smiling delivery truck driver while holding gear stick

Manual vs Automatic Transmission for Semi Trucks – Which is Better?


The most critical part of a semi truck is its transmission. It regulates the amount of power going to your wheels. Such powers drive semi-trucks’ efficiency. In 2019, around 85% of semi-trucks used automatic transmissions. The main reason behind this is the convenience it gives to drivers. Technology improves the automation of a truck’s transmission. Computers are now more precise in evaluating speed and torque when shifting gears. Still, 15% of semi-trucks use manual transmissions. During tough driving conditions, drivers have more control over manual brakes and gears. Let’s see which is better for a semi-truck: automatic or manual transmissions?

What is a Semi Truck Transmission?


A semi-truck transmission is the power control of its engine. It allows the semi-truck to change gears. When changing gears, it transmits power from the engine to the axles. Lower gears mean high engine power over slow speed. Higher gears mean low engine power over fast speed. As such, it enables the transmission to supply power most efficiently. There’s no consensus if an automatic or manual transmission is better. But automatic transmissions are commonly preferred in all types of vehicles including semi-trucks. 

What are the Types of Semi Truck Transmissions?


There are two common types of semi-truck transmissions. These are the automatic and manual transmissions. The third type of transmission is recently on the rise. It’s called the Automatic Manual Transmission (AMT), a combination of the two common transmission types.

Manual Transmission


Semi-trucks with manual transmissions use slider gears allowing the driver to engage it without perfectly matching RPMs. Drivers typically start at a low range shifting to a high range one gear at a time. They have a built-in two-speed pneumatic control.

Automatic Transmission


Semi-trucks with automatic transmissions get rid of manual shifting by using a computer-control feature. It allows engaging at the perfect RPMs. They have a two-pedal design controlled by a hydraulic system.

Automatic Manual Transmission (AMT)


The third type of transmission on the rise is called an AMT. They’re a combination of an automatic and a manual transmission. The gear uses mechanical control while the clutch and fork use automated actuators, computers, and sensors. These types of transmissions are not yet popular on large vehicles like semi-trucks. It’s still in the experimental or testing stage.

Pros and Cons of a Manual Transmission on Semi Trucks


Generally, semi-trucks with manual transmissions cost lower than those with automatic transmissions. They also have lower fuel and maintenance costs. They use less fuel compared to an automatic transmission. They need fewer oil changes. Drivers have better control especially if they’re fast and skilled in shift responses. Semi-trucks with manual transmissions have better traction in mud, slippery roads, and snow. Drivers can easily rock the truck out when stuck on these types of roads using the stick shift. It’s also easy to apply brakes on semi-trucks with manual transmissions. It’s because semi-trucks with automatic transmissions are designed to move forward whenever it’s on “drive.” 

On the other side, semi-trucks with manual transmissions are difficult to learn. It may take time to get familiar with a stick system. It requires fast foot and hand movements. It also takes skills to master synchronizing the clutch and gears. When driving a semi-truck on a steep hill, it’s harder when using manual transmissions. Unlike automatic transmissions designed to move forward when in “drive”, manual transmissions tend to roll backward. This makes it hard for the driver to push the clutch and shift forward. For drivers, it can get tiresome to constantly shift gears with a semi-truck using manual transmissions in heavy traffic. 

Pros and Cons of an Automatic Transmission on Semi Trucks


The main difference between a semi-truck with automatic and manual transmissions is the clutch. Semi-trucks with automatic transmissions don’t have a clutch on the floor. Instead, they use processors and sensors to disengage the engine from the wheels. Such features offer a better driving experience and easier gear shifts. Semi-trucks with automatic transmissions are also safer to drive. There’s less distraction because drivers don’t need to worry about synchronizing the clutch and gear shift. They can keep both hands on the wheel. It’s unlike manual transmissions where the driver’s right hand is most of the time holding the stick. 

For those who are conscious about fuel and maintenance budget, a semi-truck with automatic transmissions may have higher fuel and maintenance costs than those with manual transmissions. Automatic transmissions are short-lived compared to manual transmissions. They need regular tune-ups and more fluid changes. They encounter more electrical problems. It’s because their components are more sophisticated. Most of the time, it’s better to replace an automatic transmission than having it repaired. Their parts are expensive and cost almost the same as the whole transmission. Semi-trucks with automatic transmissions have lesser traction in mud, slippery roads, and snow. It will be hard to rock the truck out when stuck on these types of roads.

Which is Better on Semi Trucks: Manual or Automatic Transmission?


Most semi-truck drivers prefer automatic transmissions over manual transmissions. It’s because they are easy to learn. They also offer better acceleration, convenience, more strength, and torque conversion. Automatic transmissions shift faster than the blink of an eye. Drivers are more relaxed in the absence of a distracting clutch. Their engines are more powerful because of the sophisticated design. Semi-trucks with automatic transmissions are ideal for city driving, heavy traffic, and uphill.

Some drivers prefer semi-trucks with manual transmissions. It’s because they offer more control in tough driving conditions. They’re also preferred by budget-conscious people. It’s because they cost cheaper and have lesser fuel and maintenance expenses than automatic transmissions. They also need fewer oil changes. Manual transmissions often last longer than automatic transmissions. They are great for off-road driving. They also have better traction on muddy, slippery, and snowy roads.

Even though most drivers prefer semi-trucks with automatic transmissions, it doesn’t mean that they’re better than semi-trucks with manual transmissions.

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