Illinois Caterpillar Plant Faces Strikes From Unions After Expired Contracts

* 800 workers on strike after expired contract

* Caterpillar utilizing replacement workers

* IAM says negotiations are not scheduled

May 1 (Reuters) - About 800 workers went on strike at a Caterpillar Inc plant in Joliet, Illinois, early Tuesday morning after one of the company's union contracts expired with little indication of when a new pact could be in place.

The employees, represented by the International Association of Machinists and Aerospace Workers union, firmly rejected the company's six-year contract offer during a vote Sunday night. On Monday, union officials said talks had ended with Caterpillar.

Caterpillar has responded to the strike by bringing in replacement workers so that it can continue meeting production schedules as planned, spokesman Rusty Dunn said on Tuesday. The workers on strike produce hydraulic components and systems for a variety of Caterpillar machines, including track-type tractors, wheel loaders and mining trucks.

The labor dispute comes as Caterpillar is racing to fill growing demand in North America and in the global mining sector. While the company has experienced a slowdown in China, Europe and Brazil, it is relying on its strength in North America and its mining business to offset that weakness.

IAM's strike also follows a high-profile labor dispute that took place late last year between Caterpillar and the Canadian Auto Workers at a locomotive plant in London, Ontario. CAW workers voted down a Caterpillar offer, and the company ended up closing the plant and moving the work elsewhere.

Steve Jones, an official with the IAM Local 851, said about 50 workers showed up to the picket line in Joliet on Tuesday morning. No further negotiations are scheduled with Caterpillar, he added.

On Monday, Jones told Reuters that Caterpillar's recent offer was rejected because it calls for "wage stagnation" over the next six years and higher health care premiums.

"We're going to be in a much worse economic position six years from now than we are now," Jones said. Caterpillar has said the company its proposed deal represented a "competitive contract offer."

Shares of Caterpillar were unchanged at $102.77 in trading before the market opened.