Bouncing Back: The striker, four inches in diameter, packs punches that test the seats' ability to absorb energy and impact. | Photos: Roark Johnson
At Navistar’s vehicle testing facility in Melrose Park, Ill., IC Bus products are subjected to a barrage of tests for everything from strength and durability to mirror visibility. Engineers check all components in accordance with the Federal Motor Vehicle Safety Standards and Regulations.
“The responsibility we have to keep students and passengers safe is always at the front of our mind,” says Tom Grotto, Melrose Park’s chief engineer of applied mechanics and body validation. Here, Grotto gives us a firsthand look at three of the toughest tests his team throws at each and every new design that rolls off the IC Bus line.
Knee and Head Impact
To protect passengers in an accident, federal safety standards mandate seat impact requirements. Grotto and his engineers verify compliance with these requirements utilizing distinct strikers built to the standard’s specifications to simulate a knee or head, as well as accelerometers to measure energy. “The rear of the seat has to absorb energy and impact,” Grotto says. “So we check every spot.”
This test examines rollover safety. A large plate, built to specifications provided by the safety standards, is pressed into a bus’ roof until the required force is achieved. The downward movement of the plate is measured and compared with the limit established by the standard, and all emergency exits are checked to verify compliant operation.
Engineers chain buses to the floor and assault them with an enormous battering ram to test the front end’s reaction to a head-on collision. An equation is used to ensure that the 4,500-pound striker’s force and angle of release are correct. And then: wham. “It’s basically a pendulum that we raise almost until it’s touching the ceiling,” Grotto says. “Then we release it, and it strikes the front of the vehicle.”