About 800 union workers who rejected Caterpillar Inc.'s latest contract offer walked off the job Tuesday at a plant in Joliet.

Workers with picket signs lined up outside the plant early Tuesday, just hours after their contract expired. The employees, part of the International Association of Machinists and Aerospace Workers, are asking for better wages and health care. They voted Sunday to reject the Peoria-based company's latest contract offer.

"About 94 percent of the members voted against it," Steve Jones, who is business manager for union's Lodge 851, told The Journal-Star newspaper in Peoria ( http://bit.ly/IperGh).

Production at the plant, which makes hydraulics and other components for mining trucks, tractors and other machines, won't be disrupted, the company said in a statement. The plant has about 1,200 other employees who are not affected by the contract negotiations.

"We are going to continue to run our business as normal, meet production levels and provide uninterrupted service to our customers. Caterpillar has work plans, processes, policies and people ready to be deployed in the event of any business interruption, whether it is a tornado, fire or a labor strike."

Negotiations between the union and Caterpillar have been running for about a month. The company's most recent offer would have held wages at current levels for six years, Jones said, and more than doubled employees' health care costs.

"Essentially, Caterpillar is making record profits, $1.5 billion in the first quarter," Jones said. "But they're taking away from the workers."

A Caterpillar spokesman, Rusty Dunn, called the strike vote unfortunate.