US road safety regulators have launched an investigation into about half a million semi-trailers whose brakes can catch fire.
The National Highway Traffic Safety Administration said in documents posted on its website Tuesday that it had 11 brake complaints filed by Haldex Commercial Vehicle Systems, including seven fires. No injuries were reported.
The complaints indicate that the problems mainly arose in the Kenworth and Peterbilt semi-finals. The agency is studying the brakes for the 2015 to 2020 model years.
NHTSA says the investigation is focused on certain Haldex Gold Seal brake receivers, which convert compressed air into mechanical force that stops trucks. He says a spring can snap, puncture a diaphragm and cause air loss. This can cause the brakes to slip without warning the driver and possibly cause fires.
The fires caused extensive damage to trucks and, in some cases, cargo, the agency said. NHTSA says it has learned that several truck fleets have problems with brake receivers. He says Haldex has replaced the brake receivers on some fleet vehicles.
NHTSA says it will determine how often the problem occurs and what patterns it affects. An investigation can lead to a recall.
Messages were left on Tuesday seeking comment from Haldex, which is headquartered in the United States in Kansas City, Missouri.