By Bob Tita And Chelsey Dulaney

Activist investor Carl Icahn disclosed a 7.77% stake in Manitowoc Co. on Monday and said he plans to push the company to split itself in two, mirroring an activist campaign launched in June by Relational Investors LLC.

Mr. Icahn wants Manitowoc to separate its construction cranes and commercial food-service equipment segments, his firm said in a regulatory filing. He also indicted that he would seek representation on the company's board. Mr. Icahn and his firm haven't yet engaged in talks with the Wisconsin company.

A Manitowoc representative wasn't immediately available for comment.

Mr. Icahn's breakup plan is likely to attract resistance from Manitowoc Chairman and Chief Executive Glen Tellock. He engineered the purchase of kitchen-equipment manufacturer Enodis PLC for $2.7 billion in 2008. Manitowoc outbid Illinois Tool Works Inc. for the U.K. company, as part of a strategy to offset Manitowoc's cyclical crane operations with a different business. Manitowoc executives have vigorously defended the company's structure, arguing that the crane business is too prone to deep slumps to operate as a stand-alone company.

Mr. Tellock viewed Enodis as a stable, high-margin performer with a roster of customers that included national restaurant chains such as McDonald's, Subway and Pizza Hut. Enodis brands included Delfield refrigerators, Cleveland ranges and Lincoln ovens.

But Manitowoc's kitchen-equipment and crane units both struggled during the 2009 recession. Spending on restaurant expansions and new equipment dried up, while sales of Manitowoc's cranes plunged amid a global slowdown in construction.

Manitowoc's revenue from cranes remains far from its prerecession level, as a recovery in the crane market remains elusive. Crane revenue edged up 3.3% in 2013 to $2.51 billion, but the company expects revenue in 2014 to be down 5% to 9% with about a 7% operating margin.

Sales of food equipment rose 3.7% in 2013 to $1.54 billion. But Manitowoc scaled back expectations for the business this fall as operational problems and higher than expected sales of low-margin models squeezed profit. The company expects revenue from the business to be up 1% to 5% from 2013 with a 15% margin. Investors had expected the margin to be above 16%.

"It was very disappointing year" for food equipment, said Mircea Dobre, an analyst for Robert W. Baird & Co. "Hopeful the performance in 2015 will be a lot better"

In June, Relational Investors LLC disclosed an 8.5% stake in Manitowoc and called for the company to spin off its food-service-equipment business. Relational said Manitowoc's crane and food-service segments are "core, yet incongruent businesses" that "differ materially in their operating metrics and cyclical characteristics."

But Relational's ability to pursue its breakup plan has been hampered by the continuing health challenges of one of its principals, according to analysts. Mr. Icahn has a reputation for persistence and for engaging in board room brawls.

"Mr. Icahn brings resolve," said Mr. Dobre. "He's basically looking at what Relational was trying to do and saying: 'We have the staying power.'"

Mr. Icahn didn't immediately return a phone call for comment. He could launch a proxy fight to gain a majority of the seats on the Manitowoc board. But his ability to expand his Manitowoc stake to leverage changes is limited by a Wisconsin law that discourages an investor from acquiring more than a 10% stake in a company without the permission of the company's board. Mr. Icahn waged two unsuccessful campaigns in 2012 to take over Wisconsin-based specialty truck maker Oshkosh Corp.

Manitowoc started in 1902 as a shipbuilding company in northeast Wisconsin before expanding into the crane business in the 1920s and ice makers and refrigeration equipment after World War II.

Manitowoc was recently up 7.7% at $22.52.

Write to Bob Tita at robert.tita@wsj.com and Chelsey Dulaney at Chelsey.Dulaney@wsj.com

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