Photo courtesy of ATRO Engineered Systems
Torque rods have bushings at each end to connect to other components while remaining slightly flexible.

Basic component, advanced materials

Feb. 4, 2019
Using bushing materials such as polyurethane can increase the life of the torque rod and related suspension components.

An important function of any heavy duty vehicle suspension is maintaining proper ride height. A vehicle with a ride height out of specification runs the risk of accelerated component wear, especially within the drivetrain. Using components made from advanced materials such as polyurethane can extend the life of the suspension, ensuring proper ride height to protect the rest of the vehicle.

“Ride height affects driveline angles which can [lead to] universal joint wear/failure, yoke damage, pinion seal leakage,” says Skip Steffen, vice president of sales for ATRO Engineered Systems, a parts manufacturer specializing in heavy duty truck and trailer suspension components.

A vital component to maintaining proper ride height and driveline angle is the torque rod, a metal bar in the suspension that restrains the axle during acceleration and braking, and controls the driveline angle. Torque rods have bushings at each end to connect to other components while remaining slightly flexible. Bushings are typically made from a softer material that is able to absorb shock and vibration, and this material can eventually wear out.

“Worn torque rod bushings can cause damage to load carrying suspension components like rubber load or bolster springs, as well as air springs on air ride suspensions, affecting the ride height,” Steffen says.

He advises that using advanced torque rod bushing materials such as polyurethane can greatly increase the life of the torque rod and related suspension components.

“Rubber does not have the physical properties or strength to operate in a heavy duty application without compressing the material to increase its load handling capabilities due to the internal porous amorphous structure,” says George Sturmon, founder of ATRO. “Polymers, on the other hand, have a non-porous carbon chain structure that provides physical properties far in excess of rubber. In addition, some polymers do not necessarily require material displacement to absorb shock and vibration that rubber requires.”

Using components made with polymers such as polyurethane can increase the life of the component and suspension as a whole, and can also reduce required maintenance, therefore reducing vehicle downtime.

About the Author

David Brierley | Editor | Fleet Maintenance

David Brierley is a former editor of Fleet Maintenance magazine.

Brierley’s education and career have been based in the publishing industry. He is an award-winning writer and comes from a background in automotive, trucking, and heavy equipment. Brierley joined the Endeavor Business Media vehicle repair group in 2017 as managing editor for Fleet Maintenance, PTEN, and Professional Distributor magazines, as well as In his current role, he writes for and oversees production of Fleet Maintenance magazine. He has worked in the publishing industry since 2011.

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