The buzz of hydraulic wrenches and the clatter of tools fill a cavernous room as workers restore worn-out military Humvees at the former Loring Air Force Base. Even during break time, a few mechanics keep buzzing away.

Hustling to meet self-imposed quotas, the workers know the stakes are high: These Humvees may be headed to Iraq and Afghanistan.

The Maine Military Authority has doubled production to meet demand for Humvees that are being sidelined from the wear and tear of combat operations. Many are equipped to receive heavy armor to protect against roadside bombs.

The importance of the work is never far from workers' thoughts. Some of the most recent arrivals from Kuwait show signs of battlefield damage.

"It's a matter of us doing our jobs so they can do their jobs," said Edward Rek, one of the mechanics giving old Humvees a second life.

The Maine Military Authority got its start overhauling surplus Humvees for National Guard units. It was awarded Army contracts worth $22 million for 620 Humvees this year because Army depots in Pennsylvania and Texas were at capacity.

In Maine, monthly production has grown to 220 units, and the authority expects to deliver 1,900 Humvees by year's end, said general manager Gary Cleaves.

When it was created in 1997, the Maine Military Authority was the only place overhauling castoff Humvees. It started with 14 civilian workers and eight Humvees.

These days, it employs 540 and is one of the biggest success stories of the redevelopment of Loring Air Force Base, which closed in 1994. The outfit is using the former runway maintenance building, the former jet engine maintenance shop and a former supply warehouse.

Across the former base, Humvees are everywhere.

On a recent day, 250 tan-painted Humvees were ready for delivery. Eight hundred additional Humvees were awaiting refurbishing, along with used military vehicles: M-109 howitzers, mobile kitchens and laundry units, maintenance trucks, and construction equipment.

Humvees are also a common sight on local roads. All Humvees undergo 150 miles of road tests before being declared fit for service.

While the Maine Military Authority refurbishes anything with wheels or tracks, it has focused most of its efforts on the military's workhorse Humvee, short for the military name, High-Mobility Multipurpose Wheeled Vehicle.

New Humvees from factories in Indiana and Ohio cost $72,000 to $75,000 apiece. The refurbished ones cost between $25,000 to $40,000, depending on the contract, Cleaves said.

When they arrive, they are in rough shape. Some have smashed glass, torn sheet metal and burn marks from combat. A few were pancaked when parachutes failed to deploy in training. The bulk of them were simply worn out.

Those that cannot be repaired are stripped of useable parts and scrapped. But most of them can be revived by mechanics.

"Give us a frame and some body parts, and we can do the rest," said John Langley, assistant supply and production director. "We can build anything."

All Humvees are getting larger 6.5-liter diesel engines to address soldiers' complaints that they are underpowered. They are also getting updated suspensions and more powerful alternators. And 300 Humvees are being equipped with stronger springs to handle armor plates and thick ballistic glass to better protect soldiers.

They come in different configurations: troop carriers, ambulances, scout vehicles, and missile carriers.

Before they leave, they will be mechanically sound. Body damage will be repaired. And they'll be repainted. Engines are stress-tested on a dynometer for as many as three hours, and transmissions are tested on another machine.

"It has to be right," Langley said. "When someone out there is running through bullets, they have to be reliable."

The Maine Military Authority was created to oversee the Maine Readiness Sustainment Maintenance Center and is managed by the Maine National Guard. Mechanics receive average annual pay of $30,000, and benefits, paychecks and pensions are managed by the state of Maine, Cleaves said.

He sees plenty of additional work down the road. There are 150,000 Humvees assigned to National Guard and regular military units. Those assigned to units returning from Iraq and Afghanistan will need some work, he said. Also, work will continue for National Guard units nationwide, he said.

And Maine Military Authority aims to diversify into nonmilitary work, possibly refurbishing school buses, snowplows and other equipment used by state and local governments.

A mechanic works on a Humvee at the Maine Military Authority managed by the Maine National Guard on the site of the former Loring Air Force Base.

An inside view of a damaged Humvee. Many refurbished vehicles head to Iraq or Afghanistan.