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While cars with a manual transmission are few and far between in America, semi-trucks still heavily rely on that transmission. In fact, manual transmissions are just starting to be phased out and replaced with automatics. After all, automatics are easier to use. But why would semi-trucks rely on manual transmissions anyways?

American semi-trucks
American semi-trucks | Tim Graham via Getty Images

Why do semi-trucks use manual transmissions?

The answer is simple: manual transmissions are cheaper. They don’t have as many parts, which makes them cheaper to build. And they’re more durable, which is incredibly important when you’re hauling 80,000 lbs. Those gears are under a lot of stress, and you don’t want them going out on you while you’re driving.

Many long-time truckers are also just used to driving manual transmission vehicles, from cars to trucks. The average age of a truck driver is 55 years old, which means they were born in 1966 and driving by 1984. Chances are, they grew up around a manual transmission car. According to the EPA, 25% of all new cars sold in 1985 had a manual transmission.

So these seasoned drivers have no trouble operating a semi-truck with a manual transmission. However, the transmissions used by semi-trucks are vastly different than the ones used on regular cars.

How do manual semi-truck transmissions work?

Because semi-trucks haul heavier loads, they often have more gears than conventional cars. As of late, semi-trucks can have up to 18 gears. By comparison, many cars like the Ford Mustang have 10 gears (automatic transmissions can handle more ratios). So how exactly do these complex semi-truck transmissions work?

In truth, semi-truck transmissions are kind of like having two transmissions in one. Typically, you shift just like a normal car but have a high range and a low range. The video above highlights the idea that you have a certain number of gears for starting off, and then more gears for highway speeds or accelerating under heavy loads.

Semi-truck transmissions are much more complicated than “they have more gears,” as sometimes the air pressure inside the gearbox is so high, it can shift gears semi-automatically. However, as seen above, many seasoned drivers make shifting gears look effortless.

As semi-truck technology advances, automatic transmissions will become standard. And today, there are more reasons to drive an automatic transmission semi-truck than a manual one.

Why automatic semi-truck transmissions are becoming more important

Semi-truck and car driving down highway
Semi-truck and car driving down highway | Lane Turner/The Boston Globe via Getty Images

This Is America’s Best-Selling Semi Truck Brand

Automatic transmissions are safer, easier to use, and more efficient. The only major downside to an automatic transmission semi-truck is that they’re more expensive to build and maintain.

No, semi-trucks aren’t exactly the most fuel-efficient vehicles. That said, automatics are programmed to squeeze every last mile out of the trucks, whereas manuals rely on the driver to be good. And in case you weren’t aware, driving a truck isn’t exactly easy.

However, the main reason trucking companies need to adapt to automatic semi-trucks is because there’s a bit of a shortage going on. Currently, 80,000 truck driving positions need to be filled, and very few people even know how to drive a manual. Obviously, all prospective truck drivers have to go to school for it, where they’ll learn how to drive a manual semi-truck. If you want to cast a wider net, and make lives easier for the new drivers you’re hiring, they should be able to use an automatic.

Automatic transmissions in semi-trucks will continue to evolve. But for the time being, manual semi-trucks rule the road. So the next time you see one on the highway, remember that the drivers are most likely rowing their own.