More than 22,000 heavy trucks are being ordered off the highways because of potential defects in their power steering gears that could result in "sudden and catastrophic failure," the National Highway Traffic Safety Administration said Friday.

The TRW Ross Gear division, which produced the steering gears, and manufacturers of Peterbilt, Kenworth, Freightliner, Western Star and White GMC trucks, urged that affected trucks be removed from highways immediately and towed to the nearest truck dealer, the agency said.The recall affects 22,687 trucks carrying certain steering gears manufactured by TRW Ross Gear division since last March. The safety agency said TRW has confirmed seven incidents of steering gear failure since June.