A trucking company owner has pleaded not guilty to killing one of his drivers and endangering the lives of two others by failing to maintain the vehicle's brakes.

55-year-old Peter Francis Colbert of Athol Park in Adelaide has faced the Supreme Court, charged over the manslaughter of 45-year-old Robert Brimson.

The Salisbury father of two was killed nine months ago when the truck he was driving crashed into a road sign at Happy Valley.

Colbert also pleaded not guilty to endangering the lives of two other drivers on the same day, after they'd earlier driven the truck involved in the fatal crash.

- AAP