovations happening in the industry. In 2017, Tesla revealed its plans to manufacture a semi-truck that uses an electric engine by 2021. While it’s hard to predict how popular these engines will be, it’s expected that they’ll provide trucks with around 480 km to 800 km per charge. 

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