ForConstructionPros.com

There are basically four types of drive axle suspension systems for medium- and heavy-duty trucks: rigid mount, steel leaf springs, rubber blocks and air ride. The choice between systems directly impacts the vehicle's ride quality, roll stability, durability, mobility and handling. To maximize productivity and safety, you must understand the trade-offs.

No system works well in every application. "As with almost every truck spec'ing question, the answer is that it depends," says Brian Lindgren, vocational sales director, Kenworth. You must decide which attributes are most important in your application.

On construction sites, one of the most difficult trade-offs is between the feel of the ride and handling. "You are always making a choice between ride quality and roll stability," says Steven Ferro, lead design engineer, medium-duty suspension systems, General Motors.

Suspension designers must pick and choose which conflicting attributes a given suspension system will emphasize. "Roll stability and articulation often work against one another," says Lindgren. "Durability tends to be a trade-off with weight —the heavier ones can be built with more metal so they last longer. Handling, in most cases, comes as a function of roll stability."

Operation in rough, uneven terrain requires different suspension solutions than those running on well-graded jobsites. "If you need a suspension that has extreme articulation because you are going into a site that large earthmovers have just been through, then you might have to trade off more of a lightweight design to get one that has the utmost in articulation," says Matt Stevenson, product marketing manager, Sterling and Western Star Trucks. Cost is also an issue that results in trade-offs.