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How Do Truck Suspension Systems Work?

Dec 15, 2021 ·

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Every system in a vehicle is important and plays a role in maintaining performance. The suspension system helps contribute to the handling and stability of a vehicle while on the road.

While the purpose of car suspension and truck suspension systems are the same, the system itself is different between these two types of vehicles. Keep reading to find out more about truck suspensions and how they operate.

Why Truck Suspensions Are Important

When it comes to heavy-duty vehicles like work trucks, the suspension system plays a critical role in helping support the different operations the vehicles perform.

Pickup truck suspension systems are responsible for supporting the load being hauled by the vehicle. Often, these vehicles carry large amounts of equipment or products, so the suspension needs to be durable and reliable enough to handle it.

Truck suspensions also are crucial for providing stability on the road. Since these vehicles are heavier and might also be carrying additional weight, the suspension must be able to assist with handling uneven roads. The suspension also helps prevent trucks from tipping.

The suspension also needs to help cushion the ride so the cargo and equipment remains protected over bumps and other imperfections in the road. Cushioning the ride also helps improve driver comfort.

The suspension allows the tires and axles of the truck to move independently from one another, instead of the axle being attached to the frame directly. This helps soften the impact to the vehicle and helps absorb the impact of cracks, bumps or dips in the road.

Types of Truck Suspensions

There are a few different kinds of truck suspension systems that can be used depending on the application the vehicle is handling:

Leaf spring suspension

A leaf spring suspension system is one of the earliest systems and features long, arched pieces of steel that flex when needed. The leaf spring system is attached to the frame and a shackle that moves, which allows the length of the spring to vary.

More leaf springs can be added to support more weight. Heavy-duty trucks or other diesel vehicles often feature multiple layers of leaf springs if they have this type of system.

Pictured here is a leaf spring suspension setup, which is the most common type of suspension system used on big-rig trucks:

Torsion bar suspension

Torsion bar suspensions feature a narrow steel tube attached to the wishbone of a vehicle that twists around its axis. The tube is also attached on one end to the chassis, and this end does not twist. If a wheel hits a bump, tension gets created when the tube twists. After a bump, the steel unwinds and pushes the wheel down again.

Coil spring suspension

A coil spring suspension is a common system that is found in the front and back of many vehicles and in the front of some trucks. These systems feature springs that are spiraled and allow for flexibility in the form of bending and twisting. They are the most versatile system.

Truck rear suspension

While the go-to move for a while was to install leaf suspension systems on the rear of pickup trucks, coil spring suspension systems installed on the rear of vehicles became popular when Dodge introduced them on their 2009 Ram 1500s. These systems combine a lot of weight-bearing capability with comfort.

Signs of Wear on Truck Suspensions

There are several signs that can indicate wear and tear on a truck’s suspension system. Paying attention to these is important so you can catch issues early:

  • Bumpy rides: An increase in bumpiness and shaking on the road can mean there’s damage to the struts or other parts of the suspension.
  • Uneven tire wear: Suspension issues can cause uneven impact on your vehicle, causing irregular tire wear and tear.
  • Rocking: Noticing your truck rocking forward, backward or sideways when stopping or turning can be a sign of a suspension that is unable to properly stabilize motion.
  • Lowered vehicle: If you notice a sunken frame or your truck leaning to one side or the other when it’s parked, there could be damage to the suspension.
  • Leaking oil: Finding leaking oil on the shocks of your truck can be an indicator they are worn or damaged and need to be replaced.

Be sure to take your truck to a trained diesel technician who has the expertise to diagnose and repair suspension issues. This will ensure your vehicle is riding properly and that you remain safe on the road.

Train on Heavy-Duty Suspensions at UTI

With more than 28,000 estimated average annual diesel job openings in the United States,43 you could train to become one of the professionals equipped to work on heavy-duty suspensions and more.

The Diesel Technology program at Universal Technical Institute teaches students how to diagnose and perform repairs while training for a career as a diesel technician.1 The Diesel Truck Steering & Suspension Systems course covers the basics of how suspensions work and how they’re put together.

You can graduate in as little as 45 weeks7 with the hands-on experience necessary for an entry-level career. Find out more about the program here!

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1) UTI is an educational institution and cannot guarantee employment or salary.

2) For program outcome information and other disclosures, visit

7) Some programs may require longer than one year to complete.

43) For Bus and Truck Mechanics and Diesel Engine Specialists, the U.S. Bureau of Labor Statistics projects an annual average of 28,500 job openings between 2021 and 2031. Job openings include openings due to net employment changes and net replacements. See Table 1.10 Occupational separations and openings, projected 2021-31, U.S. Bureau of Labor Statistics,, viewed October 13, 2022. UTI is an educational institution and cannot guarantee employment or salary.

Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.


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