Two Pennsylvania companies are playing critical roles in the race to free 33 Chilean miners who have been trapped 2,300 feet underground in a collapsed copper and gold mine since Aug. 5.

Drilling rigs built by privately held Schramm Inc., of West Chester, have been onsite since rescue efforts began, first reaching the miners Aug. 22 with a 51/2-inch-diameter bore hole used to supply them with food.

Using a drill bit manufactured by a Somerset County firm, Center Rock Inc., a Schramm rig, designed for mineral exploration, expanded one of several pilot holes to 12 inches, reaching the miners Sept. 18.

Now, Schramm and Center Rock are in a group trying to enlarge the 12-inch hole to 28 inches, wide enough to allow the miners to be hoisted to the surface. Two other groups are also drilling.

They had reached a depth of 469 feet late last week, according to Frank C. Gabriel Jr., Schramm's vice president of sales.

Center Rock president Brandon Fisher has been at the site in Chile since Sept. 4, said his wife, Julie Fisher, who is director of sales at the Berlin company, which employs 74.

"His heart and soul is drilling," Fisher said of her husband, 38, who started Center Rock in 1998 and is hands-on at the site to ensure that his drill bit, which combines rotating with hammering, is effective. "In every picture, he's sandy, dusty, and dirty," she said.

On the scene for Schramm is Jeff Roten, a field-service engineer, who is in regular communication with headquarters. Charles Young, a test technician at Schramm West Chester, said he got a call from Roten, a family friend, at 3 a.m. Sept. 16, when Roten was looking for a particular valve on the drilling rig.

With Young's help, Roten was able to find it. "They had relocated it," Young said, referring to the drilling company that owns the rig built by Schramm, which was founded in 1900 in Philadelphia as a manufacturer of air compressors and other machinery driven by engines.

The company moved to West Chester in 1917, according to a borough history on the website of West Chester University, and in the 1950s started manufacturing mobile drilling rigs that are used to drill water wells and natural gas wells and to explore for minerals, such as copper and gold.

Schramm, which employs 157 and is owned by senior management and some employees, has a large share of the market in Chile for rigs mining for mineral deposits.

Schramm rigs are operating in more than 80 countries, with 95 percent of its sales so far this year overseas, in Latin America, Australia, Russia, Africa, and China. Sales peaked in 2008 at 115 rigs, which sell for between $500,000 and $2 million. This year has been better than last year, but sales are only back to 2006 levels, Gabriel said.

When Chile's government summoned drillers to the site in early August, nine came and four of them were using Schramm rigs, Gabriel said, but "in this case, they were exploring to see if they could find the trapped miners."

While Schramm equipment was already on the ground in Chile, Center Rock got there only after the mine collapsed.

Julie Fisher said she and her husband heard on the news Aug. 22 that the miners might not be freed until Christmas. Brandon Fisher thought he could get them out more quickly.

He asked his wife, in jest, if she knew anybody in Chile. Julie Fisher had just been to a meeting of the Southern Alleghenies Planning and Development Commission and learned that Pennsylvania has a trade representative in Chile.

A call to the representative resulted in a conference call Aug. 24 with Chilean officials handling rescue efforts. Center Rock "presented a plan on how we could get them out more quickly," she said.

Eleven days later, Brandon Fisher was on the ground in Chile, his wife said.

Contact staff writer Harold Brubaker at 215-854-4651 or hbrubaker@phillynews.com.