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Why Are Semi Truck Steering Wheels So Big? (Explained!)

The bigger the vehicle, the bigger its parts to offer better performance and driving experience. 

When it comes to semi trucks, they have a big steering wheel to handle efficiently and manipulate their large and heavy body better while driving.

But what if you try smaller steering for your semi truck, thinking it may be more comfortable for you to use? and believe it can still control the semi truck?

Is there any specific measurement needed when choosing a new steering wheel? Will there be significant changes when driving your semi truck if you decide to change to a smaller one?

If you ever wonder about it, some scientific explanations and facts explain why.

Here’s a short answer to Why are Semi Truck Steering Wheels So Big:

Semi-trucks typically have large steering wheels since it allows for easy turning of the front steer wheels. Since semi-trucks are heavy, a larger torque is required to turn the steer wheels of the vehicle. A larger diameter steering wheel allows for a higher torque generation for steering.

Why do Trucks have Bigger Steering Wheels than Cars?

Since trucks are heavier than cars, and steering wheels provide leverage to the vehicle, a bigger steering wheel is what trucks and semi-trucks need for a more effortless steering operation.

Heavier vehicles also take more torque or angular momentum on their front wheels. If they have smaller steering wheels, it will be hard to turn or change the direction when driving.

Do all Semi Truck have Large Steering wheels?

Technically, all semi trucks have large steering wheels. However, they do not have a fixed size. It will depend on the brand and model type of the semi truck.

Also, it may depend on your personal preference on which you consider to be large or not.

Can you Replace a Big Semi-truck Steering Wheel with a Smaller One?

One of the possible reasons you change the steering wheel on your semi-truck is if you find it too big to use. Yes, if that is the case, you can change it to a smaller one.

However, you may need to put a lot of steering effort every time you turn with a smaller steering wheel. You will need a lot of force and momentum to manipulate more oversized vehicles like a semi-truck. 

For a smaller steering wheel on your truck to be a little bit more practical, it is recommended that you equip it with a power or hydraulic steering system.

What Size is a Semi Truck Steering wheel?

Using the right size of the steering wheel for your semi truck can make your driving easier and smoother.

There is no fixed size in a semi-truck steering wheel, but it is often around 18 inches in diameter. There are slight differences in the size depending on your semi-truck brand, manufacturer, or model.

To give you a reference, the popular semi truck brands such as Peterbilt, Kenworth, Volvo, Freightliner, and Western Star all offer the ideal steering size for commercial semi trucks, 18 inches in diameter.

But you can find Peterbilt and Kenworth steering wheels with 16 inches and 20 inches diameter sizes in some stores or suppliers available in the online or physical market.

What are the components of a Semi Truck Steering Wheel System?

Bigger trucks require more effort and skills to maneuver compared to driving a typical commercial vehicle.

Thus, it is safe to say that larger trucks such as semi-truck have an overall better steering system and offer more controls and features to keep up with the difficulty of driving them.

The major steering components of a semi truck include the steering column, ball joints, drag links, front axle beam, kingpin, pitman arm, shims, steering arms, and steering gearbox. 

Modern semi trucks have additional components in power steering systems. It is to offer a much easier and more precise steering operation.

Do Semi Trucks have Power Steering?

Driving a massive vehicle such as a semi truck will also require enormous skills and power. 

That is why semi trucks also have a power steering system to lessen the force or effort needed to turn it and maintain its steering ratio.

There are three types of power steering in semi trucks: hydraulicelectric, and hybrid.

The hydraulic power steering uses compressed hydraulic fluid to increase your activity on the steering wheel to turn the wheels.

The source of its power is the hydraulic pump mechanically operated by the truck’s engine. The electric power steering uses various electric sensors and motors to operate.

While the hybrid power steering is a combination of the two, its power source is the hydraulic pump run by the electric mechanism of your semi truck’s engine.

Many people consider electric power steering the most reliable to use among these three.

Does Power Steering Affect the Size of the Steering Wheel?

Now that you know what power steering can do for more accessible and more precise maneuvering of a semi truck, you may think that maybe it can help reduce the size of the steering wheel.

The presence of power steering lightens the control of the steering wheel and does not affect its size.

As the vehicle gets bigger, it should also size up its steering wheel for easier turns.

Some drivers may find it hard to control a bigger steering wheel, which is when the power steering will come in handy.

How many Degrees does a Semi Truck Steering Wheel Turn?

When making a turn, a driver rotates the steering wheel in a spiral motion, and it sets off the transverse movement of the semi truck wheel.

The turn around a wheel ratio of 20:1 or 360 degrees steering wheel turns to about 18 degrees wheel rotation.

If the steering ratio is lower, you need to exert more energy to turn the semi truck while driving.

Why are Semi Truck Steering Wheels Horizontal?

Another question that curious people may ask is why the semi truck steering wheels are horizontal while it is almost vertical in cars. Are there any particular reasons behind it?

The main reasons are safety, ease of maneuver, and driver comfort.

The driver sits almost on top of the front wheels in semi trucks and other larger vehicles. The steering column is closer to vertical, so the wheels are more comparable to horizontal.

Another thing is setting up the steering wheels in a horizontal position is an ergonomic design to provide comfort to the hands, wrists, and arms.

Does the Orientation of the Steering Wheel Affect its Size?

The orientation of the steering wheel affects its size to provide better usage and control.

For example, since larger vehicles like semi-trucks have a more horizontal position, the force exerted to turn the car around can lessen. 

In comparison, the vertical position of the steering wheel is more appropriate for smaller vehicles since it only requires minimal effort to maneuver.

Are Small Steering Wheels for Semi Trucks Better?

Even though the standard size for a steering wheel in a semi-truck should be more prominent, maybe you want it to be smaller based on different factors.

A smaller steering wheel in semi-trucks will better work for drivers with smaller shoulders. In this way, it is easier to handle and prevent muscle tensions on the hands and arms.

It also offers a more ergonomic feel to make drivers feel more comfortable driving, especially on long-hour drives.

How can you Customize your Semi Truck Steering Wheel?

If you think that the typical size for steering wheels in a semi truck is just not for you, you can choose to customize it according to your preference.

Since you often interact with the steering wheel, make sure you feel comfortable when holding it. 

You can check aftermarket steering wheels for replacement. Before buying one, ensure the size and design are appropriate for semi trucks.

If you do not know how to do it or are unsure of the technicalities, you can consult your mechanic to help you with the customization.

With a better steering wheel designed to your liking, you can ensure a better driving experience with your semi truck.

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