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In 2018, only 2% of semi-trucks used an automatic transmission, with manual transmission being favored by fleet companies due to lower costs and drivers’ preference for feeling in control. Recent technological advancements mean there are three transmission options available for drivers and fleet owners now: Manual, Automated Manual, and Automatic. In the future, with the development of autonomous trucks, the transmission type may no longer be a concern, but for now, we’ll explore these different options.

In a 2021 poll by OverDrive Magazine, 72% of owner-operators used fully manual transmission, 16% used fully automatic, and 12% used automated manual. What’s the difference between these types of transmissions? Why would someone opt for one over another?

What’s the difference between these types of transmissions?
Why would someone opt for one over another?

Manual

Manual transmissions give full control of the truck to the drivers. Shifting demographics in the industry are challenging this, with many new drivers lacking experience with manual transmission – even in cars.

Less expensive than their automated manual and automatic counterparts, manual transmissions are the preferred industry standard for fleet owners. Due to this, most mechanics are familiar with repairing the common issues that occur with trucks on the road.

Some drivers claim that manual transmissions help keep them alert by ensuring they stay engaged with their machine and worry that if their transmission was automatic, they would relax on the road more.

Automated Manual

Roy Horton, director of product strategy at Mack Trucks, says about 94% of orders are now spec’d with automated manual transmission. Automated manual transmission (AMT) trucks have an enhanced manual transmission without the need to engage the clutch pedal when shifting gears – meaning there are only two pedals to control rather than three. An AMT uses software and hydraulics to automatically engage the clutch and control gears.

While AMT trucks may externally look similar to those with an automatic transmission, which also use a dual pedal system, AMT trucks have the same internal functions as a manual transmission – resulting in a slight pause when shifting gears and a lighter frame. The lighter frame allows drivers to haul heavier loads – often meaning they can earn more money.

Manual transmissions handle ice and snow better than automatic ones, but AMTs offer the best of both worlds: full control in the hands of the driver with the ease of a dual pedal control system. The computerized control of the clutch helps to improve and standardize fuel efficiency.

It can be costly to buy and maintain an AMT truck. Fewer semi-truck mechanics are familiar with the complex software that controls the clutch – manual transmissions have been the industry standard.

Fully-Automatic

Fully-automatic transmissions are the easiest transmission to learn and use, particularly for younger drivers who may have little to no experience with manual transmissions. The trucks are also safer – allowing the driver to immediately respond to changing weather conditions. For drivers who spend most of their time on stretches of highway in moderate weather zones, the automatic transmission may be preferable as it requires less technical skill to maneuver and is more fuel effective than manual transmission.

As with AMTs, the newer technology involved in fully automatic transmissions may make it more difficult to find mechanics who are comfortable working on all sorts of repairs.

Autonomous Trucks

Autonomous trucks are not readily available for the general public yet, but over the past few years, experiments have shown the near possibility of autonomous, or self-driving, semi-trucks becoming a reality. Right now, TuSimple offers autonomous trucks that can conduct driving tasks and monitor the environment but can only operate under certain conditions.

At the moment, autonomous trucks are simpler to operate on an interstate than throughout the first and last miles, when a human driver often needs to take over. Bad weather impacts autonomous maneuverability, resulting in “edge cases” where the truck is unable to anticipate what to do and pulls itself over to the edge of the road. Currently, autonomous trucks are being tested in Arizona, New Mexico, and Texas, where the chance of “edge case” weather is low.

Conclusion

No matter which level of automation a driver or fleet manager selects for their trucks, there comes are significant benefits and some drawbacks to each. People must consider the safety of the roads, the skills of their drivers, and the costs associated with the initial purchase, maintenance, and fuel.

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