JOLIET, Ill. (CBS) — Peoria-based Caterpillar Inc. has reportedly reached a tentative agreement with machinists at its Joliet plant, who have been on strike for more than three months.

“Caterpillar has signed a tentative six-year contract agreement with leaders of the International Association of Machinists and Aerospace Workers which covers approximately 780 represented employees at the Joliet plant,” company spokesman Rusty Dunn told the Joliet Herald-News.

Dunn said the tentative pact is subject to a ratification vote on Friday by union members. The union has rejected two other offers.

Dunn said he would not make any further comments. A spokesman for the union could not be reached.

The workers went on strike when their contract expired on May 1.

The union members who are part of the International Association of Machinists Lodge 851 say they rejected the contract from Caterpillar because it calls for stagnated wages over the next six years, and higher health care premiums.

The premiums will double for a single person, according to the union.

Under the contract proposal, upper-tier workers would have received no raises at all, while lower-tier workers would have received “market-based” increases to lower-tier workers if warranted.

The company also wants to suspend the defined benefits pension program and the union said it was weakening seniority rights, which Caterpillar denied saying the provisions were the same as in the expired seven-year contract.

Throughout the negotiations, Caterpillar has said it must keep costs down to remain competitive globally. Union members have balked at compensation decreases at a time when the company is making record profits.

Caterpillar has used managers and temporary replacement works to keep production going at the plant, which makes hydraulic components for the company’s mining and earth moving equipment. The Joliet plant on U.S. 6 is the global headquarters for Caterpillar’s hydraulics unit.

The Joliet Herald-News contributed to this report, via the Sun-Times Media Wire.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2012. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

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