The Testing Behind The New International® Terrastar™

With the upcoming 16,000-19,500 GVWR International® TerraStar™ currently in testing, Ken Clark, senior reliability engineer at Navistar, takes us into the lab to share the steps taken to ensure that the new truck, like all International products, will deliver best-in-class quality, durability, and reliability.

According to Clark, part of his role is to determine the level of testing required prior to new product launches. One of his first tasks involves considering what components are common to existing International® trucks. For example, in the case of the International TerraStar, many of the components are the same as those used to build the popular International DuraStar® vehicle. "It’s not a ‘clean-sheet-of-paper’ design," he explains. "How much testing we need to do depends on how much carryover confidence we have. And the DuraStar is already a proven truck."
However, because the TerraStar features a new hood design (a tilt-away hood that offers unobstructed access to the engine compartment) that differs from the DuraStar, engineers must conduct shaker tests; during these tests, a computer-controlled hydraulic machine bumps and jostles the cab and hood to stimulate the activity of a vehicle traveling actual roads.

"The purpose is to make sure the hood is adequately durable," says Clark. "The hood does more than just cover the engine. It’s an assembly that holds the headlights and the grille. It’s designed to be both functional and attractive, and we need to make sure it’s going to last."
All International trucks also go through full durability tests, where pilot vehicles are run across simulated rough terrain on a closed track to accelerate structural damage. Over three months, lab technicians can put the equivalent of 10 years of fatigue onto the chassis and body.

"We have measured customer fleets and built wear-and-tear simulations around types of roads, and the types of things certain vehicles will likely see," says Clark. "We run trucks over two sets of rectangular steel bars on our test track to simulate railroad crossings. And we’ll customize the tests based on vehicle and vocation. For example, a WorkStar® tends to run in a more severe environment, such as construction, so it may see 10 times the railroad crossings that a ProStar® will see. The durability test will be built around these expectations."

The track also features shallow trenches that represent bridge expansion joints and areas with different curb heights and depths. "The idea is, the left front tire goes down while the right front tire goes up; and on the rear axle, it’s the opposite," Clark continues. "You’re trying to put a twisting load into the frame and suspension to provide the equivalent of a delivery truck running over a curb, or a dump truck driving out of a quarry."

There are other durability events that represent different types of rough surfaces over which a truck may be driven. The durability test will utilize those events that are suitable for the expected vocation of the vehicle.

All results are recorded in a database, and any issues that are discovered are immediately communicated back to truck designers, who incorporate the findings into redesigns.

Even though the International TerraStar is already in production, Navistar engineers are constantly testing the vehicle to ensure maximum quality. For example, the TerraStar is currently going through uptime testing, which measures reliability by placing four pilot vehicles on the road for 36,000 miles each. Whereas durability tests gauge how long a truck is going to last, uptime tests determine whether the truck performs the way it is supposed to perform.

"With the TerraStar, we’re driving the trucks in urban and suburban environments, running part of the time loaded and other times unloaded, looking for anything the customer might experience," says Clark, who notes that much of the test routes are based on the TerraStar’s expected usage, such as intra-city pick-up and delivery applications.

"The truck is testing extremely well," he says. "I think it’s unique in that it’s a Class 4/5 that’s going to offer the advantages of a Class 6 truck in a lighter package. Anyone who could use the durability and reliability of a real truck for their business is going to find the TerraStar a compelling option."

The TerraStar truck will initially be available with a 4x2 drivetrain this fall with a 4x4 drivetrain planned for release in 2011.

For more information, go to: www.internationaltrucks.com/terrastarbuildyourown

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