I RVINE , CA  A Brink's armored-car guard was crushed to death yesterday when $50,000 in quarters fell on him as the driver braked suddenly to avoid an automobile.

The California Highway Patrol said the Brink's truck was traveling along the San Diego Freeway near Irvine, about 50 miles south of Los Angeles, when driver Scott Daniel Bauman, 29, slammed on his brakes to keep from colliding with a car that had swerved in front of him.

Bauman told the patrol he heard a loud noise in the back of the truck and pulled off on the shoulder of the freeway to investigate. Opening the back door, he said, he found his partner, Hrand Arakelian, 34, buried under a load of 25-pound coin boxes.

Unable to extricate Arakelian without assistance, Bauman said he closed the back door and drove to the nearest exit to summon help. But when he returned he couldn't reopen the door. In his haste, Bauman told authorities, he had locked the back-door key inside the truck. "Anything that could go wrong, went wrong," a police spokesman said. Bauman drove to the nearest exit for help, but upon return couldn't reopen the door. In his haste, he had locked the back-door key inside the truck.

A bystander ran to a nearby store and summoned a locksmith, who was able to open the door about the time paramedics arrived and began removing the coin boxes one by one.